From: | Murthy Nunna <mnunna(at)fnal(dot)gov> |
---|---|
To: | "pgsql-admin(at)postgresql(dot)org" <pgsql-admin(at)postgresql(dot)org> |
Subject: | Intermittent Query Performance Issue |
Date: | 2024-04-19 17:02:41 |
Message-ID: | DM8PR09MB66772143CBEAD3538AB98906B80D2@DM8PR09MB6677.namprd09.prod.outlook.com |
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Lists: | pgsql-admin |
Hi,
I am running pg 14.4
I have a simple query :
select max(c) from tab1 where name = 'xxx' ;
This query runs some times very slow. It takes about 40 minutes.
Most of the time it completes in few seconds.
When it runs slow, wait_event in pg_stat_activity shows "DataFileRead". Obviously, it is reading from file storage and that is why it is taking so long.
This is a big table 512GB. It has some child tables.
Is there a way I can reproduce the slowness at will, so I can attempt to tune it? Or any ideas I can try to fix the issue? I hate to try something not knowing if the problem is fixed or not. That is the reason I would like to reproduce the issue first.
Thank you all!
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