Glossary
An XML document that specifies the set of attributes to be made anonymous, and defines the actions required to make those attributes anonymous.
The semantic consistency of DICOM content with regard to application-specific constraint rules, which can be stronger or weaker than rules in the DICOM standard. Administrators can define constraint documents to include user-defined rules that are specific to a particular organization.
A unique document for each database instance that is applicable to all DICOM content stored in the database. Configuration documents are managed by the repository. Examples include private and standard dictionary documents, mapping documents, constraint documents, and preference documents.
The process of checking the conformance of DICOM content against a set of constraint documents that define rules with which to validate conformance. Oracle extends conformance validation to DICOM metadata documents as well.
An XML document that defines a collection of rules to validate the conformance of DICOM content, according to the DICOM standard and other organization-wide guidelines. Constraint documents specify the relationships and semantic constraints of attributes that are not expressed by the DICOM metadata schema. Constraint documents are based on the SOP class specification defined in Part 3 of the DICOM standard. Administrators can define constraint documents to include user-defined rules that are specific to a particular organization.
A simplified definition of a complex constraint rule. Constraint macros can be defined as global macros, and follow the same predicate definition grammar as constraint rules. Constraint macros can include predicate operands, which can contain macro parameters that are replaced with parameter values when the macro is invoked. Constraint macros can also be recursive, which is useful when specifying validation requirements for hierarchical or recursive structured DICOM content.
A definition of a condition that operates on individual attributes or sets of attributes in the DICOM content. A constraint predicate can be a logical statement, a relational statement that compares values, a function call evaluation that returns a Boolean type, or a reference to other predicate definitions. Predicate definitions are recursive.
A collection of rules to validate the conformance of DICOM content according to the DICOM standard. These rules are defined in constraint documents, which specify the relationships and semantic rules of attributes that are not expressed by the DICOM metadata schema. Administrators can define constraint documents to include user-defined rules that are specific to a particular organization.
A set of collectively managed, user-configurable documents that defines the run-time behavior of Oracle Multimedia DICOM. Administrators can update the repository to configure Oracle Multimedia DICOM for a particular database instance.
An encoded representation of the metadata within DICOM content that can be used with XML schemas. DICOM attribute tags include standard tags, which are supported by the DICOM standard, and user-defined private tags. DICOM attribute tags contain a group number and an element number.
A utility that checks the syntactical and semantic consistency of DICOM content in accordance with constraint rules specified in the data model repository.
Multiple standalone DICOM Information Objects that are structured and encoded as defined in Part 10 of the DICOM standard (commonly referred to as DICOM Part 10 files). For more information, see the DICOM standard on the NEMA Web site at
● DICOM data type definition schema
An XML schema that defines the value representations (DICOM data types) provided in Part 5 of the DICOM standard. This data type definition schema is strongly coupled with the DICOM parser. It is designed by Oracle, the content is fixed, and it ships with Oracle Multimedia.
Any DICOM content that can be decomposed into 2-D pixel arrays. Examples include a video segment, a volume scan, and a single-frame dental image.
An XML document that contains the metadata, as encoded attributes, extracted from DICOM content. Oracle provides methods to build a metadata document from DICOM content. Each metadata schema requires a mapping document that defines how attributes from the DICOM content are to be mapped into an XML document that conforms to the schema. In addition, each metadata schema references the DICOM data type definition schema.
A standalone DICOM Information Object, which is constructed in accordance with the data structure and encoding definitions specified in Part 10 of the DICOM standard. For more information, see the DICOM standard on the NEMA Web site at
The dominant standard for radiology imaging and communication to which all major manufacturers conform. The DICOM standard is primarily developed and maintained by working groups of domain experts. A new version is usually published once a year. The standard is available worldwide from the National Electrical Manufacturers Association (NEMA) Web site at
A DICOM type that identifies an attribute in the DICOM content, either at the root level or from the root level down. Each level in the tree hierarchy is represented by a sublocator.
A set of images gathered in a single imaging operation. These images can be stored as separate slices in multiple ORDDicom objects. Or, they can be stored as single ORDDicom multiframe objects.
A utility that converts the in-memory structure of the extracted DICOM attributes into an XML document.
● Digital Imaging and Communications in Medicine (DICOM)
A medical imaging standard initiated by the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) to enhance the connectivity of radiological devices.
A utility that includes Java Advanced Imaging (JAI). This utility provides support for operations such as producing thumbnail-size images and converting between DICOM and other supported image formats. When used with Oracle Multimedia DICOM methods, this utility supports import and export operations between the database and operating system files (external file storage).
An object-oriented representation of a real world entity in DICOM. Examples include images and waveforms captured by imaging devices.
An XML file that is created when exporting a set of configuration documents from a DICOM repository, and used when importing a set of configuration documents into a DICOM repository. For each configuration document within the set to be imported, the manifest document specifies the name of the configuration document, the document type, and the load order. The default manifest document is ordcmmft.xml. This document conforms to the registered XML schema ordcmmft.xsd.
A part of a DICOM data element whose XML path is explicitly defined in a mapping document.
A part of a DICOM data element whose XML path is not explicitly defined in a mapping document.
An XML document that defines how each attribute maps to a particular element of a DICOM XML metadata document. This document determines the structure of the extracted XML representation of the DICOM metadata.
The process of encoding the extracted DICOM attributes into a DICOM metadata document.
The XML schema document that constrains the DICOM metadata document. This schema references the DICOM data type definition schema. Oracle supports customization of the metadata schema for each instance of the database. Oracle ships a default metadata schema with Oracle Multimedia. Administrators can update the default metadata schema and the corresponding mapping document to define a schema that is specific to the database instance.
A property of DICOM value locators that exists when the last attribute tag in an array is specified as DICOM type SQ, OW, OB, OF, or UN.
In Oracle Database 11g Release 1 (11.1), the name Oracle interMedia was changed to Oracle Multimedia.
A database object used to encapsulate DICOM content and extracted attributes. The database object has public member methods that permit the querying and processing of ORDDicom objects.
An XML document that defines a set of run-time parameters, such as specifying whether Oracle Multimedia DICOM skips invalid attributes and their values in the binary output of DICOM content when making a copy of DICOM content. Oracle ships a default preference document with Oracle Multimedia. Administrators can update the default preference document to change the run-time behavior. For example, administrators can specify whether to validate XML documents used in DICOM functions and procedures or cause attributes larger than a specified size to be omitted when encoding attributes into XML.
A set of attributes defined by an organization and encoded in DICOM content according to the encoding rules set by that organization for those attributes. Private attributes can add modality-specific, manufacturer-specific, or site-specific information to DICOM content. Private attributes are not administered by the DICOM standard, and they are generally not known or used by any organization other than the one that defined the private attributes.
A document that lists the private attributes in the data dictionary. A data dictionary can contain one or more private dictionary documents. Each private dictionary document contains the definitions for a set of private attributes and the UID of the organization that defined the private attributes. Private dictionary documents can be published by Oracle or a third party. DICOM administrators can add new private dictionary documents to the data dictionary as they become available. Private dictionary documents enable users to extend the standard dictionary document definitions by adding manufacturer-specific or enterprise-specific attributes to DICOM content. Private dictionary documents are constrained by private dictionary schemas.
A library used to store documents that are applicable to all ORDDicom objects stored in a database instance. Administrators can access the repository and update the documents stored in it. Changes made to these documents change the outcome of the affected Oracle Multimedia DICOM methods and procedures. Examples of documents stored in the repository include mapping documents, data dictionary documents, and constraint documents. At run time, a specified method is used to query the repository to obtain the latest copy of these documents. For example, a DICOM administrator can update an attribute definition in a data dictionary document and change its data type from DA (date) to DT (date time). From that point forward, after setting to the new data model the parser interprets the attribute as an instance of the DT data type, and the metadata encoder encodes the attribute as DT in all future metadata documents.
A property of DICOM value locators in an array of attribute tags for supported DICOM types.
The process of using an XML schema definition to validate an XML document that is constrained by the schema. Schema validation enables users to confirm the correctness of data types, data formats, and data hierarchies. Schema validation applies to XML documents only. It does not apply to DICOM content.
A service object pair (SOP) class. This class is used to model a category of information object and a set of operations associated with that information object.
The set of attributes defined by the DICOM Standards Committee, which is published in Part 6 of the DICOM standard. Standard attributes can be modified or deprecated by the DICOM Standards Committee in the future. The number of standard attributes increases each year as the DICOM standard expands to include new areas of technology.
● standard dictionary document
A document that lists the attributes defined by the DICOM standard. The DICOM standard dictionary document is converted from Part 6 of the DICOM standard. The DICOM Standards Committee expects to publish this document in XML format in the future. Oracle software releases include a copy of the standard dictionary document tied to a particular release of the DICOM standard. Administrators can update this standard dictionary document to reflect the most recent changes made by the DICOM Standards Committee.
The syntactical and semantic consistency of DICOM content with regard to the DICOM standard. The default constraint document that Oracle ships with Oracle Multimedia defines rules that enforce conformance with parts of the DICOM standard.
An optional XML document that specifies the DICOM attributes to be extracted from the embedded DICOM content and stored in the XML metadata attribute of the ORDDicom object when the setProperties( ) method is called. Generally, stored tag list documents contain the attribute tags used in mapping and constraint documents.
Encoding rules for medical imaging that specify how to encode DICOM content into a binary stream. These rules also specify how to compress the data content. Supported DICOM compression schemes (codecs) include RLE, JPEG, and JPEG2000.
An XML document that lists unique identifiers (UIDs) defined by the DICOM standard or a private organization. Rather than defining the DICOM content UIDs, UID definition documents contain a registry of standard UIDs that classify the DICOM content and express standard semantics.
A 64-byte, dot-concatenated, numeric string (similar to an IP address). The UID is based on an ISO object identifier (OID). It is commonly constructed with a root that uniquely identifies the organization producing the DICOM content, and a suffix that uniquely identifies the DICOM content within that organization.
A constraint rule that specifies how many times the value of an attribute can be repeated. It is part of the standard attribute specification (defined in Part 6 of the DICOM standard).
The data type, as defined by the DICOM standard. The DICOM standard defines standard data types in Part 5. See the XML schema ordcmrdt.xsd (available in the ord/dicom/xml/xsd directory under <ORACLE_HOME>) for more information about the data types supported by Oracle Multimedia DICOM.
An XML document used to define how to map DICOM attributes to elements in the DICOM metadata document. The XML mapping document is used by the metadata encoder to produce a DICOM metadata document. Because the metadata document is constrained by the metadata schema, the XML mapping document must match the metadata schema. Oracle Multimedia defines a default mapping document that coincides with the DICOM metadata schema. Administrators can update the mapping document and the corresponding metadata schema to define a schema that is specific to each database instance.
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GlossaryGlossary
A mark that changes the sound of a character. Because the common meaning of accent is associated with the stress or prominence of the character's sound, the preferred word in Oracle Database Globalization Support Guide is diacritic.
See also diacritic.
● accent-insensitive linguistic sort
A linguistic sort that uses information only about base letters, not diacritics or case.
See also linguistic sort, base letter, diacritic, case.
The default Oracle Database character set for the SQL NCHAR data type, which is used for the national character set. It encodes Unicode data in the UTF-16 encoding.
See also national character set.
An Oracle Database character set for the SQL CHAR data type, which is used for the database character set. It encodes Unicode data in the UTF-8 encoding.
See also database character set.
American Standard Code for Information Interchange. A common encoded 7-bit character set for English. ASCII includes the letters A-Z and a-z, as well as digits, punctuation symbols, and control characters. The Oracle Database character set name is US7ASCII.
A character without diacritics. For example, the base letter for a, A, ?, and ? is a.
See also diacritic.
Treatment of strings as a sequence of bytes.
See also character semantics and length semantics.
A basic equivalence between characters or sequences of characters. For example, ? is equivalent to the combination of c and ,. They cannot be distinguished when they are correctly rendered.
Refers to the condition of being uppercase or lowercase. For example, in a Latin alphabet, A is the uppercase glyph for a, the lowercase glyph.
● case-insensitive linguistic sort
A linguistic sort that uses information about base letters and diacritics but not case.
See also base letter, case, diacritic, linguistic sort.
A character is an abstract element of text. A character is different from a glyph, which is a specific representation of a character. For example, the first character of the English upper-case alphabet can be displayed as A, A, A, and so on. These forms are different glyphs that represent the same character. A character, a character code, and a glyph are related as follows:
character --(encoding)--> character code --(font)--> glyph
For example, the first character of the English uppercase alphabet is represented in computer memory as a number. The number is called the encoding or the character code. The character code for the first character of the English uppercase alphabet is 0x41 in the ASCII encoding scheme. The character code is 0xc1 in the EBCDIC encoding scheme.
You must choose a font to display or print the character. The available fonts depend on which encoding scheme is being used. The character can be printed or displayed as A, A, or A, for example. The forms are different glyphs that represent the same character.
See also character code and glyph.
Information provides details about the type of character associated with each character code. For example, a character can be uppercase, lowercase, punctuation, or control character.
A character code is a number that represents a specific character. The number depends on the encoding scheme. For example, the character code of the first character of the English uppercase alphabet is 0x41 in the ASCII encoding scheme, but it is 0xc1 in the EBCDIC encoding scheme.
See also character.
A rule that assigns numbers (character codes) to all characters in a character set. Encoding scheme, encoding method, and encoding also mean character encoding scheme.
The characters that are available to be used, or encoded, for a specific character set.
Treatment of strings as a sequence of characters.
See also byte semantics and length semantics.
A collection of elements that represent textual information for a specific language or group of languages. One language can be represented by more than one character set.
A character set does not always imply a specific character encoding scheme. A character encoding scheme is the assignment of a character code to each character in a character set.
In this manual, a character set usually does imply a specific character encoding scheme. Therefore, a character set is the same as an encoded character set in this manual.
An ordered group of characters.
A character string can also contain no characters. In this case, the character string is called a null string. The number of characters in a null string is 0 (zero).
The encoded character set used by the client. A client character set can differ from the server character set. The server character set is called the database character set. If the client character set is different from the database character set, then character set conversion must occur.
See also database character set.
The numeric representation of a character in a character set. For example, the code point of A in the ASCII character set is 0x41. The code point of a character is also called the encoded value of a character.
See also Unicode code point.
The unit of encoded text for processing and interchange. The size of the code unit varies depending on the character encoding scheme. In most character encodings, a code unit is 1 byte. Important exceptions are UTF-16 and UCS-2, which use 2-byte code units, and wide character, which uses 4 bytes.
See also character encoding scheme.
Ordering of character strings according to rules about sorting characters that are associated with a language in a specific locale. Also called linguistic sort.
See also linguistic sort, monolingual linguistic sort, multilingual linguistic sort, accent-insensitive linguistic sort, case-insensitive linguistic sort.
The process of identifying potential problems with character set conversion and truncation of data before migrating the database character set.
The encoded character set that is used to store text in the database. This includes CHAR, VARCHAR2, LONG, and fixed-width CLOB column values and all SQL and PL/SQL text.
A mark near or through a character or combination of characters that indicates a different sound than the sound of the character without the diacritical mark. For example, the cedilla in fa?ade is a diacritic. It changes the sound of c.
Extended Binary Coded Decimal Interchange Code. EBCDIC is a family of encoded character sets used mostly on IBM systems.
A character set with an associated character encoding scheme. An encoded character set specifies the number (character code) that is assigned to each character.
See also character encoding scheme.
The numeric representation of a character in a character set. For example, the code point of A in the ASCII character set is 0x41. The encoded value of a character is also called the code point of a character.
An ordered collection of character glyphs that provides a graphical representation of characters in a character set.
The process of making software suitable for different linguistic and cultural environments. Globalization should not be confused with localization, which is the process of preparing software for use in one specific locale (for example, translating error messages or user interface text from one language to another).
A glyph (font glyph) is a specific representation of a character. A character can have many different glyphs. For example, the first character of the English uppercase alphabet can be printed or displayed as A, A, A, and so on. These forms are different glyphs that represent the same character.
See also character.
A symbol that represents an idea. Chinese is an example of an ideographic writing system.
International Organization for Standards. A worldwide federation of national standards bodies from 130 countries. The mission of ISO is to develop and promote standards in the world to facilitate the international exchange of goods and services.
A family of 8-bit encoded character sets. The most common one is ISO 8859-1 (also known as ISO Latin1), and is used for Western European languages.
A multilingual linguistic sort standard that is designed for almost all languages of the world.
See also multilingual linguistic sort.
A universal character set standard that defines the characters of most major scripts used in the modern world. In 1993, ISO adopted Unicode version 1.1 as ISO/IEC 10646-1:1993. ISO/IEC 10646 has two formats: UCS-2 is a 2-byte fixed-width format, and UCS-4 is a 4-byte fixed-width format. There are three levels of implementation, all relating to support for composite characters:
-
Level 1 requires no composite character support.
-
Level 2 requires support for specific scripts (including most of the Unicode scripts such as Arabic and Thai).
-
Level 3 requires unrestricted support for composite characters in all languages.
The 3-letter abbreviation used to denote a local currency, based on the ISO 4217 standard. For example, USD represents the United States dollar.
The ISO 8859-1 character set standard. It is an 8-bit extension to ASCII that adds 128 characters that include the most common Latin characters used in Western Europe. The Oracle Database character set name is WE8ISO8859P1.
See also ISO 8859.
Length semantics determines how you treat the length of a character string. The length can be treated as a sequence of characters or bytes.
See also character semantics and byte semantics.
An ordering of strings based on requirements from a locale instead of the binary representation of the strings.
See also multilingual linguistic sort and monolingual linguistic sort.
A collection of information about the linguistic and cultural preferences from a particular region. Typically, a locale consists of language, territory, character set, linguistic, and calendar information defined in NLS data files.
The process of providing language-specific or culture-specific information for software systems. Translation of an application's user interface is an example of localization. Localization should not be confused with globalization, which is the making software suitable for different linguistic and cultural environments.
An Oracle Database sort that has two levels of comparison for strings. Most European languages can be sorted with a monolingual sort, but it is inadequate for Asian languages.
See also multilingual linguistic sort.
Two or more bytes.
When character codes are assigned to all characters in a specific language or a group of languages, one byte (8 bits) can represent 256 different characters. Two bytes (16 bits) can represent up to 65,536 different characters. Two bytes are not enough to represent all the characters for many languages. Some characters require 3 or 4 bytes.
One example is the UTF8 Unicode encoding. In UTF8, there are many 2-byte and 3-byte characters.
Another example is Traditional Chinese, used in Taiwan. It has more than 80,000 characters. Some character encoding schemes that are used in Taiwan use 4 bytes to encode characters.
See also single byte.
A character whose character code consists of two or more bytes under a certain character encoding scheme.
Note that the same character may have different character codes under different encoding schemes. Oracle Database cannot tell whether a character is a multibyte character without knowing which character encoding scheme is being used. For example, Japanese Hankaku-Katakana (half-width Katakana) characters are one byte in the JA16SJIS encoded character set, two bytes in JA16EUC, and three bytes in UTF8.
See also single-byte character.
A character string that consists of one of the following strings:
-
No characters (called a null string)
-
One or more single-byte characters
-
A mixture of one or more single-byte characters and one or more multibyte characters
-
One or more multibyte characters
● multilingual linguistic sort
An Oracle Database sort that evaluates strings on three levels. Asian languages require a multilingual linguistic sort even if data exists in only one language. Multilingual linguistic sorts are also used when data exists in several languages.
An alternate character set from the database character set that can be specified for NCHAR, NVARCHAR2, and NCLOB columns. National character sets are in Unicode only.
Binary files used by the Locale Builder to define locale-specific data. They define all of the locale definitions that are shipped with a specific release of Oracle Database. You can create user-defined NLB files with Oracle Locale Builder.
See also Oracle Locale Builder and NLT files.
National Language Support. NLS enables users to interact with the database in their native languages. It also enables applications to run in different linguistic and cultural environments. The term is somewhat obsolete because Oracle Database supports multiple global users at one time.
National Language Support Runtime Library. This library is responsible for providing locale-independent algorithms for internationalization. The locale-specific information (that is, NLSDATA) is read by the NLSRTL library during run-time.
Text files used by the Locale Builder to define locale-specific data. Because they are in text, you can view the contents.
A GUI utility that offers a way to view, modify, or define locale-specific data. You can also create your own formats for language, territory, character set, and linguistic sort.
A character used during character conversion when the source character is not available in the target character set. For example, ? (question mark) is often used as the default replacement character for Oracle Database.
● restricted multilingual support
Multilingual support that is restricted to a group of related languages.Western European languages can be represented with ISO 8859-1, for example. If multilingual support is restricted, then Thai could not be added to the group.
A particular system of writing. A collection of related graphic symbols that are used in a writing system. Some scripts can represent multiple languages, and some languages use multiple scripts. Examples of scripts include Latin, Arabic, and Han.
One byte. One byte usually consists of 8 bits. When character codes are assigned to all characters for a specific language, one byte (8 bits) can represent 256 different characters.
See also multibyte.
A single-byte character is a character whose character code consists of one byte under a specific character encoding scheme. Note that the same character may have different character codes under different encoding schemes. Oracle Database cannot tell which character is a single-byte character without knowing which encoding scheme is being used. For example, the euro currency symbol is one byte in the WE8MSWIN1252 encoded character set, two bytes in AL16UTF16, and three bytes in UTF8.
See also multibyte character.
● single-byte character string
A single-byte character string consists of one of the following strings:
-
No character (called a null string)
-
One or more single-byte characters
The first version of Unicode was a 16-bit, fixed-width encoding that used two bytes to encode each character. This enabled 65,536 characters to be represented. However, more characters need to be supported because of the large number of Asian ideograms.
Unicode 3.1 defined supplementary characters to meet this need. Unicode 3.1 began using two 16-bit code units (also known as surrogate pairs) to represent a single character. This enabled an additional 1,048,576 characters to be defined. The Unicode 3.1 standard added the first group of 44,944 supplementary characters. More were added with Unicode 4.0 versions, and 1,369 more have been added with Unicode 5.0.
See also supplementary characters.
Provide a mechanism for communicating phonetic information along with the ideographic characters used by languages such as Japanese.
A 1993 ISO/IEC standard character set. It is a fixed-width, 16-bit Unicode character set. Each character occupies 16 bits of storage. The ISO Latin1 characters are the first 256 code points, so it can be viewed as a 16-bit extension of ISO Latin1.
A fixed-width, 32-bit Unicode character set. Each character occupies 32 bits of storage. The UCS-2 characters are the first 65,536 code points in this standard, so it can be viewed as a 32-bit extension of UCS-2. This is also sometimes referred to as ISO-10646.
Unicode is a universal encoded character set that enables information from any language to be stored by using a single character set. Unicode provides a unique code value for every character, regardless of the platform, program, or language.
A value in the Unicode codespace, which ranges from 0 to 0x10FFFF. Unicode assigns a unique code point to every character.
A SQL NCHAR data type (NCHAR, NVARCHAR2, and NCLOB). You can store Unicode characters in columns of these data types even if the database character set is not Unicode.
● unrestricted multilingual support
The ability to use as many languages as desired. A universal character set, such as Unicode, helps to provide unrestricted multilingual support because it supports a very large character repertoire, encompassing most modern languages of the world.
A Unicode 5.0 UTF-8 Oracle Database character set with 6-byte supplementary character support. It is used only on EBCDIC platforms.
The UTF8 Oracle Database character set encodes characters in one, two, or three bytes. It is for ASCII-based platforms. The UTF8 character set supports Unicode 5.0 and it is compliant to the CESU-8 standard. Although specific supplementary characters were not assigned code points in Unicode until version 3.1, the code point range was allocated for supplementary characters in Unicode 3.0. Supplementary characters are treated as two separate, user-defined characters that occupy 6 bytes.
The 8-bit encoding of Unicode. It is a variable-width encoding. One Unicode character can be 1 byte, 2 bytes, 3 bytes, or 4 bytes in UTF-8 encoding. Characters from the European scripts are represented in either 1 or 2 bytes. Characters from most Asian scripts are represented in 3 bytes. Supplementary characters are represented in 4 bytes. The Oracle Database character set that supports UTF-8 is AL32UTF8.
The 16-bit encoding of Unicode. It is an extension of UCS-2 and supports the supplementary characters defined in Unicode by using a pair of UCS-2 code points. One Unicode character can be 2 bytes or 4 bytes in UTF-16 encoding. Characters (including ASCII characters) from European scripts and most Asian scripts are represented in 2 bytes. Supplementary characters are represented in 4 bytes. The Oracle Database character set that supports UTF-16 is AL16UTF16.
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GlossaryGlossary
In the external table infrastructure, the API that interprets the external data for the database. The access driver runs inside the database, which uses the driver to read the data in the external table.
The means by which data is retrieved from a database. For example, a query using an index and a query using a full table scan use different access paths.
Automatic Database Diagnostic Monitor. An Oracle Database infrastructure that enables a database to diagnose its own performance and determine how identified problems could be resolved.
Automatic Diagnostic Repository. A a file-based hierarchical data store for managing diagnostic information, including network tracing and logging.
A file that provides a chronological log of database messages and errors. The alert log is stored in the ADR.
A join that returns rows from the left side of the predicate for which there are no corresponding rows on the right side of the predicate.
The computing environment in which a database application connects to an Oracle database. The two most common database architectures are client/server and multitier.
A member of the online redo log that has been archived by Oracle Database. The archived redo log files can be applied to a database backup in media recovery.
A mode of the database that enables the archiving of the online redo log.
An index in which data is stored in ascending order. By default, character data is ordered by the binary values contained in each byte of the value, numeric data from smallest to largest number, and date from earliest to latest value.
● Automatic Database Diagnostic Monitor (ADDM)
See ADDM.
● Automatic Diagnostic Repository (ADR)
See ADR.
● automatic undo management mode
A mode of the database in which it automatically manages undo space in a dedicated undo tablespace.
See also manual undo management mode.
● Automatic Workload Repository (AWR)
See AWR.
Automatic Workload Repository (AWR). A built-in repository in every Oracle database. Oracle Database periodically makes a snapshot of its vital statistics and workload information and stores them in AWR.
An index organized like an upside-down tree. A B-tree index has two types of blocks: branch blocks for searching and leaf blocks that store values. The leaf blocks contain every indexed data value and a corresponding rowid used to locate the actual row. The "B" stands for "balanced" because all leaf blocks automatically stay at the same depth.
A process that consolidates functions that would otherwise be handled by multiple Oracle programs running for each client process. The background processes asynchronously perform I/O and monitor other Oracle processes.
See also instance; Oracle process.
A placeholder in a SQL statement that must be replaced with a valid value or value address for the statement to execute successfully. By using bind variables, you can write a SQL statement that accepts inputs or parameters at run time. The following example shows a query that uses v_empid as a bind variable:
SELECT * FROM employees WHERE employee_id = :v_empid;
A database index in which the database stores a bitmap for each index key instead of a list of rowids.
An operation that merges bitmaps retrieved from bitmap index scans. For example, if the gender and DOB columns have bitmap indexes, then the database may use a bitmap merge if the query predicate is WHERE gender='F' AND DOB > 1966.
A data block that is not in a recognized Oracle format, or whose contents are not internally consistent.
A part of a data block that includes information about the type of block, the address of the block, and sometimes transaction information.
Space in a data block that stores metadata required for managing the block. The overhead includes the block header, table directory, and row directory.
In a B-tree index, a block that the database uses for searching. The leaf blocks store the index entries. The upper-level branch blocks of a B-tree index contain index data that points to lower-level index blocks.
A main memory address in the database buffer cache. A buffer caches currently and recently used data blocks read from disk. When a new block is needed, the database can replace an old data block with a new one.
Treatment of strings as a sequence of bytes. Offsets into strings and string lengths are expressed in bytes.
The phase of instance recovery where Oracle Database applies all committed and uncommitted changes in the online redo log files to the affected data blocks.
The ratio of distinct values to the number of table rows. A column with only two distinct values in a million-row table would have low cardinality.
A code that pairs each character from a given repertoire with a code unit to facilitate data storage.
Treatment of strings as a sequence of characters. Offsets into strings and string lengths are expressed in characters (character codes).
1. A data structure that marks the checkpoint position, which is the SCN in the redo thread where database instance recovery must begin. Checkpoints are recorded in the control file and each data file header, and are a crucial element of recovery.
2. The writing of dirty data blocks in the database buffer cache to disk. The database writer (DBW) process writes blocks to disk to synchronize the buffer cache with the data files.
In client/server architecture, the front-end database application that interacts with a user. The client portion has no data access responsibilities.
A process that executes the application or Oracle tool code. When users run client applications such as SQL*Plus, the operating system creates client processes to run the applications.
See also Oracle process.
Software architecture based on a separation of processing between two CPUs, one acting as the client in the transaction, requesting and receiving services, and the other as the server that provides services in a transaction.
A distributed file system that is a cluster of servers that collaborate to provide high performance service to their clients.
In a table cluster, the column or columns that the clustered tables have in common. For example, the employees and departments tables share the department_id column. You specify the cluster key when creating the table cluster and when creating every table added to the table cluster.
Vertical space in a table that represents a domain of data. A table definition includes a table name and set of columns. Each column has a name and data type.
Action that ends a database transaction and makes permanent all changes performed in the transaction.
In partitioning strategy in which a table is partitioned by one data distribution method and then each partition is further divided into subpartitions using a second data distribution method.
In Hybrid Columnar Compression, a logical construct that stores a set of rows. When you load data into a table, the database stores groups of rows in columnar format, with the values for each column stored and compressed together. After the database has compressed the column data for a set of rows, the database fits the data into the compression unit.
Simultaneous access of the same data by many users. A multiuser database management system must provide adequate concurrency controls so that data cannot be updated or changed improperly, compromising data integrity.
See also data consistency.
The combination of one or more expressions and logical operators in a SQL statement that returns a value of TRUE, FALSE, or UNKNOWN. For example, the condition 1=1 always evaluates to TRUE.
Communication pathway between a client process and an Oracle database instance.
See also session.
A resource utilization and user scalability feature that maximizes the number of sessions over a limited number of protocol connections to a shared server.
A whole database backup that you can open with the RESETLOGS option without performing media recovery. In other words, the backup does not require the application of redo to be made consistent.
See also inconsistent backup.
A set of application-defined attributes that validates and secures an application. The SQL statement CREATE CONTEXT creates namespaces for contexts.
A binary file that records the physical structure of a database and contains the names and locations of redo log files, the time stamp of the database creation, the current log sequence number, checkpoint information, and so on.
An organization of measures with identical dimensions and other shared characteristics. The edges of the cube contain the dimension members, whereas the body of the cube contains the data values.
A handle or name for a private SQL area in the PGA. Because cursors are closely associated with private SQL areas, the terms are sometimes used interchangeably.
Organized collection of data treated as a unit. The purpose of a database is to store and retrieve related information. Every Oracle database instance accesses only one database in its lifetime.
The restriction of data access and database activities. For example, a database administrator can restrict users from querying specified tables or executing specified database commands.
A software program that interacts with a database to access and manipulate data.
The process by which a user presents credentials to the database, which verifies the credentials and allows access to the database.
The portion of the system global area (SGA) that holds copies of data blocks. All client processes concurrently connected to the instance share access to the buffer cache.
The combination of the system global area (SGA) and background processes. An instance is associated with one and only one database. In an Oracle Real Application Clusters configuration, multiple instances access a single database simultaneously.
In a schema object, a schema object in one database that enables users to access objects on a different database.
● database management system (DBMS)
Software that controls the storage, organization, and retrieval of data.
An object in the database that can be manipulated with SQL. Schema objects such as tables and indexes reside in schemas. Nonschema objects such as directories and roles do not reside in schemas.
The aspect of database administration that involves user authentication, encryption, access control, and monitoring.
A server that reliably manages a large amount of data in a multiuser environment so that users can concurrently access the same data. A database server also prevents unauthorized access and provides efficient solutions for failure recovery.
A named representation of one or more database instances. The service name for an Oracle database is normally its global database name. Clients use the service name to connect to one or more database instances.
A background process that writes buffers in the database buffer cache to data files.
Smallest logical unit of data storage in Oracle Database. Other names for data blocks include Oracle blocks or pages. One data block corresponds to a specific number of bytes of physical space on disk.
A consistent view of the data by each user in a multiuser database.
See also concurrency.
An error that occurs when a hardware, software, or network component causes corrupt data to be read or written.
A read-only collection of database tables and views containing reference information about the database, its structures, and its users.
A memory area in the shared pool that holds data dictionary information. The data dictionary cache is also known as the row cache because it holds data as rows instead of buffers, which hold entire data blocks.
A predefined view of tables or other views in the data dictionary. Data dictionary views begin with the prefix DBA_, ALL_, or USER_.
A physical file on disk that was created by Oracle Database and contains the data for a database. The data files can be located either in an operating system file system or Oracle ASM disk group.
Business rules that dictate the standards for acceptable data. These rules are applied to a database by using integrity constraints and triggers to prevent invalid data entry.
The automated search of large stores of data for patterns and trends that transcend simple analysis.
An Oracle Database infrastructure that automatically diagnoses persistent data failures, presents repair options to the user, and executes repairs at the user's request.
The segment containing the data for a nonclustered table, table partition, or table cluster.
See also extent.
In SQL, a fixed set of properties associated with a column value or constant. Examples include VARCHAR2 and NUMBER. Oracle Database treats values of different data types differently.
Data definition language. Includes statements such as CREATE TABLE or ALTER INDEX that define or change a data structure.
A situation in which two or more users are waiting for data locked by each other. Such deadlocks are rare in Oracle Database.
A database configuration in which a server process handles requests for a single client process.
See also shared server.
A constraint that permits a SET CONSTRAINT statement to defer constraint checking until after the transaction is committed. A deferrable constraint enables you to disable the constraint temporarily while making changes that might violate the constraint.
The number of parallel execution servers associated with a single operation. Parallel execution is designed to effectively use multiple CPUs. Oracle Database parallel execution framework enables you to either explicitly choose a specific degree of parallelism or to rely on Oracle Database to automatically control it.
In a schema object dependency, the object whose definition references another object. For example, if the definition of object A references object B, then A is a dependent object on B.
An index in which data is stored on a specified column or columns in descending order.
A structure that categorizes data to enable users to answer business questions. Commonly used dimensions are customers, products, and time.
A relational table that stores all or part of the values for a dimension in a star or snowflake schema. Dimension tables typically contain columns for the dimension keys, levels, and attributes.
An INSERT in which the database writes data directly to the data files, bypassing the database buffer cache. The database appends the inserted data to the existing data in the table.
A database object that specifies an alias for a directory on the server file system where external binary file LOBs (BFILEs) and external table data are located. All directory objects are created in a single namespace and are not owned by an individual schema.
A transaction reads data that has been written by another transaction that has not been committed yet. Oracle Database never permits dirty reads.
Optional background process present only when a shared server configuration is used. Each dispatcher process is responsible for routing requests from connected client processes to available shared server processes and returning the responses.
A set of databases in a distributed system that can appear to applications as a single data source.
The operations that occurs when an application distributes its tasks among different computers in a network.
A transaction that includes statements that, individually or as a group, update data on nodes of a distributed database. Oracle Database ensures the integrity of data in distributed transactions using the two-phase commit mechanism.
A private environment in which you can redefine database objects. Edition-based redefinition enables you to upgrade an application's database objects while the application is in use, thus minimizing or eliminating down time.
The process of transforming data into an unreadable format using a secret key and an encryption algorithm.
Extraction, transformation, and loading (ETL). The process of extracting data from source systems and bringing it into a data warehouse.
The combination of steps used by the database to execute a SQL statement. Each step either retrieves rows of data physically from the database or prepares them for the user issuing the statement. You can override execution plans by using hints.
A combination of one or more values, operators, and SQL functions that evaluates to a value. For example, the expression 2*2 evaluates to 4. In general, expressions assume the data type of their components.
Multiple contiguous data blocks allocated for storing a specific type of information. A segment is made up of one or more extents.
See also data block.
A read-only table whose metadata is stored in the database but whose data in stored in files outside the database. The database uses the metadata describing external tables to expose their data as if they were relational tables.
● extraction, transformation, and loading (ETL)
See ETL.
A table in a star schema of a data warehouse that contains factual data. A fact table typically has two types of columns: those that contain facts and those that are foreign keys to dimension tables.
A full index scan in which the database reads the index blocks in no particular order. The database accesses the data in the index itself, without accessing the table.
An optional disk location that stores recovery-related files such as control file and online redo log copies, archived redo log files, flashback logs, and RMAN backups.
An integrity constraint that requires each value in a column or set of columns to match a value in the unique or primary key for a related table. Integrity constraints for foreign keys define actions dictating database behavior if referenced data is altered.
A scan of an index in which the database reads the entire index in order.
A scan of table data in which the database sequentially reads all rows from a table and filters out those that do not meet the selection criteria. All data blocks under the high water mark are scanned.
A schema object, similar to a PL/SQL procedure, that always returns a single value.
An index that computes the value of a function or expression involving one or more columns and stores it in the index.
The basic unit of work in parallelism. Oracle Database divides the operation executed in parallel (for example, a table scan, table update, or index creation) into granules. Parallel execution processes execute the operation one granule at a time.
A computing architecture that coordinates large numbers of servers and storage to act as a single large computer.
The software that provides the infrastructure for an enterprise grid architecture. In a cluster, this software includes Oracle Clusterware and Oracle ASM. For a standalone server, this software includes Oracle Restart and Oracle ASM. Oracle Database 11g Release 2 (11.2) combines these infrastructure products into one software installation called the grid infrastructure home.
The steps performed by the database to build a new executable version of application code. The database must perform a hard parse instead of a soft parse if the parsed representation of a submitted statement does not exist in the shared pool.
A type of table cluster that is similar to an indexed cluster, except the index key is replaced with a hash function. No separate cluster index exists. In a hash cluster, the data is the index.
A function that operates on an arbitrary-length input value and returns a fixed-length hash value.
A join in which the database uses the smaller of two tables or data sources to build a hash table in memory. The database scans the larger table, probing the hash table for the addresses of the matching rows in the smaller table.
In a hash cluster, an actual or possible value inserted into the cluster key column. For example, if the cluster key is department_id, then hash key values could be 10, 20, 30, and so on.
An in-memory data structure that associates join keys with rows in a hash join. For example, in a join of the employees and departments tables, the join key might be the department ID. A hash function uses the join key to generate a hash value. This hash value is an index in an array, which is the hash table.
In a hash cluster, a unique numeric ID that identifies a bucket. Oracle Database uses a hash function that accepts an infinite number of hash key values as input and sorts them into a finite number of buckets. Each hash value maps to the database block address for the block that stores the rows corresponding to the hash key value (department 10, 20, 30, and so on).
A mathematical technique in which an infinite set of input values is mapped to a finite set of output values, called hash values. Hashing is useful for rapid lookups of data in a hash table.
A table in which the data rows are stored in no particular order on disk. By default, CREATE TABLE creates a heap-organized table.
A database that organizes data in a tree structure. Each parent record has one or more child records, similar to the structure of a file system.
The boundary between used and unused space in a segment.
An instruction passed to the optimizer through comments in a SQL statement. The optimizer uses hints to choose an execution plan for the statement.
An outage that occurs when unintentional or malicious actions are committed that cause data in the database to become logically corrupt or unusable.
A component of a DML statement that retrieves data without a subquery. An UPDATE, DELETE, or MERGE statement that does not explicitly include a SELECT statement uses an implicit query to retrieve the rows to be modified.
A backup in which some files in the backup contain changes made after the checkpoint. Unlike a consistent backup, an inconsistent backup requires media recovery to be made consistent.
Optional schema object associated with a nonclustered table, table partition, or table cluster. In some cases indexes speed data access.
An table cluster that uses an index to locate data. The cluster index is a B-tree index on the cluster key.
A measure of the row order in relation to an indexed value such as last name. The more order that exists in row storage for this value, the lower the clustering factor.
A table whose storage organization is a variant of a primary B-tree index. Unlike a heap-organized table, data is stored in primary key order.
An ordered scan of an index that has the following characteristics:
The retrieval of a row by traversing an index, using the indexed column values specified by the statement.
An index scan that uses logical subindexes of a composite index. The database "skips" through a single index as if it were searching separate indexes.
An index scan that must have either 0 or 1 rowid associated with an index key. The database performs a unique scan when a predicate references all of the columns in the key of a UNIQUE index using an equality operator.
A transaction that is running when an outage breaks the connection between a client application and the database.
A configuration parameter such as DB_NAME or SGA_TARGET that affects the operation of a database instance. Settings for initialization parameters are stored in a text-based initialization parameter file or binary server parameter file.
● initialization parameter file
A text file that contains initialization parameter settings for a database instance.
A join of two or more tables that returns only those rows that satisfy the join condition.
The combination of the system global area (SGA) and background processes. An instance is associated with one and only one database. In an Oracle Real Application Clusters configuration, multiple instances access a single database simultaneously.
The termination of a database instance because of a hardware failure, Oracle internal error, or SHUTDOWN ABORT statement.
The automatic application of redo log records to uncommitted data blocks when an instance is restarted after a failure.
See data integrity.
Declarative method of defining a rule for a column. The integrity constraints enforce business rules and prevent the entry of invalid information into tables.
● interested transaction list (ITL)
Information in the block header of every segment that determines whether a transaction was uncommitted when the database began modifying the block. Entries in the ITL describe which transactions have rows locked and which rows in the block contain committed and uncommitted changes.
An index that is maintained by DML operations, but is not used by default by the optimizer. Making an index invisible is an alternative to making it unusable or dropping it.
A statement that retrieves data from multiple tables specified in the FROM clause. Join types include inner joins, outer joins, and Cartesian joins.
A condition that compares two columns, each from a different table, in a join. The database combines pairs of rows, each containing one row from each table, for which the join condition evaluates to TRUE.
Column or set of columns included in the definition of certain types of integrity constraints.
The elimination of repeated occurrence of primary key column values in an index-organized table.
See LOB.
Optional area in the SGA that provides large memory allocations for backup and restore operations, I/O server processes, and session memory for the shared server and Oracle XA.
A low-level serialization control mechanism used to protect shared data structures in the SGA from simultaneous access.
In a B-tree index, a lower-level block that stores index entries. The upper-level branch blocks of a B-tree index contain index data that points to lower-level index blocks.
An area of memory in the shared pool. This cache includes the shared SQL areas, private SQL areas (in a shared server configuration), PL/SQL procedures and packages, and control structures such as locks and library cache handles.
A process that listens for incoming client connection requests and manages network traffic to the database.
A tablespace that uses a bitmap stored in each data file to manage the extents. In contrast, a dictionary-managed tablespace uses the data dictionary to manage space.
A database mechanism that prevents destructive interaction between transactions accessing a shared resource such as a table, row, or system object not visible to users. The main categories of locks are DML locks, DDL locks, and latches and internal locks.
A globally unique identifier that defines a transaction from the application perspective. The logical transaction ID is bound to the database transaction ID.
● logical volume manager (LVM)
A software package, available with most operating systems, that enables pieces of multiple physical disks to be combined into a single contiguous address space that appears as one disk to higher layers of software.
A number that uniquely identifies a set of redo records in a redo log file. When the database fills one online redo log file and switches to a different one, the database automatically assigns the new file a log sequence number.
The point at which the log writer (LGWR) stops writing to the active redo log file and switches to the next available redo log file. LGWR switches when either the active redo log file is filled with redo records or a switch is manually initiated.
The background process responsible for redo log buffer management—writing the redo log buffer to the online redo log. LGWR writes all redo entries that have been copied into the buffer since the last time it wrote.
A table containing a code column and an associated value column. For example, a job code corresponds to a job name. In contrast to a master table in a pair of master-detail tables, a lookup table is not the means to obtain a detailed result set, such as a list of employees. Rather, a user queries a table such as employees for an employee list and then joins the result set to the lookup table.
A data integrity problem in which one writer of data overwrites the changes of a different writer modifying the same data.
A mode of the database in which undo blocks are stored in user-managed undo segments. In automatic undo management mode, undo blocks are stored in a system-managed, dedicated undo tablespaces.
A detail table has a foreign key relationship with a master table. For example, the employees detail table has a foreign key to the departments master table. Unlike a lookup table, a master table is typically queried and then joined to the detail table. For example, a user may query a department in the departments table and then use this result to find the employees in this department.
In a replication environment, a different database with which a materialized view shares data.
The table associated with a materialized view at a master site.
A schema object that stores the result of a query. Oracle materialized views can be read-only or updatable.
See also view.
The application of redo or incremental backups to a data block or backup data file.
An instance that is started and has the database control file open.
An architecture in which one or more application servers provide data for clients and serves as an interface between clients and database servers.
A type of database, similar to a hierarchical database, in which records have a many-to-many rather than a one-to-many relationship.
● object-relational database management system (ORDBMS)
An RDBMS that implements object-oriented features such as user-defined types, inheritance, and polymorphism.
A schema object that abstracts a real-world entity such as a purchase order. Attributes model the structure of the entity, whereas methods implement operations an application can perform on the entity.
Online Analytical Processing. OLAP is characterized by dynamic, dimensional analysis of historical data.
Online Transaction Processing. OLTP systems are optimized for fast and reliable transaction handling. Compared to data warehouse systems, most OLTP interactions involve a relatively small number of rows, but a larger group of tables.
The set of two or more online redo log files that record all changes made to Oracle Database data files and control file. When a change is made to the database, Oracle Database generates a redo record in the redo buffer. log writer (LGWR) writes the contents of the redo buffer to the online redo log.
1. In memory management, operators control the flow of data. Examples include sort, hash join, and bitmap merge operators.
2. In SQL, an operator manipulates data items called operands or arguments and returns a result. The SQL operators are represented by special characters or by keywords. For example, the multiplication operator is represented by an asterisk (*).
Built-in database software that determines the most efficient way to execute a SQL statement by considering factors related to the objects referenced and the conditions specified in the statement.
● Oracle Automatic Storage Management (Oracle ASM)
See Oracle ASM.
Oracle Automatic Storage Management (Oracle ASM). A volume manager and a file system for database files. Oracle ASM is Oracle's recommended storage management solution, providing an alternative to conventional volume managers, file systems, and raw devices.
One or more Oracle ASM disks managed as a logical unit. I/O to a disk group is automatically spread across all the disks in the group.
A set of components that enables servers to operate together as if they were one server. Oracle Clusterware is a requirement for using Oracle RAC and it is the only clusterware that you need for platforms on which Oracle RAC operates.
A database security feature that controls when, where, and how databases, data, and applications are accessed.
A security feature that enables you to mask (redact) data that is returned from queries issued by low-privileged users or applications.
A system management tool that provides centralized management of an Oracle database environment.
Communication software that enables a network session between a client application and an Oracle database. After a network session is established, Oracle Net acts as a data courier for the client application and the database.
A process that resides on the server whose responsibility is to listen for incoming client connection requests and manage the traffic to the server. When a client requests a network session with a database, Oracle Net Listener (typically called the listener) receives the request. If the client information matches the listener information, then the listener grants a connection to the database server.
A suite of networking components that provide enterprise-wide connectivity solutions in distributed, heterogeneous computing environments. Oracle Net Services includes Oracle Net, listener, Oracle Connection Manager, Oracle Net Configuration Assistant, and Oracle Net Manager.
A process that runs Oracle Database code. Oracle processes include server processes and background processes.
Oracle Real Application Clusters. Option that allows multiple concurrent database instances to share a single physical database.
● Oracle Real Application Clusters
See Oracle RAC.
An implementation of the ANSI standard for SQL. Oracle SQL supports numerous features that extend beyond standard SQL.
● Oracle Virtual Private Database (VPD)
A security feature that enables you to create security policies to control database access at the row and column level. Essentially, VPD adds a dynamic WHERE clause to a SQL statement that is issued against the table, view, or synonym to which a VPD security policy was applied.
An external interface that allows global transactions to be coordinated by a transaction manager other than Oracle Database.
A join that returns all rows that satisfy the join condition and also returns some or all of those rows from one table for which no rows from the other satisfy the join condition.
The application of multiple CPU and I/O resources to the execution of a single database operation.
An index that is correlated with the indexing properties of an associated partitioned table.
A piece of a table or index that shares the same logical attributes as the other partitions. For example, all partitions in a table share the same column and constraint definitions.
A set of one or more columns that determines the partition in which each row in a partitioned table should go. Each row is unambiguously assigned to a single partition.
The ability to decompose very large tables and indexes into smaller and more manageable pieces called partitions.
Program global area. A memory buffer that contains data and control information for a server process.
See also SGA.
The physical rowid of an index entry when it was first made. Oracle Database can use physical guesses to probe directly into the leaf block of any index-organized table, bypassing the primary key search.
The part of the optimizer that tries different access paths, join methods, and join orders for a given query block to find the plan with the lowest cost.
Procedural Language/SQL. The Oracle Database procedural language extension to SQL. PL/SQL enables you to mix SQL statements with programmatic constructs such as procedures, functions, and packages.
A schema object that consists of a set of SQL statements and other PL/SQL constructs, grouped together, stored in the database, and run as a unit to solve a specific problem or perform a set of related tasks.
The total number of digits in a floating-point number. You specify a fixed-point number in the form NUMBER(p,s), where p represents the precision.
A programming tool that enables you to embed SQL statements in a high-level source program written in a language such as C, C++, or COBOL.
The column or set of columns that uniquely identifies a row in a table. Only one primary key can be defined for each table.
An integrity constraint that disallows duplicate values and nulls in a column or set of columns.
An area in memory that holds a parsed statement and other information for processing. The private SQL area contains data such as bind variable values, query execution state information, and query execution work areas.
The right to run a particular type of SQL statement, or the right to access an object that belongs to another user, run a PL/SQL package, and so on. The types of privileges are defined by Oracle Database.
A security mechanism that captures privilege usage for a database according to a specified condition. For example, you can find the privileges that a user exercised during a specific database session.
A mechanism in an operating system that can run a series of steps. By dividing the work of Oracle Database and database applications into several processes, multiple users and applications can connect to a single database instance simultaneously.
See also background process; Oracle process; client process.
See PGA.
An operation that retrieves data from tables or views. For example, SELECT * FROM employees is a query.
See also implicit query; subquery.
In parallel execution, the user session or shadow process that coordinates the parallel execution servers. The parallel execution servers performs each operation in parallel if possible. When the parallel servers are finished executing the statement, the query coordinator performs any portion of the work that cannot be executed in parallel. Finally, the query coordinator returns any results to the user.
The execution plan used to execute a query.
A consistent view of data seen by a user. For example, in statement-level read consistency the set of data seen by a SQL statement remains constant throughout statement execution.
See also concurrency; data consistency.
A class of errors that arise because of an external system failure, independently of the application session logic that is executing. Recoverable errors occur following planned and unplanned outages of networks, nodes, storage, and databases. An example of a nonrecoverable error is submission of invalid data values.
See RMAN.
SQL that the database executes in the background to obtain space for database objects. You can think of recursive SQL as "side effect" SQL.
A set of files that protect altered database data in memory that has not been written to the data files. The redo log can consist of two parts: the online redo log and the archived redo log.
Memory structure in the SGA that stores redo entries—a log of changes made to the database. The database writes the redo entries stored in the redo log buffers to an online redo log file, which is used if instance recovery is necessary.
A record in the online redo log that holds a group of change vectors, each of which describes a change made to a data block. Each redo log file consists of redo records.
The redo generated by a database instance.
In a schema object dependency, the object that is referenced by another object's definition. For example, if the definition of object A references object B, then B is a referenced object for A.
A rule defined on a key in one table that guarantees that the values in that key match the values in a key in a related table (the referenced value).
A database that conforms to the relational model, storing data in a set of simple relations.
● relational database management system (RDBMS)
A management system that moves data into a relational database, stores the data, and retrieves it so that applications can manipulate it.
A memory area in the shared pool that Oracle Database can use to allocate large contiguous chunks of memory.
A type of B-tree index that physically reverses the bytes of each index key while keeping the column order. For example, if the index key is 20, and if the two bytes stored for this key in hexadecimal are C1,15 in a standard B-tree index, then a reverse key index stores the bytes as 15,C1.
Recovery Manager. An Oracle Database utility that backs up, restores, and recovers Oracle databases.
A set of privileges that can be granted to database users or to other roles.
A set of column information corresponding to a single record in a table. The database stores rows in data blocks.
A situation in which Oracle Database must store a row in a series or chain of blocks because it is too large to fit into a single block.
A type of table storage in which all columns of one row are stored together, followed by all columns of the next row, and so on.
A situation in which Oracle Database moves a row from one data block to another data block because the row grows too large to fit in the original block.
A row is stored in a variable-length record. This record is divided into one or more row pieces. Each row piece has a row header and column data.
A set of interlinked schemas that enable Oracle documentation and Oracle instructional materials to illustrate common database tasks.
In a floating-point number, the number of digits from the decimal point to the least significant digit. You specify a fixed-point number in the form NUMBER(p,s), where s represents the scale.
A named collection of database objects, including logical structures such as tables and indexes. A schema has the name of the database user who owns it.
A logical structure of data stored in a schema. Examples of schema objects are tables, indexes, sequences, and database links.
The referencing of one object by another object. For example, a view contains a query that references tables or views, or a PL/SQL subprogram invokes other subprograms.
System Change Number. A database ordering primitive. The value of an SCN is the logical point in time at which changes are made to a database.
A set of methods for protecting a database from accidental or malicious destruction of data or damage to the database infrastructure.
A set of extents allocated for a specific database object such as a table, index, or table cluster. User segments, undo segments, and temporary segments are all types of segments.
In a query, the measure of how many rows from a row set pass a predicate test, for example, WHERE last_name = 'Smith'. A selectivity of 0.0 means no rows, whereas a value of 1.0 means all rows. A predicate becomes more selective as the value approaches 0.0 and less selective (or more unselective) as the value approaches 1.0.
A schema object that generates a serial list of unique numbers for table columns.
In a client/server architecture, the computer that runs Oracle software and handles the functions required for concurrent, shared data access. The server receives and processes the SQL and PL/SQL statements that originate from client applications.
A server-side binary file containing initialization parameter settings that is read and written to by the database.
An Oracle process that communicates with a client process and Oracle Database to fulfill user requests. The server processes are associated with a database instance, but are not part of the instance.
● service-oriented architecture (SOA)
A multitier architecture relying on services that support computer-to-computer interaction over a network.
A logical entity in the database instance memory that represents the state of a current user login to a database. A single connection can have 0, 1, or more sessions established on it.
System global area. A group of shared memory structures that contain data and control information for one Oracle database instance.
Portion of the SGA that contains shared memory constructs such as shared SQL areas.
A database configuration that enables multiple client processes to share a small number of server processes.
See also dedicated server.
An area in the shared pool that contains the parse tree and execution plan for a SQL statement. Only one shared SQL area exists for a unique statement.
A partitioning strategy that uses only one method of data distribution, for example, only list partitioning or only range partitioning.
The reuse of existing code when the parsed representation of a submitted SQL statement exists in the shared pool and can be shared.
See also hard parse.
A hash cluster that stores the rows corresponding to each value of the hash function in such a way that the database can efficiently return them in sorted order. The database performs the optimized sort internally.
Structured Query Language. A nonprocedural language to access a relational database. Users describe in SQL what they want done, and the SQL language compiler automatically generates a procedure to navigate the database and perform the task. Oracle SQL includes many extensions to the ANSI/ISO standard SQL language.
Oracle tool used to run SQL statements against Oracle Database.
An independent copy of a production database that you can use for disaster protection in a high availability environment.
A relational schema whose design represents a dimensional data model. The star schema consists of one or more fact tables and one or more dimension tables that are related through foreign keys.
See also dimension table; fact table.
A database operation in which the effects of an unsuccessful SQL statement are rolled back because the statement caused an error during execution.
A named PL/SQL block or Java program that Oracle Database stores in the database. Applications can call stored procedures by name.
● Structured Query Language (SQL)
See SQL.
A query nested within another SQL statement. Unlike implicit queries, subqueries use a SELECT statement to retrieve data.
In a data warehouse, an aggregate view that reduces query time by precalculating joins and aggregation operations and storing the results in a table.
An alias for a schema object. You can use synonyms to provide data independence and location transparency.
See SCN.
See SGA.
A schema object that contains data from one or more tables, all of which have one or more columns in common. In table clusters, the database stores together all the rows from all tables that share the same cluster key.
The compression of data segments to reduce disk space in a heap-organized table or table partition.
A user-defined PL/SQL function that returns a collection of rows (a nested table or varray). You can select from this collection as if it were a database table by invoking the table function inside the TABLE clause in a SELECT statement.
A database storage unit that groups related logical structures together. The database data files are stored in tablespaces.
A file that belongs to a temporary tablespace. The temp files in temporary tablespaces cannot contain permanent database objects.
A segment created by Oracle Database when a SQL statement needs a temporary database area to complete execution.
A table that holds an intermediate result set for the duration of a transaction or a session. Only the current session can see the data in temporary tables.
An administrative file that contain diagnostic data used to investigate problems. Oracle Database writes trace files to ADR.
Logical unit of work that contains one or more SQL statements. All statements in a transaction commit or roll back together. The use of transactions is one of the most important ways that a database management system differs from a file system.
An identifier is unique to a transaction and represents the undo segment number, slot, and sequence number.
A phase of instance recovery in which uncommitted transactions are rolled back.
The data structure within an undo segment that holds the transaction identifiers of the transactions using the undo segment.
A database feature that encrypts individual table columns or a tablespace. When a user inserts data into an encrypted column, the database automatically encrypts the data. When users select the column, the data is decrypted. This form of encryption is transparent, provides high performance, and is easy to implement.
A tablespace that you can copy or move between databases. Oracle Data Pump provides the infrastructure for transportable tablespaces.
A PL/SQL or Java procedure that fires when a table or view is modified or when specific user or database actions occur. Procedures are explicitly run, whereas triggers are implicitly run.
User global area. Session memory that stores session variables, such as logon information, and can also contain the OLAP pool.
Records of the actions of transactions, primarily before they are committed. The database can use undo data to logically reverse the effect of SQL statements. Undo data is stored in undo segments.
A segment in an undo tablespace.
A tablespace containing undo segments when automatic undo management mode is enabled.
A universal encoded character set that can store information in any language using a single character set.
A data type that can store all types of rowids. Oracle uses universal rowids to store the addresses of index-organized and non-Oracle tables.
An index that is not maintained by DML operations and is ignored by the optimizer. All indexes are usable (default) or unusable.
See UGA.
The name by which a user is known to Oracle Database and to other users. Every user name is associated with a password, and both must be entered to connect to Oracle Database.
See client process.
A named set of resource limits and password parameters that restrict database usage and database instance resources for a user.
A custom-tailored presentation of the data in one or more tables. The views do not actually contain or store data, but derive it from the tables on which they are based.
A column that is not stored on disk. The database derives the values in virtual columns on demand by computing a set of expressions or functions.
A backup of the control file and all data files that belong to a database.
Scripting on this page enhances content navigation, but does not change the content in any way.
GlossaryGlossary
A server designed to host applications and their environments, permitting server applications to run. A typical example is Oracle Application Server, which is able to host Java, C, C++, and PL/SQL applications in cases where a remote client controls the interface.
A property of an element that consists of a name and a value separated by an equals sign and contained within the start-tags after the element name. In this example, <Price units='USD'>5</Price>, units is the attribute and USD is its value, which must be in single or double quotes. Attributes may reside in the document or DTD. Elements may have many attributes but their retrieval order is not defined.
A programmatic technique in which one process starts another and then continues. The second process then calls the first as a result of an action, value, or other event. This technique is used in most programs that have a user interface to allow continuous interaction.
A stored program in Java or PL/SQL that adds the necessary functionality for the database to understand and manipulate a new datatype. Cartridges interface through the Extensibility Framework within Oracle Database version 8 or later. Oracle Text is such a cartridge, adding support for reading, writing, and searching text documents stored within the database.
A simple mechanism for adding style (fonts, colors, spacing, and so on) to Web documents.
Text in a document that should not be parsed is put within a CDATA section. This allows for the inclusion of characters that would otherwise have special functions, such as &, <, >, and so on. CDATA sections can be used in the content of an element or in attributes.
An element that is wholly contained within another, which is referred to as its parent element. For example <Parent><Child></Child></Parent> illustrates a child element nested within its parent element.
A utility that accepts an input file and creates a set of output classes that have corresponding functionality. In the case of the XML class generator, the input file is a DTD and the output is a series of classes that can be used to create XML documents conforming with the DTD.
The operating system environmental variable that the JVM uses to find the classes it needs to run applications.
● Common Object Request Broker API (CORBA)
An Object Management Group standard for communicating between distributed objects across a network. These self-contained software modules can be used by applications running on different platforms or operating systems. CORBA objects and their data formats and functions are defined in the Interface Definition Language (IDL), which can be compiled in a variety of languages including Java, C, C++, Smalltalk and COBOL.
● Common Oracle Runtime Environment (CORE)
The library of functions written in C that provides developers the ability to create code that can be easily ported to virtually any platform and operating system.
A text fragment, which may be in XML format, that is returned to the requester embedded in an HTML page from a SQL query processed by the XSQL Servlet.
The term used as the tag name designating the DTD or its reference within an XML document. For example, <!DOCTYPE person SYSTEM "person.dtd"> declares the root element name as person and an external DTD as person.dtd in the file system. Internal DTDs are declared within the DOCTYPE declaration.
An in-memory tree-based object representation of an XML document that enables programmatic access to its elements and attributes. The DOM object and its interface is a W3C recommendation. It specifies the Document Object Model of an XML Document including the APIs for programmatic access. DOM views the parsed document as a tree of objects.
● Document Type Definition (DTD)
A set of rules that define the legal structure of an XML document. DTDs are text files that derive their format from SGML and can either be included in an XML document by using the DOCTYPE element or by using an external file through a DOCTYPE reference.
The basic logical unit of an XML document that can serve as a container for other elements such as children, data, and attributes and their values. Elements are identified by start-tags, such as <name>, and end-tags, such as </name>, or in the case of empty elements, <name/>.
An element without text content or child elements. It can only contain attributes and their values. Empty elements are of the form <name/> or <name></name>, where there is no space between the tags.
An independent program module that runs within a JVM on the server. CORBA provides the infrastructure for EJBs, and a container layer provides security, transaction support, and other common functions on any supported server.
A string of characters that may represent either another string of characters or special characters that are not part of the document character set. Entities and the text that is substituted for them by the parser are declared in the DTD.
● eXtensible Markup Language (XML)
An open standard for describing data developed by the World Wide Web Consortium (W3C) using a subset of the SGML syntax and designed for Internet use.
● eXtensible Stylesheet Language (XSL)
The language used within stylesheets to transform or render XML documents. There are two W3C recommendations covering XSL stylesheets—XSL Transformations (XSLT) and XSL Formatting Objects (XSLFO).
XSL consists of two W3C recommendations: XSL Transformations for transforming one XML document into another and XSL Formatting Objects for specifying the presentation of an XML document. XSL is a language for expressing stylesheets. It consists of two parts:
-
A language for transforming XML documents (XSLT), and
-
An XML vocabulary for specifying formatting semantics (XSLFO).
An XSL stylesheet specifies the presentation of a class of XML documents by describing how an instance of the class is transformed into an XML document that uses the formatting vocabulary.
● eXtensible Stylesheet Language Formatting Object (XSLFO)
The W3C standard specification that defines an XML vocabulary for specifying formatting semantics. See FOP.
● eXtensible Stylesheet Language Transformation (XSLT)
Also written as XSL-T. The XSL W3C standard specification that defines a transformation language to convert one XML document into another.
Print formatter driven by XSL formatting objects. It is a Java application that reads a formatting object tree and then renders the resulting pages to a specified output. Output formats currently supported are , PCL, PS, SVG, XML (area tree representation), Print, AWT, MIF and TXT. The primary output target is .
XML Information Set, an abstract data set consisting of a number of information items. It has at least one information item: the document node, but the infoset is not necessarily valid XML. The W3C Recommendation is at http://www.w3.org/TR/xml-infoset/
An XML document validated against an XML schema. If the instance document conforms to the rules of the schema, then it is said to be valid.
A term used in object-based languages such as Java and C++ to refer to the creation of an object of a specific class.
● Integrated Development Environment (IDE)
A set of programs designed to aid in the development of software run from a single user interface. JDeveloper is an IDE for Java development, because it includes an editor, compiler, debugger, syntax checker, help system, and so on, to permit Java software development through a single user interface.
A high-level programming language developed and maintained by Sun Microsystems where applications run in a virtual machine known as a JVM. The JVM is responsible for all interfaces to the operating system. This architecture permits developers to create Java applications that can run on any operating system or platform that has a JVM.
● Java 2 Platform, Enterprise Edition (J2EE)
The Java platform (Sun Microsystems) that defines multitier enterprise computing.
● Java API for XML Processing (JAXP)
Enables applications to parse and transform XML documents using an API that is independent of a particular XML processor implementation.
● Java Architecture for XML Binding (JAXB)
API and tools that map to and from XML documents and Java objects. A JSR-31 recommendation.
An independent program module that runs within a JVM, typically for creating user interfaces on the client. Also known as Java Bean. The server equivalent is called an Enterprise JavaBean (EJB). See also Enterprise JavaBean.
● Java Database Connectivity (JDBC)
The programming API that enables Java applications to access a database through the SQL language. JDBC drivers are written in Java for platform independence but are specific to each database.
The collection of Java classes, runtime, compiler, debugger, and usually source code for a version of Java that makes up a Java development environment. JDKs are designated by versions, and Java 2 is used to designate versions from 1.2 onward.
● Java Naming and Directory Interface (JNDI)
A programming interface from Sun for connecting Java programs to naming and directory services such as DNS, LDAP, and NDS. Oracle XML DB Resource API for Java/JNDI supports JNDI.
● Java Runtime Environment (JRE)
The collection of complied classes that make up the Java virtual machine on a platform. JREs are designated by versions, and Java 2 is used to designate versions from 1.2 onward.
An extension to the servlet functionality that enables a simple programmatic interface to Web pages. JSPs are HTML pages with special tags and embedded Java code that is executed on the Web server or application server providing dynamic functionality to HTML pages. JSPs are actually compiled into servlets when first requested and run in the JVM of the server.
● Java Specification Request (JSR)
A recommendation of the Java Community Process organization (JCP), such as JAXB.
The Java interpreter that converts the compiled Java bytecode into the machine language of the platform and runs it. JVMs can run on a client, in a browser, in a middle tier, on an intranet, on an application server, or in a database server.
Oracle Java IDE that enables application, applet, and servlet development and includes an editor, compiler, debugger, syntax checker, help system, an integrated UML class modeler, and so on. JDeveloper has been enhanced to support XML-based development by including the Oracle Java XDK components, integrated for use along with XML support, in its editor.
The process of traversing a Java content tree and writing an XML document that reflects the content of the tree. It is the inverse of unmarshalling.
● notation attribute declaration
In XML, the declaration of a content type that is not part of those understood by the parser. These types include audio, video, and other multimedia.
The Oracle Application Server product integrates all the core services and features required for building, deploying, and managing high-performance, n-tier, transaction-oriented Web applications within an open standards framework.
● Oracle Content Management SDK
The Oracle file system and Java-based development environment that either runs inside the database or on a middle tier and provides a means of creating, storing, and managing multiple types of documents in a single database repository.
An Oracle tool that provides full-text indexing of documents and the capability to do SQL queries over documents, along with XPath-like searching.
A high-performance XML storage and retrieval technology provided with Oracle database server. It is based on the W3C XML data model.
● Oracle XML Developer's Kit (XDK)
The set of libraries, components, and utilities that provide software developers with the standards-based functionality to XML-enable their applications. In the case of the Oracle Java components of XDK, the kit contains an XML parser, an XSLT processor, the XML class generator, the JavaBeans, and the XSQL Servlet.
The operating system environment variable that identifies the location of the Oracle database installation for use by applications.
● Organization for the Advancement of Structured Information (OASIS)
An organization of members chartered with promoting public information standards through conferences, seminars, exhibits, and other educational events. XML is a standard that OASIS is actively promoting as it is doing with SGML.
An element that surrounds another element, which is referred to as its child element. For example, <Parent><Child></Child></Parent> illustrates a parent element wrapping its child element.
● parsed character data (PCDATA)
The element content consisting of text that should be parsed but is not part of a tag or nonparsed data.
The name of a resource that reflects its location in the repository hierarchy. A path name is composed of a root element (the first /), element separators (/) and various sub-elements (or path elements). A path element may be composed of any character in the database character set except ("\", "/" ). These characters have a special meaning for Oracle XML DB. Forward slash is the default name separator in a path name and backward slash may be used to escape characters.
An entity that may be granted access control privileges to an Oracle XML DB resource. Oracle XML DB supports as principals:
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Database users.
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Database roles. A database role can be understood as a group, for example, the DBA role represents the DBA group of all the users granted the DBA role.
Users and roles imported from an LDAP server are also supported as a part of the database general authentication model.
The opening part of an XML document containing the XML declaration and any DTD or other declarations needed to process the document.
The set of database objects, in any schema, that are mapped to path names. There is one root to the repository ("/") which contains a set of resources, each with a path name.
The name of a resource within its parent folder. Resource names must be unique (potentially subject to case-insensitivity) within a folder. Resource names are always in the UTF-8 character set (NVARCHAR2).
The element that encloses all the other elements in an XML document and is between the optional prolog and epilog. An XML document is only permitted to have one root element.
The definition of the structure and data types within a database. It can also be used to refer to an XML document that support the XML Schema W3C recommendation.
A Java application that runs in a server, typically a Web or application server, and performs processing on that server. Servlets are the Java equivalent to CGI scripts.
An XML standard interface provided by XML parsers and used by event-based applications.
● Simple Object Access Protocol (SOAP)
An XML-based protocol for exchanging information in a decentralized, distributed environment.
An ANSI specification for representing XML in SQL. Oracle SQL includes SQL/XML functions that query XML. The specification is not yet completed.
● Structured Generalized Markup Language (SGML)
An ISO standard for defining the format of a text document implemented using markup and DTDs.
● Structured Query Language (SQL)
The standard language used to access and process data in a relational database.
In XML, the term used to describe an XML document that consists of XSL processing instructions used by an XSLT processor to transform or format an input XML document into an output one.
A single piece of XML markup that delimits the start or end of an element. Tags start with < and end with >. In XML, there are start-tags (<name>), end-tags (</name>), and empty tags (<name/>).
TransX Utility is a Java API that simplifies the loading of translated seed data and messages into a database.
The process of reading an XML document and constructing a tree of Java content objects. Each content object corresponds directly to an instance in the input document of the corresponding schema component.
See Also: marshalling
A set of technologies that constitute a framework for building Web applications.
The term used to refer to an XML document when its structure and element content is consistent with that declared in its associated DTD or XML schema.
The term used to refer to an XML document that conforms to the syntax of the XML version declared in its XML declaration. This includes having a single root element, properly nested tags, and so forth.
The committee within the W3C that is made up of industry members that implement the recommendation process in specific Internet technology areas.
● World Wide Web Consortium (W3C)
An international industry consortium started in 1994 to develop standards for the World Wide Web. It is located at http://www.w3c.org.
● World Wide Web Distributed Authoring and Versioning (WebDAV)
The Internet Engineering Task Force (IETF) standard for collaborative authoring on the Web. Oracle XML DB Foldering and Security features are WebDAV-compliant.
An XML element defined by the Oracle XML DB schema that contains binary data. XDBbinary elements are stored in the repository when completely unstructured binary data is uploaded into Oracle XML DB.
The XML Linking language consisting of the rules governing the use of hyperlinks in XML documents. These rules are being developed by the XML Linking Group under the W3C recommendation process. This is one of the three languages XML supports to manage document presentation and hyperlinks (XLink, XPointer, and XPath).
A W3C recommendation that describes the use of the xml:base attribute, which can be inserted in an XML document to specify a base URI other than the base URI of the document or external entity. The URIs in the document are resolved by means of the given base.
A set of services that allows for integration with the Oracle E-Business Suite to create and consume XML messages triggered by business events.
The term to describe a set of related element names or attributes within an XML document. The namespace syntax and its usage is defined by a W3C Recommendation. For example, the <xsl:apply-templates/ > element is identified as part of the XSL namespace. Namespaces are declared in the XML document or DTD before they are used, with the following attribute syntax: xmlns:xsl="http://www.w3.org/TR/WD-xsl".
In XML, a software program that receives an XML document and determines whether it is well-formed and, optionally, valid. The Oracle XML parser supports both SAX and DOM interfaces.
● XML Pipeline Definition Language
W3C recommendation that enables you to describe the processing relations between XML resources.
A software program that reads an XML document and processes it, that is, performs actions on the document based on a set of rules. Validity checkers and XML editors are examples of processors.
The on-going effort of the W3C to create a standard for the language and syntax to query XML documents.
See XML Schema language.
Equivalent to XML Schema language.
The XML Schema language, also called simply "XML Schema," is a W3C standard for the use of simple data types and complex structures within an XML document. It addresses areas currently lacking in DTDs, including the definition and validation of data types.
Oracle XML Schema processor automatically ensures validity of XML documents and data used in e-business applications, including online exchanges. It adds simple and complex datatypes to XML documents and replaces DTD functionality with an XML schema definition XML document.
● XMLSchema-instance namespace
Used to identify an instance document as a member of the class defined by a particular XML schema. You must declare the XMLSchema-instance namespace by adding a namespace declaration to the root element of the instance document. For example: xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance.
This Oracle utility can generate an XML document (string or DOM) given a SQL query or a JDBC ResultSet object. XSU can also extract the data from an XML document, then insert, update, or delete rows in a database table.
XMLType is an Oracle datatype that stores XML data using an underlying CLOB column, or object-relational columns, or a binary format within a table or view.
Oracle XML DB provides a way to wrap existing relational and object-relational data in XML format. This is especially useful if, for example, your legacy data is not in XML but you have to migrate it to an XML format.
The open standard syntax for addressing elements within a document used by XSL and XPointer. XPath is currently a W3C recommendation. It specifies the data model and grammar for navigating an XML document utilized by XSLT, XLink and XML Query.
The term and W3C recommendation to describe a reference to an XML document fragment. An XPointer can be used at the end of an XPath-formatted URI. It specifies the identification of individual entities or fragments within an XML document using XPath navigation.
Oracle's XSLT Virtual Machine is the software implementation of a "CPU" designed to run compiled XSLT code. The concept of virtual machine assumes a compiler compiling XSLT stylesheets to a program of byte-codes, or machine instructions for the "XSLT CPU".
A Java-based servlet that can dynamically generate XML documents from one or more SQL queries and optionally transform the documents in the server with an XSLT stylesheet.
Scripting on this page enhances content navigation, but does not change the content in any way.
GlossaryGlossary
A feature of Oracle Connection Manager that sets rules for denying or allowing certain clients to access designated servers.
The group of access directives that you define. The directives grant levels of access to specific data for specific clients or groups of clients.
See protocol address.
An alternative name for a network object in an Oracle Names server. An alias stores the name of the object is referencing. When a client requests a lookup of an alias, Oracle completes the lookup as if it is the referenced object.
A host computer that runs the Oracle Net Firewall Proxy. An application gateway looks and acts like a real server from the client's point of view, and a real client from the server's point of view. An application gateway sits between the Internet and company's internal network and provides middleman services (or proxy services) to users on either side.
American Standard Code for Information Interchange character set, a convention for representing alphanumeric information using digital data. The collation sequence used by most computers with the exception of IBM and IBM-compatible computers.
A piece of information that describes some aspect of a directory entry. An entry comprises a set of attributes, each of which belongs to an object class. Moreover, each attribute has both a type, which describes the kind of information in the attribute, and a value which contains the actual data.
A security method that enables you to have confidence in the identity of users, clients, and servers in distributed environments. Network authentication methods can also provide the benefit of single sign-on for users. The following authentication methods are supported in Oracle Database, depending on whether Oracle Advanced Security is installed:
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RADIUS
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Kerberos
● Automatic Diagnostic Repository (ADR)
A systemwide tracing and logging central repository. The repository is a file-based hierarchical data store for depositing diagnostic information, including network tracing and logging information.
Memory that stores recently-accessed data to so that subsequent requests to access the same data can be processed quickly.
A user, software application, or computer that requests the services, data, or processing from another application or computer. The client is the user process.
Load balancing, whereby if more than one listener services a single database, a client can randomly choose between the listeners for its connect requests. This randomization enables all listeners to share the burden of servicing incoming connect requests.
The properties of a client, which may include the preferred order of naming methods, client and server logging and tracing, the domain from which to request names, and other client options for Oracle Advanced Security.
Software architecture based on a separation of processing between two CPUs. One CPU acts as the client in the transaction, requesting and receiving services. The other acts as the server that provides service for the requests.
A configuration file that specifies protocol addresses for incoming requests and administrative commands, as well as Oracle Connection Manager parameters and access control rules.
● CMADMIN (Connection Manager Administration)
An Oracle Connection Manager process that monitors the health of the listener and Oracle Connection Manager gateway processes, shutting down and starting processes as needed. CMADMIN registers information about gateway processes with the listener and processes commands executed with the Oracle Connection Manager Control utility.
● CMGW (Connection Manager gateway)
An Oracle Connection Manager process that receives client connections screened and forwarded by the listener located at the Oracle Connection Manager instance. The gateway process forwards the requests to the database server. In addition, it can multiplex or process multiple client connections through a single protocol connection.
A portion of the connect descriptor that defines the destination database service name or Oracle System Identifier (SID). In the following example, SERVICE_NAME defines a database service called sales.us.example.com:
(DESCRIPTION= (ADDRESS=(PROTOCOL=tcp)(HOST=sales-server)(PORT=1521) (CONNECT_DATA= (SERVICE_NAME=sales.us.example.com)))
A specially-formatted description of the destination for a network connection. A connect descriptor contains destination service and network route information.
The destination service is indicated by using its service name. The network route provides, at a minimum, the location of the listener through use of a network address.
A name, net service name, or service name that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a connect identifier in a connect string for the service to which they want to connect, for example:
CONNECT username@connect_identifier
Information the user passes to a service to connect, such as user name, password, and connect identifier:
CONNECT username@net_service_name
A connect-time failover occurs when a client connect request fails over to a different address if the first protocol address fails. A statically configured global database name disables connect-time failover.
An interaction between two processes on a network. Connections are originated by an initiator (client) that requests a connection with a destination (server).
The method for balancing the number of active connections for the same service across the instances and dispatchers. Connection load balancing enables listeners to make routing decisions based on how many connections for each dispatcher and the load on the nodes.
A resource utilization and user scalability feature that enables you to maximize the number of sessions over a limited number of protocol connections to a shared server.
A notification sent by an initiator and received by a listener that indicates that the initiator wants to start a connection.
See packet.
● database administrator (DBA)
A person responsible for operating and maintaining an Oracle Server or a database application.
An Oracle user name that has been given DBA privileges and can perform database administration functions. Usually the two meanings coincide. Many sites have multiple DBAs.
● Database Configuration Assistant
A tool that enables you to create, delete, and modify a database.
A pointer that defines a one-way communication path from an Oracle database server to another database server. The link is a defined entry in a data dictionary table. To access the link, the user must be connected to the local database that contains the data dictionary entry.
A client connected to local database A can use a link stored in database A to access information in remote database B. However, users connected to database B cannot use the same link to access data in database A. If local users on database B want to access data on database A, then a link must be defined and stored in the data dictionary of database B.
The following database links are supported:
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A private database link in a specific schema of a database. Only the owner of a private database link can use it.
-
A public database link for a database. All users in the database can use it.
A server process that is dedicated to one client connection. Compare to shared server.
The domain within which most client requests take place. It could be the domain where the client resides, or it could be a domain from which the client requests network services often. Default domain is also the client configuration parameter that determines what domain should be appended to unqualified network name requests. A name request is unqualified if it does not have a period (.) character within it.
● directory information tree (DIT)
A hierarchical tree-like structure in a directory server of the distinguished names (DNs) of the entries.
A naming method that resolves a database service, net service name, or net service alias to a connect descriptor stored in a central directory server. A directory server provides central administration of directory naming objects, reducing the work effort associated with adding or relocating services.
A directory server that is accessed with the Lightweight Directory Access Protocol (LDAP). Support of LDAP-compliant directory servers provides a centralized vehicle for managing and configuring a distributed Oracle network. The directory server can replace client-side and server-side localized tnsnames.ora files.
A process that enables many clients to connect to the same server without the need for a dedicated server process for each client. A dispatcher handles and directs multiple incoming network session requests to shared server processes. See also shared server.
Name of entry in a directory server. The DN specifies where the entry resides in the LDAP directory hierarchy, much the way a directory path specifies the exact location of a file.
Division of front-end and back-end processing to different computers. Oracle Net Services support distributed processing by transparently connecting applications to remote databases.
Any tree or subtree within the Domain Name System (DNS) namespace. Domain most commonly refers to a group of computers whose host names share a common suffix, the domain name.
A system for naming computers and network services that is organized into a hierarchy of domains. DNS is used in TCP/IP networks to locate computers through user-friendly names. DNS resolves a friendly name into an IP address, which is understood by computers.
For Oracle Net Services, DNS translates the host name in a TCP/IP address into an IP address.
An enterprise role is analogous to a regular database role, except that it spans authorization on multiple databases. An enterprise role is a category of roles that define privileges on a particular database. An enterprise role is created by the database administrator of a particular database. An enterprise role can be granted to or revoked to one or more enterprise users. The information for granting and revoking these roles is stored in the directory server.
A user that has a unique identity across an enterprise. Enterprise users connect to individual databases through a schema. Enterprise users are assigned enterprise roles that determine their access privileges on databases.
The building block of a directory server, it contains information about an object of interest to directory users.
A naming method that uses a third-party naming service, such as NIS.
Function or procedure written in a third-generation language (3GL) that can be called from PL/SQL code. Only C is supported for external procedures.
See access control.
The set of domains not managed within a given administrative region. Domains are foreign only in relation to a region; they are not foreign in any absolute sense. A network administrator typically defines foreign domains relative to a particular region to optimize caching performance.
File Transfer Protocol. A client/server protocol which allows a user on one computer to transfer files to and from another computer over a TCP/IP network.
The full name of the database which uniquely identifies it from any other database. The global database name is of the form "database_name.database_domain," for example, sales.us.example.com.
The database name portion, sales, is a simple name to call a database. The database domain portion, us.example.com, specifies the database domain in which the database is located, making the global database name unique. When possible, Oracle recommends that your database domain mirror the network domain.
The global database name is the default service name of the database, as specified by the SERVICE_NAMES parameter in the initialization parameter file.
An integrated component that provides the generic technology for accessing non-Oracle systems from the Oracle database server. Heterogeneous Services enables you to:
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Use Oracle SQL to transparently access data stored in non-Oracle systems as if the data resides within an Oracle server.
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Use Oracle procedure calls to transparently access non-Oracle systems, services, or application programming interfaces (APIs), from your Oracle distributed environment.
An infrastructure in which names are divided into multiple hierarchically-related domains. For Oracle Names, hierarchical naming model can be used with either central or delegated administration.
A naming method resolution that enables users in a TCP/IP environment to resolve names through their existing name resolution service. This name resolution service might be Domain Name System (DNS), Network Information Service (NIS), or simply a centrally-maintained set of /etc/hosts files. Host naming enables users to connect to an Oracle database server by simply providing the server computer's host name or host name alias. No client configuration is required to take advantage of this feature. This method is recommended for simple TCP/IP environments.
Hypertext Transfer Protocol. A protocol that provides the language that enables Web browsers and application Web servers to communicate.
A collection of identities, all of which are governed by the same administrative policies. In an enterprise, all employees having access to the intranet may belong to one realm, while all external users who access the public applications of the enterprise may belong to another realm. An identity management realm is represented in the directory by a specific entry with a special object class associated with it.
The combination of the System Global Area (SGA) and the Oracle background processes. When a database is started on a database server (regardless of the type of computer), Oracle allocates a memory area called the SGA, and starts one or more Oracle processes. The memory and processes of an instance efficiently manage the associated database data and serve the database users. You can connect to any instance to access information within a cluster database.
A name of an Oracle database instance. The instance name is identified by the INSTANCE_NAME parameter in the database initialization parameter file. INSTANCE_NAME corresponds to the Oracle System Identifier (SID) of the instance. Clients can connect to a specific instance by specifying the INSTANCE_NAME parameter in the connect descriptor.
The instance name is included in the connect data part of the connect descriptor.
● Interprocess Communication (IPC)
A protocol used by client applications that resides on the same node as the listener to communicate with the database. IPC can provide a faster local connection than TCP/IP.
Used to identify a node on a network. Each computer on the network is assigned a unique IP address, which is made up of the network ID, and a unique host ID. This address is typically represented in dotted-decimal notation, with the decimal value of each octet separated by a period, for example 192.168.2.22.
● Java Database Connectivity (JDBC) Driver
A driver that provides Java applications and applets access to an Oracle database.
A Type II driver for use with client/server Java applications. This driver requires an Oracle client installation.
A Type IV driver for Oracle JDBC applets and applications. Because it is written entirely in Java, this driver is platform-independent. It does not require any additional Oracle software on the client side. The Thin driver communicates with the server using Two-Task Common (TTC), a protocol developed by Oracle to access the database server.
The combination of a keyword and a value, used as the standard unit of information in connect descriptors and many configuration files. Keyword-value pairs may be nested; that is, a keyword may have another keyword-value pair as its value.
● LDAP Data Interchange Format (LDIF)
The set of standards for formatting an input file for any of the LDAP command line utilities.
A file created by Oracle Internet Directory Configuration Assistant or Oracle Net Configuration Assistant that contains the following directory server access information:
-
Type of directory server
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Location of the directory server
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Default Oracle Context that the client or server use to look up or configure connect identifiers for connections to database services
When created with Oracle Internet Directory Configuration Assistant, ldap.ora is located in the ORACLE_HOME/ldap/admin directory. When created with Oracle Net Configuration Assistant, ldap.ora is located in the ORACLE_HOME/network/admin directory.
● Lightweight Directory Access Protocol (LDAP)
A standard, extensible directory access protocol. It is a industry-standard programmatic interface and a wire protocol which enables clients to access directory systems.
An extension to the database link name which specifies the connect name used to connect to the database. It provides alternate settings for the database user name and password credentials. For example, a link qualifier of fieldrep can be appended to a global database link of sales.us.example.com.
SQL> SELECT * FROM emp@sales.us.example.com@fieldrep
A process that resides on the server whose responsibility is to listen for incoming client connection requests and manage the traffic to the server.
When a client requests a network session with a database server, a listener receives the actual request. If the client information matches the listener information, then the listener grants a connection to the database server.
A utility included with Oracle Net Services to control listener functions, such as starting, stopping, and getting the status of the listener.
A configuration file for the listener that identifies the following for a listener:
-
Unique name
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Protocol addresses that it is accepting connection requests on
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Services it is listening for
The listener.ora file typically resides in the ORACLE_HOME/network/admin directory.
Oracle does not require identification of the database service because of service registration. However, static service configuration is required if you plan to use Oracle Enterprise Manager.
A feature by which client connections are distributed evenly among multiple listeners, dispatchers, instances, and nodes so that no single component is overloaded.
Oracle Net Services support client load balancing and connection load balancing.
A naming method that locates network addresses by using information configured and stored on each individual client's tnsnames.ora file. Local naming is most appropriate for simple distributed networks with a small number of services that change infrequently.
A distributed database characteristic that enables applications to access data tables without knowing where they reside. All data tables appear to be in a single database, and the system determines the actual data location based on the table name. The user can reference data on multiple nodes in a single statement, and the system automatically and transparently routes (parts of) SQL statements to remote nodes for execution if needed. The data can move among nodes with no impact on the user or application.
A feature in which errors, service activity, and statistics are written to a log file. The log file provides additional information for an administrator when the error message on the screen is inadequate to understand the failure. The log file, by way of the error stack, shows the state of the software at various layers.
See also tracing.
A connection from the server back to itself. Performing a successful loopback verifies that Oracle Net is functioning on the database server.
Files used by the Network Information Service (NIS) ypserv program to handle name requests.
An LDAP-compliant directory server included with Microsoft Windows 2000 Server. It stores information about objects on the network, and makes this information available to users and network administrators. Active Directory also provides access to resources on the network using a single logon process.
Active Directory can be configured as a directory naming method to store service information that clients can access.
● Microsoft Windows NT native authentication
An authentication method that enables a client single login access to a Microsoft Windows NT server and a database running on the server.
A high-level interface protocol providing interprocess communications between clients and servers using distributed applications. Named Pipes enables client/server conversation over a network using Named Pipes protocol.
A subtree that resides entirely on one directory server. It is a contiguous subtree, that is, it must begin at an entry that serves as the top of the subtree, and extend downward to either leaf entries or references to subordinate naming contexts. It can range in size from a single entry to the entire directory information tree (DIT).
An Oracle Context can be created under a naming context.
The resolution method used by a client application to resolve a connect identifier to a connect descriptor when attempting to connect to a database service. Oracle Net provides four naming methods:
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Easy Connect naming
An alternative name for a directory naming object in a directory server. A directory server stores net service aliases for any defined net service name or database service. A net service alias entry does not have connect descriptor information. Instead, it only references the location of the object for which it is an alias. When a client requests a directory lookup of a net service alias, the directory determines that the entry is a net service alias and completes the lookup as if it was actually the entry it is referencing.
A simple name for a service that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a net service name in a connect string for the service to which they want to connect:
CONNECT username/password@net_service_name
Depending on your needs, net service names can be stored in a variety of places, including:
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Local configuration file, tnsnames.ora, on each client
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Directory server
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External naming service, such as NIS
A group of two or more computers linked through hardware and software to allow the sharing of data and peripherals.
The person who performs network management tasks such as installing, configuring, and testing network components. The administrator typically maintains the configuration files, connect descriptors and service names, aliases, and public and global database links.
As defined by Oracle, the set of characters acceptable for use as values in keyword-value pairs (that is, in connect descriptors and configuration files). The set includes alphanumeric uppercase, and lowercase, and some special characters.
● Network Information Service (NIS)
Sun Microsystems' Yellow Pages (yp) client/server protocol for distributing system configuration data such as user and host names between computers on a network.
A network layer that provides a generic interface for Oracle clients, servers, or external processes to access Oracle Net functions. The NI layer handles the break and reset requests for a connection.
See listener.
● Network Program Interface (NPI)
An interface for server-to-server interactions that performs all of the functions that the OCI does for clients, allowing a coordinating server to construct SQL requests for additional servers.
A session layer that is used in typical Oracle Net connections to establish and maintain the connection between a client application and a database server.
See Network Session (NS).
Network Transport. See transport.
In a directory server, a named group of attributes. When you want to assign attributes to an entry, you do so by assigning the object classes that hold those attributes to that entry.
All objects associated with the same object class share the attributes of that object class.
● Open Systems Interconnection (OSI)
A network architecture model developed by ISO as a framework for international standards in heterogeneous computer network architecture.
The OSI architecture has seven layers, from lowest to highest:
1. Physical layer
2. Data link layer
3. Network layer
4. Transport layer
5. Session layer
6. Presentation layer
7. Application layer
A comprehensive suite of security features to protect enterprise networks and securely extends corporate networks to the Internet. Oracle Advanced Security provides a single source of integration with network encryption and authentication solutions, single sign-on services, and security protocols. By integrating industry standards, it delivers unparalleled security to the network.
An application programming interface (API) that enables you to create applications that use the native procedures or function calls of a third-generation language to access an Oracle database server and control all phases of SQL statement execution. OCI supports the data types, calling conventions, syntax, and semantics of a number of third-generation languages including C, C++, COBOL and FORTRAN.
A router through which a client connection request may be sent either to its next hop or directly to the database server. Clients who route their connection requests through an Oracle Connection Manager can take advantage of the session multiplexing, access control, or protocol conversion features configured for that Oracle Connection Manager.
● Oracle Connection Manager Control utility
A utility included with Oracle Net Services to control various functions, such as starting, stopping, and getting the status of the Oracle Connection Manager.
A relative distinguished name (RDN) of cn=OracleContext in a directory information tree (DIT) that is located under a naming context or an unpublished directory entry. Oracle Context contains entries for use with Oracle features, such as Oracle Net directory naming and Oracle Advanced Security enterprise user security. There can be one or more Oracle Contexts in a directory server. Oracle Internet Directory automatically creates an Oracle Context at the root of the DIT structure. This root Oracle Context has a DN of dn:cn=OracleContext.
A separate Oracle product that combines a graphical console, agents, common services, and tools to provide an integrated and comprehensive systems management platform for managing Oracle products.
An infrastructure enabling deployments to manage centrally and securely all enterprise identities and their access to various applications in the enterprise.
A directory server implemented as an application on the Oracle database. It enables retrieval of information about dispersed users and network resources. It combines Lightweight Directory Access Protocol (LDAP) Version 3, the open Internet standard directory server access protocol, with the high performance, scalability, robustness, and availability of the Oracle database.
Communication software that enables a network session from a client application to an Oracle database server. After a network session is established, Oracle Net acts as a data courier for the client application and the database server. It is responsible for establishing and maintaining the connection between the client application and database server, as well as exchanging messages between them. Oracle Net can perform these jobs because it is located on each computer in the network.
● Oracle Net Configuration Assistant
A postinstallation tool that configures basic network components after installation, including:
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Listener names and protocol addresses
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Naming methods the client uses to resolve connect identifiers
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Net service names in a tnsnames.ora file
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Directory server usage
Product offered by some firewall vendors that supplies Oracle Connection Manager functionality.
A networking communication layer that is responsible for establishing and maintaining the connection between the client application and server, as well as exchanging messages between them.
See listener.
A tool that combines configuration abilities with component control to provide an integrated environment for configuring and managing Oracle Net Services.
You can use Oracle Net Manager to configure the following network components:
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Naming
Define connect identifiers and map them to connect descriptors to identify the network location and identification of a service. Oracle Net Manager supports configuration of connect descriptors in a local tnsnames.ora file or directory server.
-
Naming Methods
Configure the ways in which connect identifiers are resolved into connect descriptors.
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Listeners
Create and configure listeners to receive client connections.
A suite of networking components that provide enterprise-wide connectivity solutions in distributed, heterogeneous computing environments. Oracle Net Services is comprised of Oracle Net, listener, Oracle Connection Manager, Oracle Net Configuration Assistant, and Oracle Net Manager.
● Oracle Program Interface (OPI)
A networking layer responsible for responding to each of the possible messages sent by OCI. For example, an OCI request to fetch 25 rows would have an OPI response to return the 25 rows after they have been fetched.
A software layer responsible for mapping Transparent Network Substrate (TNS) functionality to industry-standard protocols used in the client/server connection.
A database for Digital's 64-bit platforms. Because Oracle Rdb has its own listener, the client interacts with Rdb in the same manner as it does with an Oracle database.
A set of rules that determine what can be stored in a directory server. Oracle has its own schema that is applied to many types of Oracle entries, including Oracle Net Services entries. The Oracle schema for Oracle Net Services entries includes the attributes the entries may contain.
● Oracle System Identifier (SID)
A name that identifies a specific instance of a running an Oracle database earlier than release 8.1. For any database, there is at least one instance referencing the database.
For Oracle databases earlier than release 8.1, a SID is used to identify the database. The SID is included in the connect descriptor of a tnsnames.ora file and in the definition of the listener in the listener.ora file.
A high-performance XML storage and retrieval technology provided with Oracle database server. It is based on the W3C XML data model.
● Oracle Real Application Clusters
An architecture that allows multiple instances to access a shared database of data files. Oracle Real Application Clusters is also a software component that provides the necessary cluster database scripts, initialization files, and data files needed for the Oracle Enterprise Edition and Oracle Real Application Clusters.
An alternate name for the top directory in the Oracle directory hierarchy on some directory-based operating systems.
A block of information sent over the network each time a connection or data transfer is requested. The information contained in packets depends on the type of packet, such as connect, accept, redirect, data, and so on. Packet information can be useful in troubleshooting.
A process monitor (PMON) database process that performs process recovery when a user process fails. PMON is responsible for cleaning the cache and freeing resources that the process was using. PMON also checks on dispatcher and server processes and restarts them if they have failed. As a part of service registration, PMON registers instance information with the listener.
A networking communication layer that manages the representation of information that application layer entities either communicate or reference in their communication. Two-Task Common (TTC) is an example of presentation layer.
A database link created by one user for exclusive use.
See also database link and public database link.
A collection of parameters that specifies preferences for enabling and configuring Oracle Net Services features on the client or server. A profile is stored and implemented through the sqlnet.ora file.
An address that identifies the network address of a network object.
When a connection is made, the client and the receiver of the request, such as the listener or Oracle Connection Manager, are configured with identical protocol addresses. The client uses this address to send the connection request to a particular network object location, and the recipient listens for requests on this address. It is important to install the same protocols for the client and the connection recipient, as well as configure the same addresses.
A feature of Oracle Connection Manager that enables a client and server with different networking protocols to communicate with each other. This feature replaces functionality previously provided by the Oracle Multi-Protocol Interchange with SQL*Net version 2.
Designates a particular presentation layer and session layer combination.
A server that substitutes for a real server, forwarding client connection requests to the real server or to other proxy servers. Proxy servers provide access control, data and system security, monitoring, and caching.
A database link created by a DBA on a local database that is accessible to all users on that database.
See also database link and private database link.
An Oracle Context contained in each identity management realm. It stores the following information:
-
User naming policy of the identity management realm, that is, how users are named and located
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Mandatory authentication attributes
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Location of groups in the identity management realm
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Privilege assignments for the identity management realm, for example, who has privileges to add more users to the realm.
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Application specific data for that realm including authorizations
● relative distinguished name (RDN)
A fully-qualified X.500 name. It is the local, most granular level entry name. In the example, cn=sales,dc=us,dc=acme,dc=com, the RDN is cn=sales.
In the Oracle Identity Management infrastructure, the root Oracle Context is an entry in Oracle Database Net Services Reference containing a pointer to the default identity management realm in the infrastructure. It also contains information about how to locate an identity management realm given the simple name of the realm.
An industry-standard protocol designed by Netscape Communications Corporation for securing network connections. SSL provides authentication, encryption, and data integrity using public key infrastructure (PKI).
A program that responds to requests from various clients or performs some operation. For example, the database is a service that stores and retrieves data for clients.
A process that acts a connection point from the listener to the database server. A service handler can be a dispatcher or dedicated server.
A logical representation of a database, which is the way a database is presented to clients. A database can be presented as multiple services and a service can be implemented as multiple database instances. The service name is a string that is the global database name, that is, a name comprising the database name and domain name, entered during installation or database creation. If you are not sure what the global database name is, then you can obtain it from the value of the SERVICE_NAMES parameter in the initialization parameter file.
The service name is included in the connect data part of the connect descriptor.
A feature by which the PMON process automatically registers information with a listener. Because this information is registered with the listener, the listener.ora file does not need to be configured with this static information.
Service registration provides the listener with information about:
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Service names for each running instance of the database
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Instance names of the database
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Service handlers (dispatcher or dedicated server) available for each instance
These enable the listener to direct a client request appropriately.
-
Dispatcher, instance, and node load information
This load information enables the listener to determine which dispatcher can best handle a client connection request. If all dispatchers are blocked, then the listener can spawn a dedicated server for the connection.
A buffer that Oracle Net uses to place data before transmitting it across the network. Oracle Net sends the data in the buffer either when requested or when it is full.
A network layer that provides the services needed by the protocol address entities that enable them to organize and synchronize their dialog and manage their data exchange. This layer establishes, manages, and terminates network sessions between the client and server. An example of a session layer is Network Session (NS).
Combining multiple sessions for transmission over a single network connection to conserve the operating system's resources.
A database server that is configured to allow many user processes to share very few server processes, so the number of users that can be supported is increased. With shared server configuration, many user processes connect to a dispatcher. The dispatcher directs multiple incoming network session requests to a common queue. An idle shared server process from a shared pool of server processes picks up a request from the queue. This means that a small pool of server processes can serve a large number of clients. Contrast with dedicated server.
A process type used with shared server configuration.
A section of the listener.ora file that defines the Oracle System Identifier (SID) of the database served by the listener. This section is valid only for Oracle databases release 8.0, as information for Oracle8i or later instances is automatically registered with the listener. Static configuration is also required for other services, such as external procedure calls and Heterogeneous Services.
The ability for a user to log in to different servers using a single password. This permits the user to authenticate to all servers the user is authorized to access.
A configuration file for the client or server that specifies:
-
Client domain to append to unqualified service names or net service names
-
Order of naming methods the client should use when resolving a name
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Logging and tracing features to use
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Route of connections
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External naming parameters
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Oracle Advanced Security parameters
The sqlnet.ora file typically resides in the ORACLE_HOME/network/admin directory.
A group of shared memory structures that contain data and control information for an Oracle instance.
Transmission Control Protocol/Internet Protocol. The standard communication protocol used for client/server conversation over a network.
A protocol that enables an Oracle application on a client to communicate with remote Oracle databases through the TCP/IP and Secure Sockets Layer (SSL).
The amount of time it takes for a message to be sent and processed from the client to the server or from the server to the client
A configuration file that maps net service names to connect descriptors. This file is used for the local naming method. The tnsnames.ora file typically resides in the ORACLE_HOME/network/admin directory.
A facility that writes detailed information about an operation to an output file. The trace facility produces a detailed sequence of statements that describe the events of an operation as they are run. Administrators use the trace facility for diagnosing an abnormal condition. It is not normally turned on.
See also logging.
● Transparent Application Failover (TAF)
A run-time failover for high-availability environments, such as Oracle Real Application Clusters and Oracle Fail Safe, that refers to the failover and re-establishment of application-to-service connections. It enables client applications to automatically reconnect to the database if the connection fails, and, optionally, resume a SELECT statement that was in progress. This reconnect happens automatically from within the Oracle Call Interface (OCI) library.
● Transparent Network Substrate (TNS)
A foundation technology, built into the Oracle Net foundation layer that works with any standard network transport protocol.
A networking layer that maintains end-to-end reliability through data flow control and error recovery methods. The Oracle Net foundation layer uses Oracle protocol support for the transport layer.
A presentation layer type that is used in a typical Oracle Net connection to provide character set and data type conversion between different character sets or formats on the client and server.
A piece of shared memory used by the dispatcher for client database connection requests and replies. The dispatcher places a virtual circuit on a common queue when a request arrives. An idle shared server picks up the virtual circuit from the common queue, services the request, and relinquishes the virtual circuit before attempting to retrieve another virtual circuit from the common queue.
World Wide Web Distributed Authoring and Versioning. A protocol with a set of extensions to HTTP which allows users to manage files on remote Web servers.
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GlossaryGlossary
A Large Object datatype that is a binary file residing in the file system, outside of the database data files and tablespace. Note that the BFILE datatype is also referred to as an external LOB in some documentation.
A Large Object datatype that has content consisting of binary data and is typically used to hold unstructured data. The BLOB datatype is included in the category Persistent LOBs because it resides in the database.
● Character Large Object (CLOB)
The LOB datatype that has content consisting of character data in the database character set. A CLOB can be indexed and searched by the Oracle Text search engine.
Deduplication enables Oracle Database to automatically detect duplicate LOB data and conserve space by only storing one copy (if storage parameter is SECUREFILE).
A Large Object datatype that is stored outside of the database tablespace. The BFILE datatype is the only external LOB datatype. See also BFILE.
A large object (LOB) that is stored in the database in a BLOB/CLOB/NCLOB column.
Large Objects include the following SQL datatypes: BLOB, CLOB, NCLOB, and BFILE. These datatypes are designed for storing data that is large in size. See also BFILE, Binary Large Object, Character Large Object, and National Character Large Object.
A large object datatype that is a field of an object datatype. For example a CLOB field of an object type.
The actual data stored by the Large Object. For example, if a BLOB stores a picture, then the value of the BLOB is the data that makes up the image.
● National Character Large Object
The LOB datatype that has content consisting of Unicode character data in the database national character set. An NCLOB can be indexed and searched by the Oracle Text search engine.
A BLOB, CLOB, or NCLOB that is stored in the database. A persistent LOB instance can be selected out of a table and used within the scope of your application. The ACID (atomic, consistent, isolated, durable) properties of the instance are maintained just as for any other column type. Persistent LOBs are sometimes also referred to as internal persistent LOBs or just, internal LOBs.
A persistent LOB can exist as a field of an object datatype and an instance in a LOB-type column. For example a CLOB attribute of an instance of type object.
See also temporary LOB and external LOB.
LOB storage parameter that allows deduplication, encryption, and compression. The opposite parameter, that does not allow these features, is BASICFILE.
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GlossaryGlossary
● Oracle Automatic Storage Management disk group
A set of disk devices that Oracle Automatic Storage Management manages as a single unit. Each disk device can be an individual physical disk, a multiple disk device such as a RAID storage array or logical volume, or even a partition on a physical disk. You can create the Oracle Automatic Storage Management disk group when you create the Oracle Automatic Storage Management instance, or with Oracle Database Configuration Assistant.
● Oracle Automatic Storage Management instance
The Oracle instance that manages Oracle Automatic Storage Management disk groups Oracle Automatic Storage Management disk groups. It is created automatically when you install and configure Oracle Automatic Storage Management. See also Oracle system identifier (SID).
● Oracle Automatic Storage Management
Enables creation of a single disk group from a collection of individual disk devices. It balances I/O to the disk group across all of the devices in the disk group. It also implements striping and mirroring to improve I/O performance and data reliability.
● automatic undo management mode
A mode of Oracle Database in which undo data is stored in a dedicated undo tablespace. Unlike in manual undo management mode, the only undo management that you must perform is the creation of the undo tablespace. All other undo management is performed automatically.
A specially formatted description of the destination for a network connection. A connect descriptor contains destination service and network route information.
The destination service is indicated by using its service name for the Oracle Database or its Oracle system identifier (SID) for Oracle release 11.2 databases. The network route provides, at a minimum, the location of the listener through use of a network address.
A name, net service name, or service name that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a connect identifier in a connect string for the service to which they want to connect, for example:
SQL> CONNECT user_name@connect_identifier Enter password: password
Files that record the physical structure of a database and contain the database name, the names and locations of associate datafiles and online undo tablespace, the time stamp of the database creation, the current log sequence number, and checkpoint information.
The network domain within which most client requests take place. It can be the domain where the client resides, or a domain from which the client often requests network services. The default domain is also the client configuration parameter that determines what domain to append to unqualified network name requests. A name request is unqualified if it does not have a "." character within it.
A naming method that specifies a directory server to resolve a net service name into a connect descriptor. The net service name is stored centrally in a directory server.
A Lightweight Directory Access Protocol (LDAP)-compliant directory server. A directory can provide centralized storage and retrieval of database network components, user and corporate policies preferences, user authentication, and security information, replacing client-side and server-side localized files.
Procedure or function written in the C programming language and stored in a shared library. An Oracle server can call external procedures or functions using PL/SQL routines. For Oracle Database to connect to external procedures, the server must be configured with a net service name and the listener must be configured with protocol address and service information.
The full database name that uniquely distinguishes it from any other database in your network domain.
For example:
sales.us.example.com
where sales is the name you want to call your database and us.example.com is the network domain in which the database is located.
● initialization parameter file
An ASCII text file that contains information needed to initialize a database and instance.
Process associated with a running Oracle Database instance. When a database is started on a database server (regardless of the type of computer), Oracle Database allocates a memory area called the System Global Area and starts one or more Oracle Database processes. This combination of the System Global Area and Oracle Database processes is called an instance. The memory and processes of an instance manage the associated database's data efficiently and serve the users of the database.
A predefined component set that automatically selects which components to install. See "Oracle Database Editions" for a list of installation types available with each top-level component.
● Interprocess Communication (IPC)
A protocol that client applications use that resides on the same node as the listener to communicate with the database. IPC can provide a faster local connection than TCP/IP.
A process that resides on the server and whose responsibility is to listen for incoming client connection requests and manage the traffic to the server.
When a client requests a network session with a database server, a listener receives the actual request. If the client information matches the listener information, then the listener grants a connection to the database server.
A configuration file for the listener that identifies the:
-
Listener name
-
Protocol addresses on which it is accepting connection requests
-
Services for which it is listening
The listener.ora file resides in the ORACLE_HOME\network\admin directory.
An Oracle Database 11g Release 2 (11.2) does not require identification of the database service because of service registration. However, static service configuration is required for an Oracle Database 11g Release 2 (11.2) if you plan to use Oracle Enterprise Manager.
A naming method that resolves a net service name into a connect descriptor. This name is configured and stored in the tnsnames.ora file on each individual client.
A mode of the database in which undo blocks are stored in user-managed rollback segments.
A resolution method used by a client application to resolve a connect identifier to a network address when attempting to connect to a database service. Oracle Net Services supports the following naming methods:
-
Local naming
-
Directory naming
-
Host naming
-
External naming
A simple name for a service that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a net service name in a connect string for the service to which they want to connect:
SQL> CONNECT user_name Enter password: password SQL> @net_service_name
Depending on your needs, net service names can be stored in a variety of places, including:
-
Local configuration file, tnsnames.ora, on each client
-
Directory server
-
External naming service, such as Network Information Service (NIS) or Cell Directory Service (CDS)
Acronym for operating system specific. The initialization file parameter OS_AUTHENT_PREFIX enables users to specify a prefix that Oracle uses to authenticate users attempting to connect to the database. Oracle concatenates the value of this parameter to the beginning of the user's operating system account name. When a connection request is attempted, Oracle compares the prefixed user name with Oracle user names in the database.
The default value of this parameter is "" (a null string), thereby eliminating the addition of any prefix to operating system account names. In earlier releases, OPS$ was the default setting.
ORACLE_BASE is the root of the Oracle Database directory tree. The Oracle Base directory is the top level directory that you can use to install the various oracle software products. You can use the same Oracle base directory for multiple installations. If you install an OFA-compliant database using Oracle Universal Installer defaults, then ORACLE_BASE is X:\oracle\product\11.2.0 where X is any hard drive (for example, C:\oracle\product\11.2.0).
Corresponds to the environment in which Oracle Database products run. This environment includes location of installed product files, PATH variable pointing to products' binary files, registry entries, net service name, and program groups.
If you install an OFA-compliant database, using Oracle Universal Installer defaults, Oracle home (known as \ORACLE_HOME in this guide) is located beneath X:\ORACLE_BASE. The default Oracle home is db_n where n is the Oracle home number. It contains subdirectories for Oracle Database software executables and network files. See also Oracle home.
The directory path to install Oracle components (for example, C:\app\oracle\product\11.2.0\dbhome_n). You are prompted to enter an Oracle home in the Path field of the Specify File Locations window. See also ORACLE_HOME.
A set of rules that determine what can be stored in an LDAP-compliant directory server. Oracle has its own schema that is applied to many types of Oracle entries, including Oracle Net Services entries. The Oracle schema for Oracle Net Services entries includes the attributes the entries may contain.
A networking communication layer that establishes and maintains the connection between the client application and server, as well as exchanging messages between them.
An address that identifies the network address of a network object.
When a connection is made, the client and the receiver of the request, such as the listener, or Oracle Connection Manager, are configured with identical protocol addresses. The client uses this address to send the connection request to a particular network object location, and the recipient "listens" for requests on this address. It is important to install the same protocols for the client and the connection recipient, and to configure the same addresses.
Portions of a physical disk that are accessed at the lowest possible disk (block) level.
Files that contain a record of all changes made to data in the database buffer cache. If an instance failure occurs, then an administrator can use the redo log files to recover the modified data that was in memory.
A set of tables located in any Oracle database accessible to the Oracle Management Server. Oracle Management Server uses a repository to store all system data and application data, information about the state of managed nodes distributed throughout the environment, as well as information about the separately licensable management packs.
A feature by which the PMON process (an instance background process) automatically registers information with a listener. Because this information is registered with the listener, the listener.ora file must not be configured with this static information.
Service registration provides the listener with the following information:
-
Service names for each running instance of the database
-
Instance names of the database
-
Service handlers (dispatchers and dedicated servers) available for each instance
This allows the listener to direct a client's request appropriately.
-
Dispatcher, instance, and node load information
This allows the listener to determine which dispatcher can best handle a client connection's request. If all dispatchers are blocked, the listener can spawn a dedicated server for the connection.
This information allows the listener to determine how best to service a client connection request.
The Oracle system identifier that distinguishes the database from all other databases on your computer. The SID automatically defaults to the database name portion of the global database name (sales in the example sales.us.example.com) until you reach eight characters or enter a period. You can accept or change the default value.
The SID can also see an Oracle Automatic Storage Management instance SID, available when you install Oracle Automatic Storage Management.
A configuration file for the client or server that specifies the:
-
Client domain to append to unqualified service names or net service names
-
Order of naming methods for the client to use when resolving a name
-
Logging and tracing features to use
-
Route of connections
-
External naming parameters
-
Oracle Advanced Security parameters
The sqlnet.ora file resides in ORACLE_HOME\network\admin.
An industry standard protocol designed by Netscape Communications Corporation for securing network connections. SSL provides authentication, encryption, and data integrity using public key infrastructure (PKI).
A group of shared memory structures that contain data and control information for an Oracle Database instance.
See SID.
A logical storage unit within a database. Tablespaces are divided into logical units of storage called segments, which are further divided into extents.
A configuration file that contains net service names mapped to connect descriptors. This file is used for the local naming method. The tnsnames.ora file resides in ORACLE_HOME\network\admin.
An tablespace that contains one or more undo segments. The creation of any other types of segment (for example, tables, indexes) in undo tablespaces is not allowed.
In the automatic mode, each Oracle instance is assigned one and only one undo tablespace. Each undo tablespace is composed of a set of undo files. Undo blocks are grouped in extents. At any point in time, an extent is either allocated to (and used by) a transaction table, or is free.
Blocks in undo tablespaces are grouped into the following categories:
-
File control blocks, bitmap blocks, and so forth used for space management
-
Undo segments containing transaction table blocks, undo blocks, and extent-map blocks used for transaction management
-
Free blocks that are unallocated to file control or undo segments
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Glossary| Oracle? Database Installation Guide 11g Release 2 (11.2) for IBM AIX on POWER Systems (64-Bit) E48740-01 |
Glossary
● Oracle Automatic Storage Management disk group
A set of disk devices that Oracle Automatic Storage Management (Oracle ASM) manages as a unit. Each disk device can be an individual physical disk, a multiple disk device such as a RAID storage array or logical volume, or even a partition on a physical disk. You can create the Oracle ASM disk group when you create the Oracle Automatic Storage Management instance, or with Oracle Database Configuration Assistant.
● Oracle Automatic Storage Management instance
The Oracle instance that manages an Oracle Automatic Storage Management disk group. It is created automatically when you install and configure Oracle Automatic Storage Management. See also Oracle system identifier (SID).
● Oracle Automatic Storage Management
Enables creation of a single disk group from a collection of individual disk devices. It balances I/O to the disk group across all of the devices in the disk group. It also implements striping and mirroring to improve I/O performance and data reliability.
● automatic undo management mode
A mode of Oracle Database in which undo data is stored in a dedicated undo tablespace. Unlike in manual undo management mode, the only undo management that you must perform is the creation of the undo tablespace. All other undo management is performed automatically.
A specially formatted description of the destination for a network connection. A connect descriptor contains destination service and network route information.
The destination service is indicated by using its service name for the Oracle Database or its Oracle system identifier (SID) for Oracle release 11.2 databases. The network route provides, at a minimum, the location of the listener through use of a network address.
A name, net service name, or service name that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a connect identifier in a connect string for the service to which they want to connect, for example:
SQL> CONNECT user_name@connect_identifier Enter password: password
Files that record the physical structure of a database and contain the database name, the names and locations of associated datafiles and online undo tablespace, the time stamp of the database creation, the current log sequence number, and checkpoint information.
The network domain within which most client requests take place. It can be the domain where the client resides, or a domain from which the client often requests network services. The default domain is also the client configuration parameter that determines what domain to append to unqualified network name requests. A name request is unqualified if it does not have a "." character within it.
A naming method that specifies a directory server to resolve a net service name into a connect descriptor. The net service name is stored centrally in a directory server.
A Lightweight Directory Access Protocol (LDAP)-compliant directory server. A directory can provide centralized storage and retrieval of database network components, user and corporate policies preferences, user authentication, and security information, replacing client-side and server-side localized files.
Procedure or function written in the C programming language and stored in a shared library. An Oracle server can call external procedures or functions using PL/SQL routines. For Oracle Database to connect to external procedures, the server must be configured with a net service name and the listener must be configured with protocol address and service information.
The full database name that uniquely distinguishes it from any other database in your network domain.
For example:
sales.us.example.com
where sales is the name you want to call your database and us.example.com is the network domain in which the database is located.
● initialization parameter file
An ASCII text file that contains information needed to initialize a database and instance.
Process associated with a running Oracle Database instance. When a database is started on a database server (regardless of the type of computer), Oracle Database allocates a memory area called the System Global Area and starts one or more Oracle Database processes. This combination of the System Global Area and Oracle Database processes is called an instance. The memory and processes of an instance manage the associated database's data efficiently and serve the users of the database.
A predefined component set that automatically selects which components to install. See "Oracle Database Editions" for a list of installation types available with each top-level component.
● Interprocess Communication (IPC)
A protocol that client applications use that resides on the same node as the listener to communicate with the database. IPC can provide a faster local connection than TCP/IP.
A process that resides on the server and whose responsibility is to listen for incoming client connection requests and manage the traffic to the server.
When a client requests a network session with a database server, a listener receives the actual request. If the client information matches the listener information, then the listener grants a connection to the database server.
A configuration file for the listener that identifies the:
-
Listener name
-
Protocol addresses on which it is accepting connection requests
-
Services for which it is listening
The listener.ora file resides in the $ORACLE_HOME/network/admin directory.
An Oracle Database 11g Release 2 (11.2) does not require identification of the database service because of service registration. However, static service configuration is required for an Oracle Database 11g Release 2 (11.2) if you plan to use Oracle Enterprise Manager.
A naming method that resolves a net service name into a connect descriptor. This name is configured and stored in the tnsnames.ora file on each individual client.
A mode of the database in which undo blocks are stored in user-managed rollback segments.
A resolution method used by a client application to resolve a connect identifier to a network address when attempting to connect to a database service. Oracle Net Services supports the following naming methods:
-
Local naming
-
Directory naming
-
Host naming
-
External naming
A simple name for a service that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a net service name in a connect string for the service to which they want to connect:
SQL> CONNECT user_name@net_service_name Enter password: password
Depending on your needs, net service names can be stored in a variety of places, including:
-
Local configuration file, tnsnames.ora, on each client
-
Directory server
-
External naming service, such as Network Information Service (NIS) or Cell Directory Service (CDS)
Acronym for operating system specific. The initialization file parameter OS_AUTHENT_PREFIX enables users to specify a prefix that Oracle uses to authenticate users attempting to connect to the database. Oracle concatenates the value of this parameter to the beginning of the user's operating system account name. When a connection request is attempted, Oracle compares the prefixed user name with Oracle user names in the database.
The default value of this parameter is "" (a null string), thereby eliminating the addition of any prefix to operating system account names. In earlier releases, OPS$ was the default setting.
ORACLE_BASE is the root of the Oracle Database directory tree. The Oracle Base directory is the top level directory that you can use to install the various oracle software products. You can use the same Oracle base directory for multiple installations. For example, /u01/app/oracle is an Oracle base directory created by the oracle user.
Corresponds to the environment in which Oracle Database products run. If you install an OFA-compliant database, using Oracle Universal Installer defaults, Oracle home (known as $ORACLE_HOME in this guide) is located beneath $ORACLE_BASE. The default Oracle home is db_n where n is the Oracle home number. It contains subdirectories for Oracle Database software executables and network files. See also Oracle home.
The directory path to install Oracle components (for example, /u01/app/oracle/product/11.2.0/db_n). You are prompted to enter an Oracle home in the Path field of the Specify File Locations window. See also ORACLE_HOME.
A set of rules that determine what can be stored in an LDAP-compliant directory server. Oracle has its own schema that is applied to many types of Oracle entries, including Oracle Net Services entries. The Oracle schema for Oracle Net Services entries includes the attributes the entries may contain.
A networking communication layer that establishes and maintains the connection between the client application and server, and also exchanging messages between them.
An address that identifies the network address of a network object.
When a connection is made, the client and the receiver of the request, such as the listener, or Oracle Connection Manager, are configured with identical protocol addresses. The client uses this address to send the connection request to a particular network object location, and the recipient "listens" for requests on this address. It is important to install the same protocols for the client and the connection recipient, and to configure the same addresses.
Portions of a physical disk that are accessed at the lowest possible disk (block) level.
Files that contain a record of all changes made to data in the database buffer cache. If an instance failure occurs, then an administrator can use the redo log files to recover the modified data that was in memory.
A set of tables located in any Oracle database accessible to the Oracle Management Server. Oracle Management Server uses a repository to store all system data and application data, information about the state of managed nodes distributed throughout the environment, and information about the separately licensable management packs.
A feature by which the PMON process (an instance background process) automatically registers information with a listener. Because this information is registered with the listener, the listener.ora file does not have to be configured with this static information.
Service registration provides the listener with the following information:
-
Service names for each running instance of the database
-
Instance names of the database
-
Service handlers (dispatchers and dedicated servers) available for each instance to enable the listener to direct a client's request appropriately.
-
Dispatcher, instance, and node load information
To enable the listener to determine which dispatcher can best handle a client connection's request. If all dispatchers are blocked, the listener can spawn a dedicated server for the connection.
This information enables the listener to determine how best to service a client connection request.
The Oracle system identifier that distinguishes the database from all other databases on your computer. The SID automatically defaults to the database name portion of the global database name (sales in the example sales.us.example.com) until you reach eight characters or enter a period. You can accept or change the default value.
The SID can also refer to an Oracle ASM instance SID, available when you install Oracle Automatic Storage Management.
A configuration file for the client or server that specifies the:
-
Client domain to append to unqualified service names or net service names
-
Order of naming methods for the client to use when resolving a name
-
Logging and tracing features to use
-
Route of connections
-
External naming parameters
-
Oracle Advanced Security parameters
The sqlnet.ora file resides in $ORACLE_HOME/network/admin.
An industry standard protocol designed by Netscape Communications Corporation for securing network connections. SSL provides authentication, encryption, and data integrity using public key infrastructure (PKI).
A group of shared memory structures that contain data and control information for an Oracle Database instance.
See SID.
A logical storage unit within a database. Tablespaces are divided into logical units of storage called segments, which are further divided into extents.
A configuration file that contains net service names mapped to connect descriptors. This file is used for the local naming method. The tnsnames.ora file resides in $ORACLE_BASE/network/admin.
A tablespace that contains one or more undo segments. The creation of any other types of segment (for example, tables, indexes) in undo tablespaces is not allowed.
In the automatic mode, each Oracle instance is assigned one and only one undo tablespace. Each undo tablespace is composed of a set of undo files. Undo blocks are grouped in extents. At any point in time, an extent is either allocated to (and used by) a transaction table, or is free.
Blocks in undo tablespaces are grouped into the following categories:
-
File control blocks, bitmap blocks, and so forth used for space management
-
Undo segments containing transaction table blocks, undo blocks, and extent-map blocks used for transaction management
-
Free blocks that are unallocated to file control or undo segments
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GlossaryGlossary
A database session parameter that is set by an application to identify the action associated with a database request.
The word 'affinity' is used to describe any strategy that is expected to increase the probability that a work request finds the required data cached in the instance to which the work request is routed.
Aggregation is the process of taking a collection of measurements, and combining them to produce an aggregate measure. For example, counting all the work requests that are completed by a given server in a given Performance Class is a form of aggregation. Totaling the CPU time used by all the work requests in a given Performance Class handled by a particular server during a time interval is another form of aggregation.
An application is software that runs on a system and provides one or more services to a user or a group of users. Oracle CollabSuite, Oracle Email, Oracle CRM, and Oracle Financials are all examples of applications. CollabSuite is an example of an application that provides multiple services.
An application usually consists of multiple components; there may be a database component, a J2EE component, a client PC component, a batch component, a web component, a Web Services component, and so on.
Automatic Provisioning attempts to automate, as much as possible, the activities involved in re-tasking a piece of hardware. For example, taking a piece of hardware that has been running with one operating system and one set of application components, and re-deploying the hardware with a different operating system and a different set of application components.
The average of the response times for all work requests for a Performance Class for a given time period, specified in seconds.
A component or resource that limits the performance of an application or an entire system.
Capacity planning is the act of determining the amount and type of hardware needed to service projected peak user loads. Capacity planning is often done as part of a larger capital equipment budgeting cycle, and usually involves making load projections months into the future.
Value matching rules that are applied to attributes of the work request to map work requests to Performance Classes.
The amount of work performed in a system in which a fixed number of users interact with the application and each of these users issues a succession of requests. A new request from a user is triggered only after the completion of a previous request by the same user. A user submits a request, waits for the response of that request, thinks for a certain time and then sends a new request. The average time elapsed between the response from a previous request and the submission of a new request by the same user is called the "think time".
A closed workload is also referred to as a session-based workload.
Any software that enables groups, or clusters, of connected computers to operate or be controlled as a unit.
Conditioned data is created from raw data in a post-processing step of some kind. Taking averages, removing outliers, filtering, and parameter estimation procedures are all examples of the kind of post-processing that may be used to create conditioned data from raw data.
A database service is a user-created service that is managed by Oracle Clusterware and serves as a database session connection point. A database service may be offered on one or more Oracle RAC instances, and managed on a for-instance basis (for starting and stopping the service).
Demand is a measure of the amount of work being presented to the system and is usually measured in work requests or requests per second.
An elapsed time measurement (also known as a wall clock time measurement) is a measurement of a single, contiguous time interval. The elapsed time interval begins at some time t1 and ends at another time t2, where both times are read from the same clock. The elapsed time measurement is the value of (t2 - t1).
The expression end-to-end response time includes all time spent and all work done from the time a user request is received (for example, from clicking the Submit button in a browser), until the response is sent back to the user in its entirety. End-to-end response time includes time spent in application servers, Oracle Database, Oracle Automatic Storage Management, and traversing the internal networks of the data center.
The entry point is the initial point of contact between a work request and the Oracle Database QoS Management system. Work requests are initially classified and tagged at their entry point.
Fair share scheduling attempts to fairly allocate a resource such as a CPU among a collection of users, ensuring that each user gets a specified share of the available resource. Lottery based scheduling is one kind of fair share scheduling.
When a Performance Class is meeting its Performance Objectives, headroom refers to the difference between the actual response times and the required response times, or the surplus in performance.
Layer Active Time is the cumulative time that a work request is actively doing work at a layer, excluding time spent waiting on layers below. Layer Active Time includes time spent executing at the layer, and time spent waiting for layer local resources, such as the CPU, locally connected disks, memory, and so on.
Layer Response Time is the elapsed time for a work request to be completely handled by a specific layer. The layer response time includes the time spent executing the work request, and the time spent waiting for local and remote resources and servers.
Often, a single work request from an end user (for example, clicking a link in a browser) causes several requests to arrive at various layers of the system. Each time a request is handled by a layer is called a layer visit.
Load shedding refers to the act of rejecting some work requests, so that other work requests may complete successfully. Rejecting requests gracefully may require modifications to your applications. For example, you might want the end user to see a customized rejection page. Alternatively, you might want to store information from the work request so you can reply to the requester at a later time.
Lottery based scheduling is a scheduling algorithm that uses random numbers to apportion resources (such as a CPU) among a collection of users, according to a pre-set distribution.
A contiguous time interval during which automated maintenance tasks are run. Maintenance windows are Oracle Scheduler windows that belong to the window group named MAINTENANCE_WINDOW_GROUP.
A state indicating that there is a limited amount of available memory on a server.
Module is the database session parameter that is set by an application, generally to identify the application module making the database request.
Work performed in a system in which new work requests to an application come from outside the system being managed. The work requests are independent of each other and the work request arrival rate is not influenced by the response time for previous requests, or the number of requests that have already arrived and are being processed. The number of work requests the system may be asked to execute at any given time can range from zero to infinity. The system's resources or servers perform various activities to process a work request and the work request leaves the system when processing is complete.
Open workloads are also referred to as request-based workloads.
● Oracle Grid Infrastructure for a cluster
A term assigned to the software stack comprising Oracle's generic Clusterware, Oracle Automatic Storage Management (Oracle ASM), Oracle RAC agents, and the Oracle RAC database management infrastructure layer.
● Oracle Database Resource Manager
Oracle Database Resource Manager is a software component available with the Oracle Database; Oracle Database Resource Manager enables an administrator to establish Resource Plans that control how various resources (such as the CPU) may be allocated to consumer groups, which are collections of work requests. The intent is very similar to Oracle Database QoS Management's Performance Class.
Oracle Database QoS Management attempts to identify performance bottlenecks due to Performance Classes waiting too long for required resources, such as CPU, Global Cache, or I/O.
A Performance Class is a group of related work requests. Performance Objectives are written for a Performance Class. All work requests that are grouped into a particular Performance Class have the same performance objective.
The Performance Class rank represents the business criticalness of each Performance Class in a set of Performance Objectives that are in effect at a given time. When there are not enough resources available to service all applicable Performance Classes at the same time, Oracle Database QoS Management works to meet the Performance Objectives for the Performance Classes that are highest ranked at the expense of Performance Classes with a lesser rank. For example, Performance Classes with an rank of Lowest are sacrificed if necessary to ensure that Performance Classes of higher rank (Highest, High, Medium and Low) continue to meet their Performance Objectives.
Performance objectives refers to business level objectives for the system. A performance objective includes both Performance Objectives and availability objectives.
A Performance Objective defines a level of performance that is optimal for business purposes for a given Performance Class. For a particular Performance Class, a Performance Objective specify the target average response time for that workload.
In high load situations, work of lower business criticalness may be deliberately starved for resources by the Oracle Database QoS Management system so that more important work can meet its Performance Objectives; in this circumstance the user might receive a "Server Busy" message instead of just experiencing very poor response times.
A Performance Policy is a collection of Performance Objectives and Performance Class ranks that are intended to be in force at the same time. A Performance Policy must include at least one Performance Objective and Performance Class rank for each Performance Class, unless the Performance Class is marked Measure-Only. A Performance Policy optionally includes server pool directive overrides to set a baseline configuration of server resources for the time period in which the policy is active.
● Performance Satisfaction Metric
A normalized numeric value that indicates how well a particular Performance Objective is being met, and which enables Oracle Database QoS Management to compare the performance of the system for widely differing Performance Objectives.
A Policy Set is a wizard-generated XML document that governs the operation of Oracle Database QoS Management. A Policy Set specifies server pools and their hosted Performance Classes, the collection of Performance Policies that specify the Performance Objectives for each Performance Class, and the server pool directive overrides for each Performance Policy.
Program name is a database session attribute set by an application that is generally used to identify the program making the database request.
Raw data is data that has not been post-processed in any way. Counts, totals, and individual sample values are examples of raw data.
A resource is a shared item that has limited quantity that is required to process a request. For example, CPU Time, threads, memory, I/O devices, slots in queues, network bandwidth, and temp space are all resources. Servers typically provide resources.
A resource allocation control (also informally known as a knob) is a parameter, or collection of parameters, to a resource allocation mechanism. Examples of a resource allocation control include:
-
A Consumer Group for Oracle Database Resource Manager
-
The number of servers in a server pool
● resource allocation mechanism
A resource allocation mechanism is something that gives an external entity such as a person or Oracle Database QoS Management the ability to control how some collection of resources are allocated. Oracle Database Resource Manager is an example of a Resource Allocation Mechanism.
A resource metric is a metric that can be measured for any resource. Examples include Resource Usage Time and Resource Wait Time.
Resource usage time is the cumulative time that a work request had exclusive use of a resource.
Resource use is a measurement that accumulates a specified set of elapsed time measurements into a single number. For example, a measurement of the CPU time spent on a given work request on a given server is a resource measurement: the specified work request uses the CPU for many separate intervals of time as the work request is processed.
Resource wait time is the cumulative time spent waiting for a resource by a work request that is ready to use that resource.
The time between the server receiving a transaction request and sending out a response after committing or aborting the transaction.
A work request that uses significantly more resources than expected; for example, the work request may be in a non-terminating loop. In some systems, facilities are provided to stop or re-prioritize rogue work.
Routing is the act of choosing the path that a work request takes through the system. This includes all choices made when picking an entity in another tier of the system to which to pass a work request.
A server is a shared computer, typically not dedicated to a single user. A server can be as simple as a single CPU blade, or as complex as a large server with many CPUs sharing memory.
A server pool is a collection of servers created by the CRS Administrator using either Enterprise Manager Database Control or the Server Control (SRVCTL) utility. Server pools are contained within tiers; each service is assigned to run in a specific server pool.
A number from 0 to 1000 (0 being least important) that ranks a server pool among all other server pools in a cluster.
● server pool directive overrides
High availability guidelines for the cluster administrator server to keep the cluster highly available.
A service provides a well-recognized value to a user (client) or group of users. A service is provided to an application, and runs on a system. For example, CollabSuite provides a set of services such as Files, Calendar, Web Conferences, and so on. See also database services.
Operational management decisions, such as the hours of operation, capacity planning, provisioning, placement, and so on, are made on a service-by-service basis.
A shared collection of servers and their associated infrastructure (networks, firewalls, storage systems, and so on) over which a workload management instance operates.
System metrics are metrics that help us to connect the things that are happening at the different layers. They provide a framework within which the rest of the analysis can be done. Examples include request counts, Layer Response Time, Layer Active Time, and so on.
All tiers of the system must provide the same set of system metrics.
When a work request is received by the system, an attempt is made to classify the type of work requested. The objective of classification is to determine which Performance Objective applies to this particular work request. The result of classification is a tag (the Performance Class name) that is carried with the work request as it proceeds through the system. The tag enables the work request to be associated with the Performance Objective for the workload (Performance Class).
A tier is a logical processing component within a system. The tiers are stacked on top of each other to provide the end-to-end processing stack for a system. WebCache, OHS, OC4J, Oracle Database and Oracle Automatic Storage Management are examples of tiers.
There may be multiple entities in a given tier providing either redundancy or distinct functionality. For example, a system might include two OHS instances for higher availability and two databases, one for CRM, and the other for ERP.
The OCI_ATTR_USERNAME or the Oracle Database user that is used to authenticate to the database.
A work request is the smallest atom of work that a user can initiate. A work request can be an HTTP request, a SOAP request, a SQL statement sent to the database, or the execution of a process. A work request arrives at a layer, perhaps from the outside world, perhaps from another layer. The work request is processed, and a response is generated; the response is sent back to the requester.
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GlossaryGlossary
A specially formatted description of the destination for a network connection. A connect descriptor contains destination service and network route information.
The destination service is indicated by using its service name for the Oracle Database or its Oracle system identifier (SID) for Oracle release 8.0, or version 7 databases. The network route provides, at a minimum, the location of the listener through use of a network address.
The network domain within which most client requests take place. It can be the domain where the client resides, or a domain from which the client often requests network services. The default domain is also the client configuration parameter that determines what domain to append to unqualified network name requests. A name request is unqualified if it does not have a "." character within it.
A Naming method that allows clients to connect to a database server without any configuration. Clients use a simple TCP/IP address, which consists of a host name and optional port number, service name, and instance name:
SQL>CONNECT user_name@host[:port][/service_name][/instance_name] Enter password: password
An installation type is a predefined component set that automatically selects which components to install. See "Oracle Database Client Installation Types" for a list of installation types available with each top-level component.
● Interprocess Communication (IPC)
A protocol used by client applications that resides on the same node as the listener to communicate with the database. IPC can provide a faster local connection than TCP/IP.
A file created by the Oracle Net Configuration Assistant that contains the following directory access information:
-
Type of directory
-
Location of directory
-
Default administrative context the client or server uses to look up or configure connect identifiers for connections to database services
The ldap.ora file resides in ORACLE_HOME\network\admin.
A process that resides on the server and whose responsibility is to listen for incoming client connection requests and manage the traffic to the server.
When a client requests a network session with a database server, a listener receives the actual request. If the client information matches the listener information, then the listener grants a connection to the database server.
A configuration file for the listener that identifies the:
-
Listener name
-
Protocol addresses on which it is accepting connection requests
-
Services for which it is listening
The listener.ora file resides in ORACLE_HOME\network\admin.
An Oracle Database 11g Release 2 (11.2) does not require identification of the database service because of service registration. However, static service configuration is required for an Oracle Database 11g Release 2 (11.2) if you plan to use Oracle Enterprise Manager.
A Naming method that resolves a net service name into a connect descriptor. This name is configured and stored in the tnsnames.ora file on each individual client.
A resolution method used by a client application to resolve a connect identifier to a network address when attempting to connect to a database service. Oracle Net Services supports the following naming methods:
-
Local naming
-
Directory naming
-
Easy Connecting naming
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NIS External naming
A simple name for a service that resolves to a connect descriptor. Users initiate a connect request by passing a username and password along with a net service name in a connect string for the service to which they want to connect:
SQL> CONNECT username@net_service_identifier Enter password: password
Depending on your needs, net service names can be stored in a variety of places, including:
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Local configuration file, tnsnames.ora, on each client
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Directory server
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External naming service, such as Network Information Service (NIS) or Cell Directory Service (CDS)
● operating system authenticated connections
Windows login credentials can be used to authenticate users connecting to an Oracle Database. The benefits of Windows native authentication include:
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Enabling users to connect to multiple Oracle Databases without supplying a username or password
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Centralizing Oracle Database user authorization information in Windows, which frees Oracle Database from storing or managing user passwords
The initialization file parameter OS_AUTHENT_PREFIX enables users to specify a prefix that Oracle uses to authenticate users attempting to connect to the database. Oracle concatenates the value of this parameter to the beginning of the user's operating system account name. When a connection request is attempted, Oracle compares the prefixed username with Oracle usernames in the database.
The default value of this parameter is "" (a null string), thereby eliminating the addition of any prefix to operating system account names. In earlier releases, OPS$ (short for operating system specific) was the default setting.
The root of a directory subtree with a relative distinguished name of cn=OracleContext, under which all Oracle software information is kept. There may be one (or multiple) Oracle Context in a directory. An Oracle Context can be associated with a directory naming context.
The Oracle Context can contain the following Oracle entries:
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Connect identifiers for use with Oracle Net Services directory naming to make database connections
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Enterprise user security for use with Oracle Advanced Security
The directory path to install Oracle components (for example, c:\app\username\product\11.2.0\dbhome_n where n is the number of the Oracle home). You are prompted to enter an Oracle home in the Path field of the Oracle Universal Installer File Locations window.
A set of rules that determine what can be stored in an LDAP-compliant directory server. Oracle has its own schema that is applied to many types of Oracle entries, including Oracle Net Services entries. The Oracle schema for Oracle Net Services entries includes the attributes the entries may contain.
A networking communication layer that is responsible for establishing and maintaining the connection between the client application and server, and exchanging messages between them.
An address that identifies the network address of a network object.
When a connection is made, the client and the receiver of the request, such as the listener, or Oracle Connection Manager, are configured with identical protocol addresses. The client uses this address to send the connection request to a particular network object location, and the recipient "listens" for requests on this address. It is important to install the same protocols for the client and the connection recipient, as well as configure the same addresses.
A set of tables located in any Oracle database accessible to the Oracle Management Server. Oracle Management Server uses a repository to store all system data and application data, information about the state of managed nodes distributed throughout the environment, as well as information about the separately licensable management packs.
A feature by which the PMON process (an instance background process) automatically registers information with a listener. Because this information is registered with the listener, the listener.ora file does not need to be configured with this static information.
Service registration provides the listener with the following information:
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Service name(s) for each running instance of the database
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Instance name(s) of the database
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Service handlers (dispatchers and dedicated servers) available for each instance
This allows the listener to direct a client's request appropriately.
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Dispatcher, instance, and node load information
This allows the listener to determine which dispatcher can best handle a client connection's request. If all dispatchers are blocked, the listener can spawn a dedicated server for the connection.
This information allows the listener to determine how best to service a client connection request.
The Oracle system identifier that distinguishes the database from all other databases on your computer. The SID automatically defaults to the database name portion of the global database name (sales in the example sales.us.example.com) until you reach eight characters or enter a period. You can accept or change the default value.
A configuration file for the client or server that specifies the:
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Client domain to append to unqualified service names or net service names
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Order of naming methods for the client to use when resolving a name
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Logging and tracing features to use
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Route of connections
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External naming parameters
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Oracle Advanced Security parameters
The sqlnet.ora file resides in ORACLE_HOME\network\admin.
See SID.
Microsoft Windows Terminal Server is a Windows thin-client terminal server, a product that adds support for multiple, simultaneous client sessions on the Windows Server. Windows Terminal Server provides an operating system graphical user interface (GUI) to users of Oracle databases.
A configuration file that contains net service names mapped to connect descriptors. This file is used for the local naming method. The tnsnames.ora file resides in ORACLE_HOME\network\admin.
Oracle Universal Installer option that performs a default configuration of a connection between Oracle Database Client and Oracle Database. It configures the following:
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One net service name in the tnsnames.ora file.
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local naming and easy connect naming methods in the sqlnet.ora file.
When Oracle Database Client attempts to connect, it tries local naming first, followed by easy connect naming.
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GlossaryGlossary
A script that can be generated in Oracle Warehouse Builder that extracts and loads data from SAP systems.
A unit of work for a process flow. See also process flow.
A container within Oracle Database that stores data in a multidimensional format. Analytic workspaces provide the best support for OLAP processing.
A cross-platform, reusable object that contains the information required to perform a specific set of tasks against a specific technology or set of technologies, for example data integration or data transformation tasks.
A mapping that contains an association with a Code Template. Typically used to extract or load data (both with and without transformations) from non-Oracle databases, such as IBM DB2 and Microsoft SQL Server.
The agent that runs the Code Templates in the Oracle Containers for J2EE (OC4J) server. You must start the Control Center Agent before you deploy Code Templates or CT mappings. Also referred to as the J2EE Runtime.
The graphical console of the Control Center Service for centrally viewing and managing all aspects of deployment and execution. Provides access to the information stored in the active configuration. Includes update capabilities to enable management of your data system's life cycle.
A service that runs outside the database, which can monitor and execute things that cannot be run directly in the database, such as: PL*SQL scripts, SQL*Loader, and shell scripts. Enables deployment of Oracle Warehouse Builder mappings and processes to targets (databases, and so on), and the execution of these mappings and processes.
A data object that contains measures, and links to one or more dimensions. The axes of a cube contain dimension members, and the body of the cube contains measure values.
Processes that provide data monitoring by validating data against a set of data rules to determine which records comply and which do not.
Metadata (as definitions) about data profiling results, which can be bound to the profiled data objects, and then be available in any context in which the profiled objects are used in ETL.
A set of operations, which are specified in a mapping, that change source data into consistent, compatible output for a target.
A script that can be generated in Oracle Warehouse Builder that creates or drops database objects.
The parameter for an object that specifies it is to be deployed. By default this parameter is selected. To prevent an object from being deployed, clear this parameter.
The parameter for an object that specifies it is to be deployed. By default this parameter is selected. To prevent an object from being deployed, clear this parameter.
The process of creating physical objects in a target location according to the logical objects defined in an Oracle Warehouse Builder workspace.
An object that contains additional metadata to identify and categorize data. Same as dimensional object. Can be a cube.
A descriptive characteristic of a dimension member, having a name and a data type.
The process of extracting data from its source location, transforming it as defined in a mapping, and loading it into target objects (or schemas). ETL stands for extract, transform, and load.
The process of running the code for the ETL logic that is defined in the deployed objects to instantiate the logic within the objects.
Mini-applications or task-flows that perform a specific sequence of tasks in Oracle Warehouse Builder.
Non-hierarchical, non-object-oriented file structures in plain text comma-delimited or tab-separated format, ASCII format, or proprietary binary formats.
Structures in which to organize all or some objects within a target module based on specific object characteristics. For example, you may create user folders to group tables based on their functionality (sales, marketing, administration and so forth).
A structure that uses ordered levels to organize data. Oracle Warehouse Builder uses hierarchies to define relationships between adjacent levels in time dimensions.
Refer to Control Center Agent (CCA). Also, sometimes called Java Runtime.
Object that stores the connection information to the various files, databases, and applications that Oracle Warehouse Builder accesses for extracting and loading data. Locations also store connection information to ETL management tools and Business Intelligence tools.
An object that contains operations for extraction, transformation, and loading (ETL) that moves data from sources to targets.
The representation of an operation for a distinct task you want to perform in a mapping. For example, operations include extracting data, loading data, and transforming data.
Relating to the match merge feature, a match bin set consists of one or more similar records.
A container object that appears in the Projects Navigator and that corresponds to a specific location in the Locations Navigator. A module can correspond to only one metadata location and data location at a time.
The Oracle Warehouse Builder scripting API, which is based on the Java implementation of Tcl called Jacl.
A subset of OMB*Plus that provides scripting commands for manipulating the user interface in Oracle Warehouse Builder. Also OMU-prefixed commands ('U' for UI component).
Oracle Warehouse Builder contains pre-built operators for transformations, mappings, names and addresses, and so forth. Operators in Oracle Warehouse Builder are customizable and take advantage of the library of PL/SQL functions, procedures, package functions, and package procedures for Oracle Database. See also mapping operator.
Oracle Data Integrator (ODI). See Oracle Fusion Middleware Developer's Guide for Oracle Data Integrator.
● Oracle Warehouse Builder Repository
The single, unified repository for the database instance, which is pre-seeded with a schema and database objects. The run time environment and the design environment reside in this single repository. The repository schema, named OWBSYS, gets created when you install Oracle Database.
A reusable grouping of mapping operators that works as a single operator. Similar in concept to a function in a programming language.
An object that describes dependencies and activities between Oracle Warehouse Builder mappings and external processes, applets, or applications. Process flows begin with a start activity and conclude with an end activity and can also start other process flows. Compare to schedule. See also activity.
The highest-level and largest object in Oracle Warehouse Builder workspace. Each project contains the metadata and definitions for objects in the data system that contains the sources and targets.
A target schema that contains relational data objects such as tables, views, materialized views, and sequences. All of the data for a data store or data warehouse is contained in these objects.
Refer to Oracle Warehouse Builder Repository.
A file or script that can be generated in Oracle Warehouse Builder that extracts and transports data from file sources.
A set of operators that enable manipulation of a set of input rows, which return another set of rows of the same or different cardinality. Can return a set of output rows that can be queried like a physical table.
A container that holds the metadata definitions of all your data warehouse objects. Each target module corresponds to a target location that represents the physical location where the objects are stored.
A schema that contains the data objects that store your data warehouse data. You can design a relational target schema or a dimensional target schema.
Type of module that enables rapid copying of a group of related database objects in one database, to be pasted or inserted into another database.
Prebuilt operators that enable commonly performed operations such as filtering, joining, and sorting. Oracle Warehouse Builder also includes prebuilt operators for complex operations such as merging data, cleansing data, or profiling data.
A folder you can create to organize all or some objects in a target module based on specific object characteristics. Related tables and views that must be generated or deployed can be placed under a common folder. For example, you may create user folders to group tables based on their functionality (sales, marketing, administration and so forth).
The process of verifying metadata definitions and configuration parameters to ensure that data object definitions are complete and that scripts can be generated and deployed.
A dimension in which hierarchical relationships are defined by a parent dimension attribute and a child dimension attribute.
Oracle Warehouse Builder structure that contains all the related projects and their objects. Graphically displayed as the canvas in the Design Center where Oracle Warehouse Builder windows, navigators, wizards, and dialog boxes are laid out to create a work environment that one or more users log in to.
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