对于postgres wait_event: relation，我如何找到关系?

Question

我试图分离一个分区，但查询总是与relation的wait_event锁定

ALTER TABLE responses_partition DETACH PARTITION part_responses_2016_09;

确定锁定查询的关系的好方法是什么?

Answer 1

我认为确定锁定查询的最简单方法是运行pg_activity工具。它很好地显示了阻塞和等待查询2和3选项卡。

您也可以考虑浏览pg_stat_activity表。

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;

您可以在这里找到更多详细信息:https://wiki.postgresql.org/wiki/Lock_Monitoring