【发布时间】：2021-08-04 10:35:56
【问题描述】：
我有一个接收大量数据的端点。它将它插入一个名为 ingress 的表中。我还编写了几个解析器，它们遍历入口表中的消息并将其解析到其他各种表中。
我最近在我们的 postgres 集群上遇到了很多性能问题，我真的找不到原因。所以我首先开始查看pg_stat_activity 表，看看哪些查询需要很长时间。在那里我发现了这个：
postgres=> select pid, query_start, age(clock_timestamp(), query_start) as age, state, wait_event_type, wait_event, LEFT(query, 40)
from pg_stat_activity where state like '%idle%' and datname = 'mydatabase'
order by query_start asc limit 5;
pid | query_start | age | state | wait_event_type | wait_event | left
------+-------------------------------+-----------------+-------+-----------------+------------+------------------------------------------
9429 | 2021-08-04 12:20:55.790618+02 | 00:05:29.874102 | idle | Client | ClientRead | INSERT INTO "ingress_message" ("created_
9551 | 2021-08-04 12:21:42.384146+02 | 00:04:43.280586 | idle | Client | ClientRead | INSERT INTO "ingress_message" ("created_
9776 | 2021-08-04 12:23:37.849208+02 | 00:02:47.815526 | idle | Client | ClientRead | select 1
9922 | 2021-08-04 12:25:02.207894+02 | 00:01:23.456841 | idle | Client | ClientRead | INSERT INTO "ingress_message" ("created_
9891 | 2021-08-04 12:25:02.378745+02 | 00:01:23.285992 | idle | Client | ClientRead | INSERT INTO "ingress_message" ("created_
(5 rows)
如您所见，运行时间最长的查询已运行超过 5 分钟 (!!)，这是由“ClientRead”引起的。这对我来说似乎很奇怪。为什么读取会阻止写入？或者这是否意味着某些进程正在锁定整个表以进行读取？
我检查了 pg_locks 表，它显示了下面的结果。我一直在阅读 pg_locks，但我无法真正理解这些信息告诉我的内容。
我主要想知道的是什么；我可以找出导致插入需要这么长时间的 ClientRead 锁定的查询吗？
postgres=> select * from pg_locks;
locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted | fas
tpath
---------------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+-------+------------------+---------+----
------
relation | 82586 | 11645 | | | | | | | | 93/129 | 3764 | AccessShareLock | t | t
virtualxid | | | | | 93/129 | | | | | 93/129 | 3764 | ExclusiveLock | t | t
relation | 82586 | 22442205 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 9898413 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 9898449 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 12134578 | | | | | | | | 42/6323 | 3141 | AccessShareLock | t | t
relation | 82586 | 12134578 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 12103296 | | | | | | | | 42/6323 | 3141 | AccessShareLock | t | t
relation | 82586 | 12103296 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 12103295 | | | | | | | | 42/6323 | 3141 | AccessShareLock | t | t
relation | 82586 | 12103295 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 12102372 | | | | | | | | 42/6323 | 3141 | AccessShareLock | t | t
relation | 82586 | 12102372 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 12102338 | | | | | | | | 42/6323 | 3141 | AccessShareLock | t | t
relation | 82586 | 12102338 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
relation | 82586 | 12102331 | | | | | | | | 42/6323 | 3141 | AccessShareLock | t | t
relation | 82586 | 12102331 | | | | | | | | 42/6323 | 3141 | RowShareLock | t | t
relation | 82586 | 12102331 | | | | | | | | 42/6323 | 3141 | RowExclusiveLock | t | t
virtualxid | | | | | 42/6323 | | | | | 42/6323 | 3141 | ExclusiveLock | t | t
relation | 19825 | 12429831 | | | | | | | | 31/7218 | 3128 | AccessShareLock | t | t
relation | 19825 | 12429819 | | | | | | | | 31/7218 | 3128 | AccessShareLock | t | t
relation | 19825 | 12429818 | | | | | | | | 31/7218 | 3128 | AccessShareLock | t | t
relation | 19825 | 12429770 | | | | | | | | 31/7218 | 3128 | AccessShareLock | t | t
relation | 19825 | 12429751 | | | | | | | | 31/7218 | 3128 | AccessShareLock | t | t
relation | 19825 | 12429744 | | | | | | | | 31/7218 | 3128 | AccessShareLock | t | t
virtualxid | | | | | 31/7218 | | | | | 31/7218 | 3128 | ExclusiveLock | t | t
relation | 19825 | 12429831 | | | | | | | | 30/6218 | 3127 | AccessShareLock | t | t
relation | 19825 | 12429819 | | | | | | | | 30/6218 | 3127 | AccessShareLock | t | t
relation | 19825 | 12429818 | | | | | | | | 30/6218 | 3127 | AccessShareLock | t | t
relation | 19825 | 12429770 | | | | | | | | 30/6218 | 3127 | AccessShareLock | t | t
relation | 19825 | 12429751 | | | | | | | | 30/6218 | 3127 | AccessShareLock | t | t
relation | 19825 | 12429744 | | | | | | | | 30/6218 | 3127 | AccessShareLock | t | t
virtualxid | | | | | 30/6218 | | | | | 30/6218 | 3127 | ExclusiveLock | t | t
relation | 19825 | 12429831 | | | | | | | | 29/5284 | 3126 | AccessShareLock | t | t
relation | 19825 | 12429819 | | | | | | | | 29/5284 | 3126 | AccessShareLock | t | t
relation | 19825 | 12429818 | | | | | | | | 29/5284 | 3126 | AccessShareLock | t | t
relation | 19825 | 12429770 | | | | | | | | 29/5284 | 3126 | AccessShareLock | t | t
relation | 19825 | 12429751 | | | | | | | | 29/5284 | 3126 | AccessShareLock | t | t
relation | 19825 | 12429744 | | | | | | | | 29/5284 | 3126 | AccessShareLock | t | t
virtualxid | | | | | 29/5284 | | | | | 29/5284 | 3126 | ExclusiveLock | t | t
relation | 19825 | 12429831 | | | | | | | | 28/5964 | 3123 | AccessShareLock | t | t
relation | 19825 | 12429819 | | | | | | | | 28/5964 | 3123 | AccessShareLock | t | t
relation | 19825 | 12429818 | | | | | | | | 28/5964 | 3123 | AccessShareLock | t | t
relation | 19825 | 12429770 | | | | | | | | 28/5964 | 3123 | AccessShareLock | t | t
relation | 19825 | 12429751 | | | | | | | | 28/5964 | 3123 | AccessShareLock | t | t
relation | 19825 | 12429744 | | | | | | | | 28/5964 | 3123 | AccessShareLock | t | t
virtualxid | | | | | 28/5964 | | | | | 28/5964 | 3123 | ExclusiveLock | t | t
relation | 29251 | 31001 | | | | | | | | 71/415 | 10820 | AccessShareLock | t | t
relation | 29251 | 30988 | | | | | | | | 71/415 | 10820 | AccessShareLock | t | t
relation | 29251 | 30981 | | | | | | | | 71/415 | 10820 | AccessShareLock | t | t
virtualxid | | | | | 71/415 | | | | | 71/415 | 10820 | ExclusiveLock | t | t
relation | 29251 | 30981 | | | | | | | | 72/645 | 10821 | AccessShareLock | t | t
virtualxid | | | | | 72/645 | | | | | 72/645 | 10821 | ExclusiveLock | t | t
transactionid | | | | | | 1762434479 | | | | 42/6323 | 3141 | ExclusiveLock | t | f
(54 rows)
【问题讨论】：
标签： postgresql performance locking pg stat