Re: [SQL] Vacuum takes more than 1 hr

From: Rich Ryan <postgres(at)weblynk(dot)com>
To: "pgsql-sql(at)postgresql(dot)org" <pgsql-sql(at)postgreSQL(dot)org>
Subject: Re: [SQL] Vacuum takes more than 1 hr
Date: 1999-10-25 15:36:30
Message-ID: 002c01bf1efe$b5e874a0$9befaace@usedcars.com
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Instead of using CVS, will ftp'ing the postgresql.snapshot.tar.gz file do? I
looked around for an explanation of what this file is, but didn't find any.

----- Original Message -----
From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Postgres <postgres(at)weblynk(dot)com>
Cc: pgsql-sql(at)postgresql(dot)org <pgsql-sql(at)postgreSQL(dot)org>
Sent: Monday, October 25, 1999 7:45 AM
Subject: Re: [SQL] Vacuum takes more than 1 hr

> Postgres <postgres(at)weblynk(dot)com> writes:
> > I have a table with about 30 columns and 200K rows. When I perform a
vacuum
> > on it (no analyze) it takes usually a little more than 1 hour.
>
> Hmm, doesn't seem all that large. One question is whether you are all
> the way up-to-date on Postgres --- some performance problems in vacuum
> were fixed recently. (The problems were excessive memory usage,
> actually, but that could translate to long runtime if the process
> started to swap. Does the backend that's doing the vacuum seem to grow
> to a size much larger than it starts at?) I don't recall whether this
> patch is in 6.5.2 or not, but it will be in 6.5.3, or you could pull
> the current REL6_5 branch sources from the CVS server.
>
> A performance problem that still remains is that vacuum seems
> unreasonably slow at updating indexes. Some people have found that
> dropping and recreating indexes around a vacuum nets out faster than
> letting vacuum do it. You should also ask yourself whether each
> index on the table is earning its keep --- each one costs time on
> every insert or update, quite aside from vacuum. Only the indexes
> that actually get used for your common queries are likely to be worth
> their overhead.
>
> regards, tom lane
>
> ************

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