金沙js8331MySQL执行update语句和原数据相同会再次执行吗

背景

金沙js8331,本文首要测量检验MySQL推行update语句时,针对与原数据风流浪漫致的update语句会在MySQL内部重新施行吗?

测量检验意况

MySQL5.7.25 Centos 7.4

binlog_format为ROW

参数

root@localhost : (none) 04:53:15 show variables like 'binlog_row_image';+------------------+-------+| Variable_name | Value |+------------------+-------+| binlog_row_image | FULL |+------------------+-------+1 row in set (0.00 sec)root@localhost : (none) 04:53:49 show variables like 'binlog_format'; +---------------+-------+| Variable_name | Value |+---------------+-------+| binlog_format | ROW |+---------------+-------+1 row in set (0.00 sec)root@localhost : test 05:15:14 show variables like 'transaction_isolation';+-----------------------+-----------------+| Variable_name | Value |+-----------------------+-----------------+| transaction_isolation | REPEATABLE-READ |+-----------------------+-----------------+1 row in set (0.00 sec)

测验步骤

session1

root@localhost : test 04:49:48 begin;Query OK, 0 rows affected (0.00 sec)root@localhost : test 04:49:52 select * from test where id =1;+----+------+------+------+| id | sid | mid | name |+----+------+------+------+| 1 | 999 | 871 | NW |+----+------+------+------+1 row in set (0.00 sec)root@localhost : (none) 04:54:03 show engine innodb statusGshow master statusG...---LOG---Log sequence number 12090390Log flushed up to 12090390Pages flushed up to 12090390Last checkpoint at 120903810 pending log flushes, 0 pending chkp writes33 log i/o's done, 0.00 log i/o's/second*************************** 1. row *************************** File: mysql-bin.000001 Position: 154 Binlog_Do_DB: Binlog_Ignore_DB: Executed_Gtid_Set: 1 row in set (0.00 sec)

session2

root@localhost : test 04:47:45 update test set sid=55 where id =1;Query OK, 1 row affected (0.01 sec)Rows matched: 1 Changed: 1 Warnings: 0root@localhost : (none) 04:54:03 show engine innodb statusGshow master statusG...---LOG---Log sequence number 12091486Log flushed up to 12091486Pages flushed up to 12091486Last checkpoint at 120914770 pending log flushes, 0 pending chkp writes39 log i/o's done, 0.00 log i/o's/second*************************** 1. row *************************** File: mysql-bin.000001 Position: 500 Binlog_Do_DB: Binlog_Ignore_DB: Executed_Gtid_Set: 8392d215-4928-11e9-a751-0242ac110002:11 row in set (0.00 sec)

session1

root@localhost : test 04:49:57 update test set sid=55 where id =1; Query OK, 0 rows affected (0.00 sec)Rows matched: 1 Changed: 0 Warnings: 0root@localhost : (none) 04:54:03 show engine innodb statusGshow master statusG...---LOG---Log sequence number 12091486Log flushed up to 12091486Pages flushed up to 12091486Last checkpoint at 120914770 pending log flushes, 0 pending chkp writes39 log i/o's done, 0.00 log i/o's/second*************************** 1. row *************************** File: mysql-bin.000001 Position: 500 Binlog_Do_DB: Binlog_Ignore_DB: Executed_Gtid_Set: 8392d215-4928-11e9-a751-0242ac110002:11 row in set (0.00 sec)root@localhost : test 04:52:05 select * from test where id =1;+----+------+------+------+| id | sid | mid | name |+----+------+------+------+| 1 | 999 | 871 | NW |+----+------+------+------+1 row in set (0.00 sec)root@localhost : test 04:52:42 commit;Query OK, 0 rows affected (0.00 sec)root@localhost : test 04:52:52 select * from test where id =1;+----+------+------+------+| id | sid | mid | name |+----+------+------+------+| 1 | 55 | 871 | NW |+----+------+------+------+1 row in set (0.00 sec)

总结

binlog_format=rowbinlog_row_image=FULL时,由于MySQL 须要在
binlog
里面著录全数的字段,所以在读数据的时候就能够把具备数据都读出来,那么重复数据的update不会实行。即MySQL
调用了 InnoDB 引擎提供的“校订为
(1,55卡塔尔国”这些接口,不过引擎发掘实价值与原本一样,不改过,直接回到

binlog_format为STATEMENT

参数

root@localhost : (none) 04:53:15 show variables like 'binlog_row_image';+------------------+-------+| Variable_name | Value |+------------------+-------+| binlog_row_image | FULL |+------------------+-------+1 row in set (0.00 sec)root@localhost : (none) 05:16:08 show variables like 'binlog_format';+---------------+-----------+| Variable_name | Value |+---------------+-----------+| binlog_format | STATEMENT |+---------------+-----------+1 row in set (0.00 sec)root@localhost : test 05:15:14 show variables like 'transaction_isolation';+-----------------------+-----------------+| Variable_name | Value |+-----------------------+-----------------+| transaction_isolation | REPEATABLE-READ |+-----------------------+-----------------+1 row in set (0.00 sec)

测量试验步骤

session1

root@localhost : test 05:16:42 begin;Query OK, 0 rows affected (0.00 sec)root@localhost : test 05:16:44 select * from test where id =1;+----+------+------+------+| id | sid | mid | name |+----+------+------+------+| 1 | 111 | 871 | NW |+----+------+------+------+1 row in set (0.00 sec)root@localhost : (none) 05:16:51 show engine innodb statusGshow master statusG...---LOG---Log sequence number 12092582Log flushed up to 12092582Pages flushed up to 12092582Last checkpoint at 120925730 pending log flushes, 0 pending chkp writes45 log i/o's done, 0.00 log i/o's/second*************************** 1. row *************************** File: mysql-bin.000001 Position: 154 Binlog_Do_DB: Binlog_Ignore_DB: Executed_Gtid_Set: 1 row in set (0.00 sec)

session2

root@localhost : test 05:18:30 update test set sid=999 where id =1;Query OK, 1 row affected (0.00 sec)Rows matched: 1 Changed: 1 Warnings: 0root@localhost : (none) 05:18:47 show engine innodb statusGshow master statusG...---LOG---Log sequence number 12093678Log flushed up to 12093678Pages flushed up to 12093678Last checkpoint at 120936690 pending log flushes, 0 pending chkp writes51 log i/o's done, 0.14 log i/o's/second*************************** 1. row *************************** File: mysql-bin.000001 Position: 438 Binlog_Do_DB: Binlog_Ignore_DB: Executed_Gtid_Set: 8392d215-4928-11e9-a751-0242ac110002:11 row in set (0.00 sec)

session1

root@localhost : test 05:16:47 update test set sid=999 where id =1;Query OK, 0 rows affected (0.00 sec)Rows matched: 1 Changed: 0 Warnings: 0root@localhost : (none) 05:20:03 show engine innodb statusGshow master statusG...---LOG---Log sequence number 12094504Log flushed up to 12094504Pages flushed up to 12094504Last checkpoint at 120944950 pending log flushes, 0 pending chkp writes56 log i/o's done, 0.00 log i/o's/second*************************** 1. row *************************** File: mysql-bin.000001 Position: 438 Binlog_Do_DB: Binlog_Ignore_DB: Executed_Gtid_Set: 8392d215-4928-11e9-a751-0242ac110002:11 row in set (0.00 sec)root@localhost : test 05:19:33 select * from test where id =1; +----+------+------+------+| id | sid | mid | name |+----+------+------+------+| 1 | 999 | 871 | NW |+----+------+------+------+1 row in set (0.00 sec)root@localhost : test 05:20:44 commit;Query OK, 0 rows affected (0.01 sec)root@localhost : test 05:20:57 select * from test where id =1;+----+------+------+------+| id | sid | mid | name |+----+------+------+------+| 1 | 999 | 871 | NW |+----+------+------+------+1 row in set (0.00 sec)

总结

在binlog_format=statement和binlog_row_image=FULL时,InnoDB内部认真实行了update语句,即“把这些值改进成
(1,999卡塔尔“这几个操作,该加锁的加锁,该更新的换代。

好了,以上正是那篇文章的全体内容了,希望本文的剧情对大家的读书也许办事富有自然的参照他事他说加以调查学习价值,多谢大家对台本之家的支撑。

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