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MySQL中经常遇到事务中的SQL正在执行或执行完成后未提交，如何找出对应的SQL？
1. 查看正在执行的SQL
查看事务中正在执行的SQL方式有多种，例如
1.1 通过processlist查看
会话1：执行1个SQL
mysql> begin;
Query OK, 0 rows affected (0.00 sec)
mysql> select sleep(20),now() ,id from test1;会话2：开启另一个会话，查看对应的SQL
mysql> select id ,info from information_schema.processlist where info is not null;
+----+------------------------------------------------------------------------------+
| id | info |
+----+------------------------------------------------------------------------------+
| 36 | select sleep(20),now() ,id from test1 |
| 37 | select id ,info from information_schema.processlist where info is not null |
+----+------------------------------------------------------------------------------+
2 rows in set (0.00 sec)可以看到正在执行的SQL，包括自己的SQL的id及内容
1.2 通过events_statements_current查看
会话1：执行1个SQL
mysql> begin;
Query OK, 0 rows affected (0.00 sec)
mysql> select sleep(20),now() ,id from test1;会话2：查看对应的SQL
mysql> select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id\G
*************************** 1. row ***************************
id: 36
info: select sleep(20),now() ,id from test1
thread_id: 76
sql_text: select sleep(20),now() ,id from test1
*************************** 2. row ***************************
id: 37
info: select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id
thread_id: 77
sql_text: select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id
2 rows in set (0.01 sec)2. 方式对比
通过processlist和通过events_statements_current区别在于，processlist中能查到的SQL是正在运行的SQL，而运行结束的SQL是看不到的。
会话1：执行1个SQL
mysql> begin;
Query OK, 0 rows affected (0.00 sec)
mysql> select sleep(2),now() ,id from test1;
+----------+---------------------+----+
| sleep(2) | now() | id |
+----------+---------------------+----+
| 0 | 2023-01-03 22:01:09 | 1 |
+----------+---------------------+----+
1 row in set (2.00 sec)此时查看事务情况
mysql> select * from information_schema.innodb_trx\G
*************************** 1. row ***************************
trx_id: 421227264232664
trx_state: RUNNING
trx_started: 2023-01-03 22:01:09
trx_requested_lock_id: NULL
trx_wait_started: NULL
trx_weight: 0
trx_mysql_thread_id: 36
trx_query: NULL
trx_operation_state: NULL
trx_tables_in_use: 0
trx_tables_locked: 0
trx_lock_structs: 0
trx_lock_memory_bytes: 1128
trx_rows_locked: 0
trx_rows_modified: 0
trx_concurrency_tickets: 0
trx_isolation_level: REPEATABLE READ
trx_unique_checks: 1
trx_foreign_key_checks: 1
trx_last_foreign_key_error: NULL
trx_adaptive_hash_latched: 0
trx_adaptive_hash_timeout: 0
trx_is_read_only: 0
trx_autocommit_non_locking: 0
trx_schedule_weight: NULL
1 row in set (0.00 sec)其中trx_mysql_thread_id=36的会话正是我们会话1的线程id,但是我们看不到具体的SQL
mysql> select * from information_schema.processlist where id=36;
+----+------+-----------+--------+---------+------+-------+------+
| ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO |
+----+------+-----------+--------+---------+------+-------+------+
| 36 | root | localhost | testdb | Sleep | 177 | | NULL |
+----+------+-----------+--------+---------+------+-------+------+
1 row in set (0.00 sec)但是此时通过方式2就可以查到
mysql> select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id\G
*************************** 1. row ***************************
id: 36
info: NULL
thread_id: 76
sql_text: select sleep(2),now() ,id from test1
*************************** 2. row ***************************
id: 37
info: select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id
thread_id: 77
sql_text: select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id
2 rows in set (0.00 sec)注意：此时只能查到一个事务中的多条SQL的最后一个
例如：
mysql> begin;
Query OK, 0 rows affected (0.00 sec)
mysql> select sleep(2),now() ,id from test1;
+----------+---------------------+----+
| sleep(2) | now() | id |
+----------+---------------------+----+
| 0 | 2023-01-03 22:01:09 | 1 |
+----------+---------------------+----+
1 row in set (2.00 sec)
mysql> select sleep(1),now() ,id from test1;
+----------+---------------------+----+
| sleep(1) | now() | id |
+----------+---------------------+----+
| 0 | 2023-01-03 22:06:35 | 1 |
+----------+---------------------+----+会话2查看结果
mysql> select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id\G
*************************** 1. row ***************************
id: 36
info: NULL
thread_id: 76
sql_text: select sleep(1),now() ,id from test1
*************************** 2. row ***************************
id: 37
info: select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id
thread_id: 77
sql_text: select a.id,a.info, b.thread_id, c.sql_text from information_schema.processlist a, performance_schema.threads b, performance_schema.events_statements_current c where a.id=b.processlist_id and b.thread_id = c.thread_id
2 rows in set (0.00 sec)可见，查到的是最后一个SQL了，如果事务手动commit提交了，则显示的是commit
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