From: Pavel Stehule [mailto:pavel.steh...@gmail.com] 
Sent: Thursday, June 19, 2014 3:28 PM
To: Huang, Suya
Cc: pgsql-performance@postgresql.org
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.hu...@au.experian.com>:
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


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