Re: Index on a NULL-value

From: Tobias Brox
Subject: Re: Index on a NULL-value
Date: ,
Msg-id: 20050601054251.GT26100@tobias.exoweb.net
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In response to: Index on a NULL-value  (Tobias Brox)
List: pgsql-performance

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Index on a NULL-value  (Tobias Brox, )
 Re: Index on a NULL-value  (Bruno Wolff III, )
  Re: Index on a NULL-value  (Tobias Brox, )
   Re: Index on a NULL-value  (Bruno Wolff III, )
 Re: Index on a NULL-value  (Tobias Brox, )
  Re: Index on a NULL-value  (Bruno Wolff III, )
   Re: Index on a NULL-value  (Tobias Brox, )
    Re: Index on a NULL-value  (Greg Stark, )
     Re: Index on a NULL-value  (Tom Lane, )
   Re: Index on a NULL-value  (Tom Lane, )
    Re: Index on a NULL-value  (Tobias Brox, )
 Re: Index on a NULL-value  (Tobias Brox, )

[Tobias Brox - Tue at 11:02:07AM +0800]
> I read in the manual today:
>
>   Indexes are not used for IS NULL clauses by default. The best way to use
>   indexes in such cases is to create a partial index using an IS NULL
>   predicate.

I have summarized this thread in a postgresql doc user comment, posted at
http://www.postgresql.org/docs/current/interactive/sql-createindex.html

I think it's a good thing to do, since it can be difficult to search the
mailing list archives :-)

--
Tobias Brox, Beijing


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