gtid环境下mysqldump对于set-gtid-purged的取值

gtid环境备份的时候,还在为set-gtid-purged=0|1的选择而烦恼吗,一起来分析一下。

[mysql@lxd-vm1@/home/mysql]$ mysqldump --help | grep 'set-gtid-purged' -A 10
  --set-gtid-purged[=name] 
                      Add 'SET @@GLOBAL.GTID_PURGED' to the output. Possible
                      values for this option are ON, OFF and AUTO. If ON is
                      used and GTIDs are not enabled on the server, an error is
                      generated. If OFF is used, this option does nothing. If
                      AUTO is used and GTIDs are enabled on the server, 'SET
                      @@GLOBAL.GTID_PURGED' is added to the output. If GTIDs
                      are disabled, AUTO does nothing. If no value is supplied
                      then the default (AUTO) value will be considered.

从命令提供的注释中可以看出,其实该参数有3种取值:

控制是否在备份文件中添加SET @@GLOBAL.GTID_PURGED语句。

1. set-gtid-purged=0|off 不添加。
2. set-gtid-purged=1|on 如果gtid没有开启,则报错;如果开启gtid,则添加。
3. 如果没有提供set-gtid-purged,默认是auto,如果gtid没有开启,不添加;如果开启gtid,则添加。

mysqldump -h5.5.5.101 -uroot -proot --single-transaction --set-gtid-purged=off lxddb t1 > lxddb_t1.sql
[mysql@lxd-vm1@/home/mysql]$ egrep -v '^$|^--|^/' lxddb_t1.sql 
DROP TABLE IF EXISTS `t1`;
CREATE TABLE `t1` (
  `i1` int(11) NOT NULL DEFAULT '0',
  `i2` int(11) NOT NULL DEFAULT '0',
  `d` date DEFAULT NULL,
  PRIMARY KEY (`i1`,`i2`),
  KEY `k_d` (`d`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
LOCK TABLES `t1` WRITE;
INSERT INTO `t1` VALUES (3,1,'1998-01-01'),(3,2,'1999-01-01'),(3,3,'2000-01-01'),(3,4,'2001-01-01'),(3,5,'2002-01-01');
UNLOCK TABLES;
[mysql@lxd-vm1@/home/mysql]$ 

 

mysqldump -h5.5.5.101 -uroot -proot --single-transaction --set-gtid-purged=on lxddb t1 > lxddb_t1.sql
[mysql@lxd-vm1@/home/mysql]$ egrep -v '^$|^--|^/' lxddb_t1.sql 
SET @MYSQLDUMP_TEMP_LOG_BIN = @@SESSION.SQL_LOG_BIN;
SET @@SESSION.SQL_LOG_BIN= 0;
SET @@GLOBAL.GTID_PURGED='84e06268-dfa5-11e7-b0bc-080027a59108:1-2';
DROP TABLE IF EXISTS `t1`;
CREATE TABLE `t1` (
  `i1` int(11) NOT NULL DEFAULT '0',
  `i2` int(11) NOT NULL DEFAULT '0',
  `d` date DEFAULT NULL,
  PRIMARY KEY (`i1`,`i2`),
  KEY `k_d` (`d`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
LOCK TABLES `t1` WRITE;
INSERT INTO `t1` VALUES (3,1,'1998-01-01'),(3,2,'1999-01-01'),(3,3,'2000-01-01'),(3,4,'2001-01-01'),(3,5,'2002-01-01');
UNLOCK TABLES;
SET @@SESSION.SQL_LOG_BIN = @MYSQLDUMP_TEMP_LOG_BIN;
[mysql@lxd-vm1@/home/mysql]$ 

 

结论:

我们备份,就是可能需要拿来进行恢复,是在master上恢复,还是slave上恢复。

如果是在master上进行恢复,那么就需要生成对应的gtid,所以需要使用set-gtid-purged=off

如果是在slave上进行恢复,那么不需要生成对应的gtid,所以需要使用set-gtid-purged=on

posted @ 2018-12-14 17:50  knowledge-is-power  阅读(949)  评论(0编辑  收藏  举报