MySQL如何找出未提交事務信息

前陣子，我寫了一篇博客「ORACLE中可否找到未提交事務的SQL語句」， 那麼在MySQL數據庫中，咱們可否找出未提交事務執行的SQL語句或未提交事務的相關信息呢？

 

實驗驗證了一下，若是一個會話(鏈接)裏面有一個未提交事務，而後不作任何操做，那麼這個線程處於Sleep狀態

 

mysql> select connection_id() from dual;

+-----------------+

| connection_id() |

+-----------------+

|               6 |

+-----------------+

1 row in set (0.00 sec)

mysql> set session autocommit=0;

Query OK, 0 rows affected (0.00 sec)

mysql> delete from kkk where id =1;

Query OK, 1 row affected (0.00 sec)

mysql> 

 

 

在另一個會話（鏈接）裏面，查詢這個超過10秒未提交事務的詳細信息：

 

SELECT t.trx_mysql_thread_id

      ,t.trx_state

      ,t.trx_tables_in_use

      ,t.trx_tables_locked

      ,t.trx_query

      ,t.trx_rows_locked 

      ,t.trx_rows_modified

      ,t.trx_lock_structs

      ,t.trx_started

      ,t.trx_isolation_level

      ,p.time 

      ,p.user

      ,p.host

      ,p.db

      ,p.command

FROM   information_schema.innodb_trx t 

       INNER JOIN information_schema.processlist p 

               ON t.trx_mysql_thread_id = p.id 

WHERE  t.trx_state = 'RUNNING' 

       AND p.time > 10 

       AND p.command = 'Sleep'\G 

 

 

 

 

如上截圖所示，trx_query 爲NULL值。基本上沒法找到未提交事務的SQL語句，MySQL內部關於事務的信息不是很細，甚至能夠說有點簡潔。我甚至沒法定位到在那個表上發生了鎖。只能看到trx_row_locked、trx_row_modified、trx_started等信息。使用show engine innodb status也是如此，只能看到一些基本信息

 

mysql> show engine innodb status;

 

 

---TRANSACTION 1282583, ACTIVE 11937 sec

2 lock struct(s), heap size 360, 8 row lock(s), undo log entries 1

MySQL thread id 6, OS thread handle 0x7f8da2de3700, query id 190 localhost root

 

若是未提交的事務，阻塞了其它會話，那麼有可能（僅僅是存在可能性，不少場景也不能找到位提交事務的相關SQL）找到未提交事務執行的SQL

 

以下測試所示，會話（鏈接 connection_id=11）中執行了delete操做，可是未提交事務

 

mysql> set session autocommit=0;

Query OK, 0 rows affected (0.00 sec)

mysql> select connection_id();

+-----------------+

| connection_id() |

+-----------------+

|              11 |

+-----------------+

1 row in set (0.01 sec)

mysql> delete from kkk where id=1;

Query OK, 1 row affected (0.00 sec)

mysql> 

 

另一個會話（鏈接）執行了一個更新記錄的操做。此時SQL將被阻塞。

 

mysql> select connection_id();

+-----------------+

| connection_id() |

+-----------------+

|              13 |

+-----------------+

1 row in set (0.00 sec)

mysql> 

mysql> update kkk set id=100 where id=1;

 

咱們在另外的會話中，執行下面SQL就能夠查到未提交事務最後執行的SQL。

 

mysql> SELECT r.trx_id              waiting_trx_id, 

    ->        r.trx_mysql_thread_id waiting_thread, 

    ->        r.trx_query           waiting_query, 

    ->        b.trx_id              blocking_trx_id, 

    ->        b.trx_mysql_thread_id blocking_thread, 

    ->        b.trx_query           blocking_query 

    -> FROM   information_schema.innodb_lock_waits w 

    ->        INNER JOIN information_schema.innodb_trx b 

    ->                ON b.trx_id = w.blocking_trx_id 

    ->        INNER JOIN information_schema.innodb_trx r 

    ->                ON r.trx_id = w.requesting_trx_id; 

+----------------+----------------+----------------------------------+-----------------+-----------------+----------------+

| waiting_trx_id | waiting_thread | waiting_query                    | blocking_trx_id | blocking_thread | blocking_query |

+----------------+----------------+----------------------------------+-----------------+-----------------+----------------+

| 2830           |             13 | update kkk set id=100 where id=1 | 2825            |              11 | NULL           |

+----------------+----------------+----------------------------------+-----------------+-----------------+----------------+

1 row in set (0.00 sec)

mysql> SELECT a.sql_text, 

    ->        c.id, 

    ->        d.trx_started 

    -> FROM   performance_schema.events_statements_current a 

    ->        join performance_schema.threads b 

    ->          ON a.thread_id = b.thread_id 

    ->        join information_schema.processlist c 

    ->          ON b.processlist_id = c.id 

    ->        join information_schema.innodb_trx d 

    ->          ON c.id = d.trx_mysql_thread_id 

    -> where c.id=11

    -> ORDER  BY d.trx_started\G;

*************************** 1. row ***************************

   sql_text: delete from kkk where id =1

         id: 11

trx_started: 2019-06-12 23:36:13

1 row in set (0.03 sec)

ERROR: 

No query specified

mysql> 

 

 

 

 

總結：基本上MySQL只能找到未提交事務的基本信息，例如trx_mysql_thread_id等。某些場景下，咱們幾乎沒有方法找出未提交事務執行的SQL等詳細信息。搞不清未提交事務作了什麼操做！