From: David Barton <dave@oneit.com.au>
To: pgsql-performance@postgresql.org
Subject: Postgres 9.1.4 - high stats collector IO usage
Date: Sat, 28 Jul 2012 12:33:17 +0800
Message-ID: <50136B8D.7070502@oneit.com.au> (raw)
Hi,
I am running postgres 9.1.4 on Ubuntu 12.04 and the stats collector is
generating very high IO usage even when nothing appears to be happening
on the system.
I have roughly 150 different databases, each of which is running in 1 of
roughly 30 tablespaces. The databases are small (the dump of most is
are under 100M, and all but 3 are under 1G, nothing larger than 2G).
Previously iotop reported the disk write speed, at ~6MB / second. I
went and reset the stats for every database and that shrunk the stats
file and brought the IO it down to 1MB / second. I still think this is
too high for an idle database. I've now noticed it is growing.
ls -l /var/lib/postgresql/9.1/main/pg_stat_tmp/pgstat.stat
-rw------- 1 postgres postgres 3515080 Jul 28 11:58
/var/lib/postgresql/9.1/main/pg_stat_tmp/pgstat.stat
*<reset of stats> *
ls -l /var/lib/postgresql/9.1/main/pg_stat_tmp/pgstat.stat
-rw------- 1 postgres postgres 514761 Jul 28 12:11
/var/lib/postgresql/9.1/main/pg_stat_tmp/pgstat.stat
*<watch the file grow>*
ls -l /var/lib/postgresql/9.1/main/pg_stat_tmp/pgstat.stat
-rw------- 1 postgres postgres 776711 Jul 28 12:25
/var/lib/postgresql/9.1/main/pg_stat_tmp/pgstat.stat
In the 15 minutes since the reset, IO has nearly doubled to 1.6+ MB /
second.
FWIW, I just migrated all these databases over to this new server by
restoring from pg_dump I was previously experiencing this on 8.3, which
was why I upgraded to 9.1 and I also have another server with similar
problems on 9.1.
Any help would be sincerely appreciated.
David Barton dave@oneit.com.au
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To: pgsql-performance@postgresql.org
Cc: dave@oneit.com.au
Subject: Re: Postgres 9.1.4 - high stats collector IO usage
In-Reply-To: <50136B8D.7070502@oneit.com.au>
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