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如何进行 mysqldump 单表备份加 –single-transaction –master-data= 2 参数执行过程的内部剖析
今天就跟大家聊聊有关如何进行 mysqldump 单表备份加 –single-transaction –master-data= 2 参数执行过程的内部剖析，可能很多人都不太了解，为了让大家更加了解，丸趣 TV 小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。
开启 general_log:
mysql(mdba@localhost:(none) 01:08:55) set global general_log=on;
Query OK, 0 rows affected (0.02 sec)
mysql(mdba@localhost:(none) 01:09:07) show variables like %general%
| Variable_name | Value |
| general_log | ON |
| general_log_file | /usr/local/mysql/data/localhost.log |
2 rows in set (0.00 sec)
mysql(mdba@localhost:(none) 01:31:43) show databases;
| Database |
| information_schema |
| bbb |
| credit |
| e_contract |
| ixinnuo_sjcj |
| ixinnuo_sjcj-_T |
| mysql |
| percona |
| performance_schema |
| sys |
| test |
| whpmap |
12 rows in set (0.05 sec)
mysql(mdba@localhost:(none) 01:31:46) use credit
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql(mdba@localhost:credit 01:32:02) show tables;
| Tables_in_credit |
| f_audit |
| f_audit_bak_20170504 |
2 rows in set (0.00 sec)
例如备份 credit 库下面的 f_audit 表，使用 –single-transaction –master-data= 2 参数:
[root@localhost tmp]# mysqldump -umdba -pdsf0723 –single-transaction –master-data=2 credit f_audit /tmp/f_audit.sql
查看 general_log:
[root@localhost tmp]# cat /usr/local/mysql/data/localhost.log
/opt/app/mysql/5.7.18/bin/mysqld, Version: 5.7.18-log (MySQL Community Server (GPL)). started with:
Tcp port: 3306 Unix socket: /tmp/mysql.sock
Time Id Command Argument
2017-08-31T05:09:09.189375Z 19513 Query show variables like %gen%
2017-08-31T05:09:24.603322Z 19513 Query SELECT DATABASE()
2017-08-31T05:09:24.604041Z 19513 Init DB credit
2017-08-31T05:09:24.605173Z 19513 Query show databases
2017-08-31T05:09:24.605838Z 19513 Query show tables
2017-08-31T05:09:24.605976Z 19513 Field List f_audit
2017-08-31T05:09:24.606416Z 19513 Field List f_audit_bak_20170504
2017-08-31T05:09:26.575331Z 19513 Query show tables
2017-08-31T05:11:18.126829Z 19514 Connect mdba@localhost on using Socket
2017-08-31T05:11:18.126927Z 19514 Query /*!40100 SET @@SQL_MODE= */
2017-08-31T05:11:18.130352Z 19514 Query /*!40103 SET TIME_ZONE= +00:00 */
2017-08-31T05:11:18.130450Z 19514 Query FLUSH /*!40101 LOCAL */ TABLES
2017-08-31T05:11:18.140266Z 19514 Query FLUSH TABLES WITH READ LOCK
2017-08-31T05:11:18.140318Z 19514 Query SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ
2017-08-31T05:11:18.140355Z 19514 Query START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */
2017-08-31T05:11:18.140417Z 19514 Query SHOW VARIABLES LIKE gtid\_mode
2017-08-31T05:11:18.150840Z 19514 Query SHOW MASTER STATUS
2017-08-31T05:11:18.168898Z 19514 Query UNLOCK TABLES
2017-08-31T05:11:18.181199Z 19514 Query SELECT LOGFILE_GROUP_NAME, FILE_NAME, TOTAL_EXTENTS, INITIAL_SIZE, ENGINE, EXTRA FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = UNDO LOG AND FILE_NAME IS NOT NULL AND LOGFILE_GROUP_NAME IS NOT NULL AND LOGFILE_GROUP_NAME IN (SELECT DISTINCT LOGFILE_GROUP_NAME FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = DATAFILE AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA= credit AND TABLE_NAME IN ( f_audit))) GROUP BY LOGFILE_GROUP_NAME, FILE_NAME, ENGINE, TOTAL_EXTENTS, INITIAL_SIZE ORDER BY LOGFILE_GROUP_NAME
2017-08-31T05:11:18.210240Z 19514 Query SELECT DISTINCT TABLESPACE_NAME, FILE_NAME, LOGFILE_GROUP_NAME, EXTENT_SIZE, INITIAL_SIZE, ENGINE FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = DATAFILE AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA= credit AND TABLE_NAME IN ( f_audit)) ORDER BY TABLESPACE_NAME, LOGFILE_GROUP_NAME
2017-08-31T05:11:18.220125Z 19514 Query SHOW VARIABLES LIKE ndbinfo\_version
2017-08-31T05:11:18.221667Z 19514 Init DB credit
2017-08-31T05:11:18.221712Z 19514 Query SHOW TABLES LIKE f\_audit
2017-08-31T05:11:18.221834Z 19514 Query SAVEPOINT sp
2017-08-31T05:11:18.221887Z 19514 Query show table status like f\_audit
2017-08-31T05:11:18.222054Z 19514 Query SET SQL_QUOTE_SHOW_CREATE=1
2017-08-31T05:11:18.222100Z 19514 Query SET SESSION character_set_results = binary
2017-08-31T05:11:18.222142Z 19514 Query show create table `f_audit`
2017-08-31T05:11:18.222231Z 19514 Query SET SESSION character_set_results = utf8
2017-08-31T05:11:18.222287Z 19514 Query show fields from `f_audit`
2017-08-31T05:11:18.222614Z 19514 Query show fields from `f_audit`
2017-08-31T05:11:18.222940Z 19514 Query SELECT /*!40001 SQL_NO_CACHE */ * FROM `f_audit`
2017-08-31T05:11:18.223074Z 19514 Query SET SESSION character_set_results = binary
2017-08-31T05:11:18.223116Z 19514 Query use `credit`
2017-08-31T05:11:18.223165Z 19514 Query select @@collation_database
2017-08-31T05:11:18.223224Z 19514 Query SHOW TRIGGERS LIKE f\_audit
2017-08-31T05:11:18.223465Z 19514 Query SET SESSION character_set_results = utf8
2017-08-31T05:11:18.223509Z 19514 Query ROLLBACK TO SAVEPOINT sp
2017-08-31T05:11:18.223547Z 19514 Query RELEASE SAVEPOINT sp
2017-08-31T05:11:18.281441Z 19514 Quit
发现其执行了 FLUSH TABLES WITH READ LOCK:
2017-08-31T05:11:18.130450Z 19514 Query FLUSH /*!40101 LOCAL */ TABLES
2017-08-31T05:11:18.140266Z 19514 Query FLUSH TABLES WITH READ LOCK
通过进一步测试发现 mysqldump 备份的时候只使用 –single-transaction 不使用 –master-data= 2 参数是不会进行锁表的。
不加 –master-data= 2 参数:
[root@localhost tmp]#mysqldump -umdba -pdsf0723 –single-transaction credit f_audit f_audit.sql
查看 general_log:
2017-08-31T05:24:05.890881Z 19516 Connect mdba@localhost on using Socket
2017-08-31T05:24:05.890984Z 19516 Query /*!40100 SET @@SQL_MODE= */
2017-08-31T05:24:05.891037Z 19516 Query /*!40103 SET TIME_ZONE= +00:00 */
2017-08-31T05:24:05.891478Z 19516 Query SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ
2017-08-31T05:24:05.891520Z 19516 Query START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */
2017-08-31T05:24:05.891589Z 19516 Query SHOW VARIABLES LIKE gtid\_mode
2017-08-31T05:24:05.893983Z 19516 Query UNLOCK TABLES
2017-08-31T05:24:05.894099Z 19516 Query SELECT LOGFILE_GROUP_NAME, FILE_NAME, TOTAL_EXTENTS, INITIAL_SIZE, ENGINE, EXTRA FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = UNDO LOG AND FILE_NAME IS NOT NULL AND LOGFILE_GROUP_NAME IS NOT NULL AND LOGFILE_GROUP_NAME IN (SELECT DISTINCT LOGFILE_GROUP_NAME FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = DATAFILE AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA= credit AND TABLE_NAME IN ( f_audit))) GROUP BY LOGFILE_GROUP_NAME, FILE_NAME, ENGINE, TOTAL_EXTENTS, INITIAL_SIZE ORDER BY LOGFILE_GROUP_NAME
2017-08-31T05:24:05.911788Z 19516 Query SELECT DISTINCT TABLESPACE_NAME, FILE_NAME, LOGFILE_GROUP_NAME, EXTENT_SIZE, INITIAL_SIZE, ENGINE FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = DATAFILE AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA= credit AND TABLE_NAME IN ( f_audit)) ORDER BY TABLESPACE_NAME, LOGFILE_GROUP_NAME
2017-08-31T05:24:05.916870Z 19516 Query SHOW VARIABLES LIKE ndbinfo\_version
2017-08-31T05:24:05.918150Z 19516 Init DB credit
2017-08-31T05:24:05.918208Z 19516 Query SHOW TABLES LIKE f\_audit
2017-08-31T05:24:05.918336Z 19516 Query SAVEPOINT sp
2017-08-31T05:24:05.918390Z 19516 Query show table status like f\_audit
2017-08-31T05:24:05.918558Z 19516 Query SET SQL_QUOTE_SHOW_CREATE=1
2017-08-31T05:24:05.918603Z 19516 Query SET SESSION character_set_results = binary
2017-08-31T05:24:05.918648Z 19516 Query show create table `f_audit`
2017-08-31T05:24:05.918730Z 19516 Query SET SESSION character_set_results = utf8
2017-08-31T05:24:05.918786Z 19516 Query show fields from `f_audit`
2017-08-31T05:24:05.919114Z 19516 Query show fields from `f_audit`
2017-08-31T05:24:05.919417Z 19516 Query SELECT /*!40001 SQL_NO_CACHE */ * FROM `f_audit`
2017-08-31T05:24:05.919547Z 19516 Query SET SESSION character_set_results = binary
2017-08-31T05:24:05.919592Z 19516 Query use `credit`
2017-08-31T05:24:05.919639Z 19516 Query select @@collation_database
2017-08-31T05:24:05.919698Z 19516 Query SHOW TRIGGERS LIKE f\_audit
2017-08-31T05:24:05.919999Z 19516 Query SET SESSION character_set_results = utf8
2017-08-31T05:24:05.920064Z 19516 Query ROLLBACK TO SAVEPOINT sp
2017-08-31T05:24:05.920107Z 19516 Query RELEASE SAVEPOINT sp
2017-08-31T05:24:05.971293Z 19516 Quit
发现并没有执行 FLUSH TABLES WITH READ LOCK.
只使用 –master-data= 2 参数为了获取 show master status，会执行 FLUSH TABLES WITH READ LOCK 的全局锁，在业务低峰期，mysql 获取全局锁会很快, 但在业务高峰期又有很多库表的情况下是不建议执行全局锁的，
因此 mysqldump 备份尽量放在业务低峰期做，或者备份时直接去掉 –master-data= 2 参数.
看完上述内容，你们对如何进行 mysqldump 单表备份加 –single-transaction –master-data= 2 参数执行过程的内部剖析有进一步的了解吗？如果还想了解更多知识或者相关内容，请关注丸趣 TV 行业资讯频道，感谢大家的支持。
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