mysql 的慢查询日志里有 commit 语句，是怎么回事？ google 了半天也没找到相关信息。

User@Host: tester[tester] @ [192.168.2.38]

Thread_id: 171 Schema: dddder QC_hit: No

Query_time: 0.524212 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0

SET timestamp=1515512553; commit;

User@Host: tester[tester] @ [192.168.2.38]

Thread_id: 17 Schema: dddder QC_hit: No

Query_time: 0.522975 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0

SET timestamp=1515512553; commit;

User@Host: tester[tester] @ [192.168.2.38]

Thread_id: 331 Schema: dddder QC_hit: No

Query_time: 0.510277 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0

SET timestamp=1515512553; commit;