mysqldump关于–set-gtid-purged=OFF的使用

数据库的模式中我开启了gtid：
mysql> show variables like ‘%gtid%’;
±---------------------------------±----------+
| Variable_name | Value |
±---------------------------------±----------+
| binlog_gtid_simple_recovery | ON |
| enforce_gtid_consistency | ON |
| gtid_executed_compression_period | 1000 |
| gtid_mode | ON |
| gtid_next | AUTOMATIC |
| gtid_owned | |
| gtid_purged | |
| session_track_gtids | OFF |
±---------------------------------±----------+

我现在数据库中有一world的库，并且在库中有一个country表，现在进行备份时会提示如下警告：

[root@smiletest data]# mysqldump -uroot -p -R -e --triggers --master-data=2 --single-transaction world country >/tmp/countryno.sql
Enter password:
Warning: A partial dump from a server that has GTIDs will by default include the GTIDs of all transactions, even those that changed suppressed parts of the database. If you don’t want to restore GTIDs, pass --set-gtid-purged=OFF. To make a complete dump, pass --all-databases --triggers --routines --events.

我们来对比下加了 --set-gtid-purged=OFF和不加的区别
countryno.sql是没有加–set-gtid-purged=OFF

[root@smiletest data]# mysqldump -uroot -p -R -e --triggers --master-data=2 --single-transaction world country >/tmp/countryno.sql
countryyes.sql是加–set-gtid-purged=OFF

[root@smiletest data]# mysqldump -uroot -p -R -e --triggers --master-data=2 --single-transaction --set-gtid-purged=OFF world country >/tmp/countryyes.sql
Enter password:

没有加–set-gtid-purged=OFF的里面会多几条语句
SET @MYSQLDUMP_TEMP_LOG_BIN = @@SESSION.SQL_LOG_BIN;
SET @@SESSION.SQL_LOG_BIN= 0;
– GTID state at the beginning of the backup
SET @@GLOBAL.GTID_PURGED=‘e024c334-8b64-11e9-80dc-fa163e4bfc29:1-761734’;

现在我们进行导入刚没有加–set-gtid-purged=OFF备份的/tmp/countryno.sql语句
mysql> show master status;
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| mysql-bin.000013 | 85019 | | | e024c334-8b64-11e9-80dc-fa163e4bfc29:1-761735 |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
1 row in set (0.00 sec)

mysql> source /tmp/countryno.sql
Query OK, 0 rows affected (0.00 sec)

mysql> show master status;
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| mysql-bin.000013 | 85019 | | | e024c334-8b64-11e9-80dc-fa163e4bfc29:1-761735 |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
1 row in set (0.00 sec)
结论发现，gtid事务和 Position都没有增加

现在我们进行导入刚加–set-gtid-purged=OFF备份的/tmp/countryyes.sql语句
mysql> drop table country;
Query OK, 0 rows affected (0.01 sec)
mysql> show master status;
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| mysql-bin.000013 | 112669 | | | e024c334-8b64-11e9-80dc-fa163e4bfc29:1-761742 |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
1 row in set (0.00 sec)

mysql> source /tmp/countryyes.sql
Query OK, 0 rows affected (0.00 sec)

mysql> show master status;
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
| mysql-bin.000013 | 139929 | | | e024c334-8b64-11e9-80dc-fa163e4bfc29:1-761747 |
±-----------------±---------±-------------±-----------------±----------------------------------------------+
1 row in set (0.00 sec)

mysql>
结论发现，gtid事务和 Position都增加了

结论

加了–set-gtid-purged=OFF时，在会记录binlog日志，如果不加，不记录binlog日志，所以在我们做主从用了gtid时，用mysqldump备份时就要加–set-gtid-purged=OFF，否则你在主上导入恢复了数据，主没有了binlog日志，同步则不会被同步。