Oracle 重建索引脚本

      索引是提高数据库查询性能的有力武器。没有索引，就好比图书馆没有图书标签一样，找一本书自己想要的书比登天还难。然而索引在使用的过程中，尤其是在批量的DML的情形下会产生相应的碎片，以及B树高度会发生相应变化，因此可以对这些变化较大的索引进行重构以提高性能。N久以前Oracle建议我们定期重建那些高度为4，已删除的索引条目至少占有现有索引条目总数的20%的这些表上的索引。但Oracle现在强烈建议不要定期重建索引。具体可以参考文章：Oracle 重建索引的必要性。尽管如此重建索引还是有必要的，只是不建议定期。本文给出了重建索引的脚本供大家参考。
 
1、重建索引shell脚本

robin@SZDB:~/dba_scripts/custom/bin> more rebuild_unbalanced_indices.sh 
# +-------------------------------------------------------+
# +    Rebulid unblanced indices                          |
# +    Author : Leshami                                   | 
# +    Parameter : No                                     |
# +    Blog : http://blog.csdn.net/leshami                | 
# +-------------------------------------------------------+

#!/bin/bash 
# --------------------
# Define variable
# --------------------

if [ -f ~/.bash_profile ]; then
. ~/.bash_profile
fi

DT=`date +%Y%m%d`;             export DT
RETENTION=1
LOG_DIR=/tmp
LOG=${LOG_DIR}/rebuild_unbalanced_indices_${DT}.log
DBA=Leshami@12306.cn

# ------------------------------------
# Loop all instance in current server
# -------------------------------------
echo "Current date and time is : `/bin/date`">>${LOG}

for db in `ps -ef | grep pmon | grep -v grep |grep -v asm |awk '{print $8}'|cut -c 10-`
do
    echo "$db"
    export ORACLE_SID=$db
    echo "Current DB is $db" >>${LOG}
    echo "===============================================">>${LOG}
    $ORACLE_HOME/bin/sqlplus -S /nolog @/users/robin/dba_scripts/custom/sql/rebuild_unbalanced_indices.sql>>${LOG}
done;

echo "End of rebuilding index for all instance at : `/bin/date`">>${LOG}
# -------------------------------------
# Check log file 
# -------------------------------------
status=`grep "ORA-" ${LOG}`
if [ -z $status ];then
    mail -s "Succeeded rebuilding indices on `hostname`  !!!" ${DBA} <${LOG}
else
    mail -s "Failed rebuilding indices on `hostname`  !!!" ${DBA} <${LOG}
fi

# ------------------------------------------------
# Removing files older than $RETENTION parameter 
# ------------------------------------------------

find ${LOG_DIR} -name "rebuild_unb*" -mtime +$RETENTION -exec rm {} \;

exit

2、重建索引调用的SQL脚本

robin@SZDB:~/dba_scripts/custom/sql> more rebuild_unbalanced_indices.sql 
conn / as sysdba
set serveroutput on;
DECLARE
   resource_busy               EXCEPTION;
   PRAGMA EXCEPTION_INIT (resource_busy, -54);
   c_max_trial        CONSTANT PLS_INTEGER := 10;
   c_trial_interval   CONSTANT PLS_INTEGER := 1;
   pmaxheight         CONSTANT INTEGER := 3;
   pmaxleafsdeleted   CONSTANT INTEGER := 20;

   CURSOR csrindexstats
   IS
      SELECT NAME,
             height,
             lf_rows AS leafrows,
             del_lf_rows AS leafrowsdeleted
        FROM index_stats;

   vindexstats                 csrindexstats%ROWTYPE;

   CURSOR csrglobalindexes
   IS
      SELECT owner,index_name, tablespace_name
        FROM dba_indexes
       WHERE partitioned = 'NO'
        AND owner IN ('GX_ADMIN');

   CURSOR csrlocalindexes
   IS
      SELECT index_owner,index_name, partition_name, tablespace_name
        FROM dba_ind_partitions
       WHERE status = 'USABLE'
        AND index_owner IN ('GX_ADMIN');

   trial                       PLS_INTEGER;
   vcount                      INTEGER := 0;
BEGIN
   trial := 0;

   /* Global indexes */
   FOR vindexrec IN csrglobalindexes
   LOOP
      EXECUTE IMMEDIATE
         'analyze index ' || vindexrec.owner ||'.'|| vindexrec.index_name || ' validate structure';

      OPEN csrindexstats;

      FETCH csrindexstats INTO vindexstats;

      IF csrindexstats%FOUND
      THEN
         IF    (vindexstats.height > pmaxheight)
            OR (    vindexstats.leafrows > 0
                AND vindexstats.leafrowsdeleted > 0
                AND (vindexstats.leafrowsdeleted * 100 / vindexstats.leafrows) >
                       pmaxleafsdeleted)
         THEN
            vcount := vcount + 1;
            DBMS_OUTPUT.PUT_LINE (
               'Rebuilding index ' || vindexrec.owner ||'.'|| vindexrec.index_name || '...');

           <<alter_index>>
            BEGIN
               EXECUTE IMMEDIATE
                     'alter index '
                  || vindexrec.owner ||'.'
                  || vindexrec.index_name
                  || ' rebuild'
                  || ' parallel nologging compute statistics'
                  || ' tablespace '
                  || vindexrec.tablespace_name;
            EXCEPTION
               WHEN resource_busy OR TIMEOUT_ON_RESOURCE
               THEN
                  DBMS_OUTPUT.PUT_LINE (
                     'alter index - busy and wait for 1 sec');
                  DBMS_LOCK.sleep (c_trial_interval);

                  IF trial <= c_max_trial
                  THEN
                     GOTO alter_index;
                  ELSE
                     DBMS_OUTPUT.PUT_LINE (
                           'alter index busy and waited - quit after '
                        || TO_CHAR (c_max_trial)
                        || ' trials');
                     RAISE;
                  END IF;
               WHEN OTHERS
               THEN
                  DBMS_OUTPUT.PUT_LINE ('alter index err ' || SQLERRM);
                  RAISE;
            END;
         END IF;
      END IF;

      CLOSE csrindexstats;
   END LOOP;

   DBMS_OUTPUT.PUT_LINE ('Global indices rebuilt: ' || TO_CHAR (vcount));
   vcount := 0;
   trial := 0;

   /* Local indexes */
   FOR vindexrec IN csrlocalindexes
   LOOP
      EXECUTE IMMEDIATE
            'analyze index '
         || vindexrec.index_owner||'.'
         || vindexrec.index_name
         || ' partition ('
         || vindexrec.partition_name
         || ') validate structure';

      OPEN csrindexstats;

      FETCH csrindexstats INTO vindexstats;

      IF csrindexstats%FOUND
      THEN
         IF    (vindexstats.height > pmaxheight)
            OR (    vindexstats.leafrows > 0
                AND vindexstats.leafrowsdeleted > 0
                AND (vindexstats.leafrowsdeleted * 100 / vindexstats.leafrows) >
                       pmaxleafsdeleted)
         THEN
            vcount := vcount + 1;
            DBMS_OUTPUT.PUT_LINE (
               'Rebuilding index ' || vindexrec.index_owner||'.'|| vindexrec.index_name || '...');

           <<alter_partitioned_index>>
            BEGIN
               EXECUTE IMMEDIATE
                     'alter index '
                  || vindexrec.index_owner||'.'
                  || vindexrec.index_name
                  || ' rebuild'
                  || ' partition '
                  || vindexrec.partition_name
                  || ' parallel nologging compute statistics'
                  || ' tablespace '
                  || vindexrec.tablespace_name;
            EXCEPTION
               WHEN resource_busy OR TIMEOUT_ON_RESOURCE
               THEN
                  DBMS_OUTPUT.PUT_LINE (
                     'alter partitioned index - busy and wait for 1 sec');
                  DBMS_LOCK.sleep (c_trial_interval);

                  IF trial <= c_max_trial
                  THEN
                     GOTO alter_partitioned_index;
                  ELSE
                     DBMS_OUTPUT.PUT_LINE (
                           'alter partitioned index busy and waited - quit after '
                        || TO_CHAR (c_max_trial)
                        || ' trials');
                     RAISE;
                  END IF;
               WHEN OTHERS
               THEN
                  DBMS_OUTPUT.PUT_LINE (
                     'alter partitioned index err ' || SQLERRM);
                  RAISE;
            END;
         END IF;
      END IF;

      CLOSE csrindexstats;
   END LOOP;

   DBMS_OUTPUT.PUT_LINE ('Local indices rebuilt: ' || TO_CHAR (vcount));
END;
/
exit;

3、输入日志样本
Current date and time is : Sun Apr 20 02:00:02 HKT 2014
Current DB is SYBO2 ===============================================
Rebuilding index GX_ADMIN.SYN_OUT_DATA_TBL_PK...
Rebuilding index GX_ADMIN.IDX_TDBK_SPLNK_PARENT_REF...
Rebuilding index GX_ADMIN.IDX_TDBK_SPLNK_CHILD_REF...
Rebuilding index GX_ADMIN.PK_TRADE_BROKER_TBL...
Rebuilding index GX_ADMIN.IDX_TDBK_INPUT_DATE...
    ................

4、后记
a、如果同一台服务器上有多个实例，且每个实例有相同的schema，此脚本会轮巡所有实例并根据analyze结果来rebuild。 
a、大家应根据需要作相应调整，如脚本的路径信息等。
b、需要修改相应的schema name。
d、可根据系统环境调整相应的并行度。

5、相关参考
    Oracle 聚簇因子(Clustering factor) 
    Oracle 索引监控(monitor index)
    Oracle 索引监控与外键索引 
    收集统计信息导致索引被监控 
    Oracle 监控索引的使用率
    NULL 值与索引(一)
    NULL 值与索引(二)
    函数使得索引列失效

    Oracle 索引质量分析

    Oracle 重建索引的必要性