更新时间:2022-08-16 GMT+08:00

分析作业是否被阻塞

数据库系统运行时,在某些业务场景下查询语句会被阻塞,导致语句运行时间过长,可以强制结束有问题的会话。

操作步骤

  1. 查看阻塞的查询语句及阻塞查询的表、模式信息。

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    SELECT w.query as waiting_query,
    w.pid as w_pid,
    w.usename as w_user,
    l.query as locking_query,
    l.pid as l_pid,
    l.usename as l_user,
    t.schemaname || '.' || t.relname as tablename
    from pg_stat_activity w join pg_locks l1 on w.pid = l1.pid
    and not l1.granted join pg_locks l2 on l1.relation = l2.relation
    and l2.granted join pg_stat_activity l on l2.pid = l.pid join pg_stat_user_tables t on l1.relation = t.relid
    where w.waiting;
    

    该查询返回线程ID、用户信息、查询状态,以及导致阻塞的表、模式信息。

  2. 使用如下命令结束相应的会话。其中,139834762094352为线程ID。

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    SELECT PG_TERMINATE_BACKEND(139834762094352);
    

    显示类似如下信息,表示结束会话成功。

     PG_TERMINATE_BACKEND
    ----------------------
     t
    (1 row)

    显示类似如下信息,表示用户正在尝试结束当前会话,此时仅会重连会话,而不是结束会话。

    FATAL:  terminating connection due to administrator command
    FATAL:  terminating connection due to administrator command
    The connection to the server was lost. Attempting reset: Succeeded.

    gsql客户端使用PG_TERMINATE_BACKEND函数终止本会话后台线程时,客户端不会退出而是自动重连。