Re: Index usage problem on 8.3.3

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jeff Frost <jeff(at)frostconsultingllc(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Index usage problem on 8.3.3
Date: 2008-10-31 01:27:58
Message-ID: 14766.1225416478@sss.pgh.pa.us
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Jeff Frost <jeff(at)frostconsultingllc(dot)com> writes:
> Tom Lane wrote:
>> Okay. What that means is that the indexes were created on data that had
>> already been inserted and updated to some extent, resulting in
>> HOT-update chains that turned out to be illegal for the new indexes.
>> The way we deal with this is to mark the indexes as not usable by any
>> query that can still see the dead HOT-updated tuples.

> Any idea why I don't see it on 8.3.4?

I think it's more likely some small difference in your test conditions
than any real version-to-version difference. In particular I think the
"still see" test might be influenced by the ages of transactions running
concurrently.

regards, tom lane

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