From: | Wes <wespvp(at)syntegra(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Wes <wespvp(at)syntegra(dot)com> |
Cc: | Postgresql-General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Vacuum time degrading |
Date: | 2005-04-05 16:08:25 |
Message-ID: | BE782229.A01D%wespvp@syntegra.com |
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Lists: | pgsql-general pgsql-hackers |
On 4/4/05 8:50 AM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> That doesn't follow from what you said. Did you check that the physical
> sizes of the indexes were comparable before and after the reindex?
No, how do I do that (or where is it documented how to do it)?
How is it not consistent? I believe you suggested the reindex. The initial
timing was shortly after a database reload. The index would have been built
in sorted order, correct? This was the 1 hour time. After a period of
months, the index values have been inserted in random order. The DB size is
up 50% but the vacuum time is up a factor of 6+. Presumably the index is
being read by moving the heads all over the place. I reindex, and the index
is rebuilt in sorted order. Vacuum is now down to 1.5 hours - a linear
scaling from the original numbers. The locality of reference in reading the
indexes in order should be much better.
Wes
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