Re: 8.x index insert performance

From: "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>
To: <mark(at)mark(dot)mielke(dot)cc>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: 8.x index insert performance
Date: 2005-10-31 20:27:31
Message-ID: 6EE64EF3AB31D5448D0007DD34EEB3417DD730@Herge.rcsinc.local
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> On Mon, Oct 31, 2005 at 12:32:03PM -0500, Merlin Moncure wrote:
> > if that index is causing the problem, you may want to consider
setting
> > up partial index to exclude null values.
>
> Hey all.
>
> Pardon my ignorance. :-)
>
> I've been trying to figure out whether null values are indexed or not
from
> the documentation. I was under the impression, that null values are
not
> stored in the index. Occassionally, though, I then see a suggestion
such
> as the above, that seems to indicate to me that null values *are*
stored
> in the index, allowing for the 'exclude null values' to have effect?
>
> Which is it? :-)

I think I'm the ignorant one...do explain on any lookup on an indexed
field where the field value is null and you get a seqscan.

Merlin

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