在MySQL 5.7版本中，日志记录时间发生了变化，使用了UTC方式来记录日志时间，也就是说这是个世界统一时间，与我们常用的本地时间不协调，因此，初始化MySQL 5.7之后，需要对此做出调整，如下本文的描述。
一、错误日志的时间格式
当前环境
[robin@ydq-mnt ~]$ more /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
[robin@ydq-mnt ~]$ mysql -V
mysql Ver 14.14 Distrib 5.7.19-17, for Linux (x86_64) using 6.2
[root@ydq-mnt ~]# date ###系统时间
Mon Dec 18 14:23:16 CST 2018
[root@ydq-mnt ~]# more /var/log/mysqld.log ###mysql 日志输出信息
2017-12-18T07:50:40.575098Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated.
Please use --explicit_defaults_for_timestamp server option (see do
cumentation for more details).
2017-12-18T07:50:40.576375Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.19-17-57-log) starting as process 9268 ...
2017-12-18T07:50:40.578287Z 0 [Warning] No argument was provided to --log-bin, and --log-bin-index was not used;
so replication may break when this MySQL serve
r acts as a master and has his hostname changed!! Please use '--log-bin=ydq-mnt-bin' to avoid this problem.
2017-12-18T07:50:40.578320Z 0 [Note] WSREP: Setting wsrep_ready to false
2017-12-18T07:50:40.578330Z 0 [Note] WSREP: No pre-stored wsrep-start position found. Skipping position initialization.
2017-12-18T07:50:40.578335Z 0 [Note] WSREP: wsrep_load(): loading provider library '/usr/lib64/galera3/libgalera_smm.so'
2017-12-18T07:50:40.582014Z 0 [Note] WSREP: wsrep_load(): Galera 3.22(r8678538) by Codership Oy
<info@codership.com> loaded successfully.
从上所示，当前的系统时间为mysql日志记录的时间不一致。
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二、系统变量log_timestamps
This variable controls the timestamp time zone of error log messages, and of general query log
and slow query log messages written to files. It does not affect the time zone of general query log
and slow query log messages written to tables (mysql.general_log, mysql.slow_log). Rows
retrieved from those tables can be converted from the local system time zone to any desired time
zone with CONVERT_TZ() or by setting the session time_zone system variable.
Permitted log_timestamps values are UTC (the default) and SYSTEM (local system time zone).
Timestamps are written using ISO 8601 / RFC 3339 format: YYYY-MM-DDThh:mm:ss.uuuuuu plus
a tail value of Z signifying Zulu time (UTC) or hh:mm (an offset from UTC).
This variable was added in MySQL 5.7.2. Before 5.7.2, timestamps in log messages were written
using the local system time zone by default, not UTC. If you want the previous log message time
zone default, set log_timestamps=SYSTEM.
从上描述可知，这个变量是在MySQL 5.7.2中添加的。缺省值为UTC。
如果如要使用缺省时区的时间，修改该参数的值为SYSTEM
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三、修改及验证
mysql> set global log_timestamps='SYSTEM';
Query OK, 0 rows affected (0.00 sec)
[root@ydq-mnt mysql]# vim /etc/percona-xtradb-cluster.conf.d/mysqld.cnf
log_timestamps=SYSTEM
[root@ydq-mnt ~]# systemctl restart mysql
2017-12-18T07:52:41.543983Z 0 [Note] Beginning of list of non-natively partitioned tables
2017-12-18T07:52:41.544128Z 0 [Note] WSREP: Member 0.0 (ydq-mnt) synced with group.
2017-12-18T07:52:41.544138Z 0 [Note] WSREP: Shifting JOINED -> SYNCED (TO: 4163)
2017-12-18T07:52:41.550738Z 8 [Note] WSREP: Synchronized with group, ready for connections
2017-12-18T07:52:41.550755Z 8 [Note] WSREP: This node is synced, setting wsrep_ready to true
2017-12-18T07:52:41.550761Z 8 [Note] WSREP: wsrep_notify_cmd is not defined, skipping notification.
2017-12-18T07:52:41.582207Z 0 [Note] End of list of non-natively partitioned tables
2017-12-18T07:52:43.178826Z 0 [Note] InnoDB: Buffer pool(s) load completed at 171218 15:52:43
2017-12-18T16:24:23.588881+08:00 0 [Note] WSREP: Received shutdown signal. Will sleep for 10 secs before initiating shutdown.
pxc_maint_mode switched to SHUTDOWN
2017-12-18T16:24:33.591354+08:00 0 [Note] WSREP: Stop replication
2017-12-18T16:24:33.591408+08:00 0 [Note] WSREP: Closing send monitor...
2017-12-18T16:24:33.591429+08:00 0 [Note] WSREP: Closed send monitor.
2017-12-18T16:24:33.591453+08:00 0 [Note] WSREP: gcomm: terminating thread
2017-12-18T16:24:33.591477+08:00 0 [Note] WSREP: gcomm: joining thread
2017-12-18T16:24:33.591700+08:00 0 [Note] WSREP: gcomm: closing backend
再次启动及验证，时间显示与系统时间一致。
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