使用 TypeOrm 执行原始 PostgreSQL 查询时挂起答案

【问题标题】：A raw PostgreSQL query hangs when executed with TypeOrm使用 TypeOrm 执行原始 PostgreSQL 查询时挂起
【发布时间】：2020-12-08 04:51:40
【问题描述】：

我正在做这个更新查询：

await this.userRepository.query(
    `
        update "user" u
        set profile_pic = i.name
        from user_images_image uii
        inner join image i on uii."imageId" = i."id"
        where uii."userId" = u.id and u.id = ${userId} and i.id = ${imageId};
    `,
);

即使我在我的数据库客户端中执行相同的查询并且它按预期工作，它也不会终止。

【问题讨论】：

pg_stat_activity 在说什么？连接状态如何？
@GustavoKawamoto pg_stat_activity 表示这是一个锁，即wait_event_type 是锁，wait_event 是 transactionid，state 是活动的。你问的是连接状态吗？
是的。从表面上看，有些东西以某种方式锁定了您的更新。您可以使用 these queries 找到锁定的内容。
@GustavoKawamoto 哦，谢谢，我会去看看。但正如我刚刚设法发现它与我正在进行的交易有关，更准确地说，我已经重写了相同的方法而不进行交易并且它有效......
@GustavoKawamoto 你对这个transactionid 可能有什么想法吗？我不太清楚它是如何在低级别工作的。

标签： node.js postgresql sql-update typeorm

【解决方案1】：

在进行故障排除会话后，我们发现查询已被锁定，因为另一个连接试图更新相关资源（users 表中的一条记录，外键来自 user_images_image）相同的方法，都在等待提交结果。

通过使用相同的连接，我们最终得到了正确的行为。

我们通过锁定监控查询from the docs发现了这一点：

SELECT blocked_locks.pid     AS blocked_pid,
         blocked_activity.usename  AS blocked_user,
         blocking_locks.pid     AS blocking_pid,
         blocking_activity.usename AS blocking_user,
         blocked_activity.query    AS blocked_statement,
         blocking_activity.query   AS current_statement_in_blocking_process,
         blocked_activity.application_name AS blocked_application,
         blocking_activity.application_name AS blocking_application
   FROM  pg_catalog.pg_locks         blocked_locks
    JOIN pg_catalog.pg_stat_activity blocked_activity  ON blocked_activity.pid = blocked_locks.pid
    JOIN pg_catalog.pg_locks         blocking_locks 
        ON blocking_locks.locktype = blocked_locks.locktype
        AND blocking_locks.DATABASE IS NOT DISTINCT FROM blocked_locks.DATABASE
        AND blocking_locks.relation IS NOT DISTINCT FROM blocked_locks.relation
        AND blocking_locks.page IS NOT DISTINCT FROM blocked_locks.page
        AND blocking_locks.tuple IS NOT DISTINCT FROM blocked_locks.tuple
        AND blocking_locks.virtualxid IS NOT DISTINCT FROM blocked_locks.virtualxid
        AND blocking_locks.transactionid IS NOT DISTINCT FROM blocked_locks.transactionid
        AND blocking_locks.classid IS NOT DISTINCT FROM blocked_locks.classid
        AND blocking_locks.objid IS NOT DISTINCT FROM blocked_locks.objid
        AND blocking_locks.objsubid IS NOT DISTINCT FROM blocked_locks.objsubid
        AND blocking_locks.pid != blocked_locks.pid
 
    JOIN pg_catalog.pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid
   WHERE NOT blocked_locks.GRANTED;

【讨论】：