To: Ron St-Pierre <ron.pgsql@shaw.ca>
cc: pgsql-performance@postgresql.org
Subject: Re: 12 hour table vacuums 
In-reply-to: <471E18ED.3090704@shaw.ca> 
References: <471E18ED.3090704@shaw.ca>
Comments: In-reply-to Ron St-Pierre <ron.pgsql@shaw.ca>
	message dated "Tue, 23 Oct 2007 08:53:17 -0700"
Date: Tue, 23 Oct 2007 12:11:51 -0400
Message-ID: <19338.1193155911@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Ron St-Pierre <ron.pgsql@shaw.ca> writes:
> The table has 140,000 rows, 130 columns (mostly NUMERIC), 60 indexes. It 
> is probably our 'key' table in the database and gets called by almost 
> every query (usually joined to others). The table gets updated only 
> about 10 times a day. We were running autovacuum but it interfered with 
> the updates to we shut it off. We vacuum this table nightly, and it 
> currently takes about 12 hours to vacuum it. Not much else is running 
> during this period, nothing that should affect the table.

Here is your problem:

> vacuum_cost_delay = 200

If you are only vacuuming when nothing else is happening, you shouldn't
be using vacuum_cost_delay at all: set it to 0.  In any case this value
is probably much too high.  I would imagine that if you watch the
machine while the vacuum is running you'll find both CPU and I/O load
near zero ... which is nice, unless you would like the vacuum to finish
sooner.

In unrelated comments:

> maintenance_work_mem = 786432

That seems awfully high, too.

> max_fsm_pages = 70000

And this possibly too low --- are you sure you are not leaking disk
space?

> stats_start_collector = off
> stats_command_string = on
> stats_block_level = on
> stats_row_level = on    

These are not self-consistent.

			regards, tom lane