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List:       postgresql-general
Subject:    Re: [GENERAL] B-tree performance improvements in 8.x
From:       Dick Kniep <dick () kniep ! nl>
Date:       2006-02-08 17:02:08
Message-ID: 200602081802.08597.dick () kniep ! nl
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On Wednesday 08 February 2006 06:18, Tom Lane wrote:
> Dick Kniep <dick@kniep.nl> writes:
> > Does this also affect if you have many NULL values in the key? So testing
> > Not is NULL would also be affected?
>
> IS NOT NULL isn't an indexable operation, so your question doesn't really
> apply :-(

Does this mean that if you have a table that has many rows, and 95% of the 
rows contain a NULL value for a field, that indexing will be useless, because 
it will always do a tablescan?

Hope not!

Dick

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