From: Pavel Stehule [mailto:pavel.stehule@xxxxxxxxx] Sent: Thursday, June 19, 2014 3:28 PM To: Huang, Suya Cc: pgsql-performance@xxxxxxxxxxxxxx Subject: Re: [PERFORM] huge pgstat.stat file on PostgreSQL 8.3.24 Hello The size of statfile is related to size of database objects in database. Depends on PostgreSQL version this file can be one per database cluster or one per database (from 9.3), These statistics should by reset by call pg_stat_reset() http://www.postgresql.org/docs/9.2/static/monitoring-stats.html Autovacuum on large stat files has significant overhead - it can be increasing by using new PostgreSQL (9.3) and by migration stat directory to ramdisk - by setting stats_temp_directory to some dir on ramdisk (tmpfs on Linux) Regards Pavel 2014-06-19 6:38 GMT+02:00 Huang, Suya <Suya.Huang@xxxxxxxxxxxxxxx>: Hi group, We’ve found huge pgstat.stat file on our production DB boxes, the size is over 100MB. autovacuum is enabled. So my question would be: 1. What’s a reasonable size of pgstat.stat file, can it be estimated? 2. What’s the safest way to reduce the file size to alleviate the IO impact on disk? 3. If need to drop all statistics, would a “analyze DB” command enough to eliminate the performance impact on queries? Thanks, Suya Hi Pavel, our version is 8.3.24, not 9.3. I also want to know the impact caused by run pg_stat_reset to application, is that able to be mitigated by doing an analyze database command? Thanks, Suya
