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Re: When to do a vacuum for highly active table

From: Chris Browne <cbbrowne(at)acm(dot)org>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: When to do a vacuum for highly active table
Date: 2005-08-30 22:05:38
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
thing(at)m-bass(dot)com (Markus Benne) writes:
> We have a highly active table that has virtually all
> entries updated every 5 minutes.  Typical size of the
> table is 50,000 entries, and entries have grown fat.
> We are currently vaccuming hourly, and towards the end
> of the hour we are seeing degradation, when compared
> to the top of the hour.

You're not vacuuming the table nearly often enough.

You should vacuum this table every five minutes, and possibly more
often than that.

[We have some tables like that, albeit smaller than 50K entries, which
we vacuum once per minute in production...]

> We are thinking of splitting the table in two: the part the updates
> often, and the part the updates infrequently as we suspect that
> record size impacts vacuum.

There's *some* merit to that.

You might discover that there's a "hot spot" that needs to be vacuumed
once per minute.

But it may be simpler to just hit the table with a vacuum once every
few minutes even though some tuples are seldom updated.
output = reverse("gro.gultn" "@" "enworbbc")
Signs  of  a  Klingon  Programmer #3:  "By   filing this  TPR you have
challenged the honor of my family. Prepare to die!"

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Subject: 'Real' auto vacuum?
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