Intermittent Query Performance Issue

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!