Re: Using index for IS NULL query - Mailing list pgsql-performance

From Andreas Kretschmer
Subject Re: Using index for IS NULL query
Date
Msg-id 20081111205049.GA15899@tux
Whole thread Raw
In response to Re: Using index for IS NULL query  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
Tom Lane <tgl@sss.pgh.pa.us> schrieb:

> "Andrus" <kobruleht2@hot.ee> writes:
> > Index is not used for
> >  is null
>
> > How to fix ?
>
> Update to something newer than 8.1 (specifically, you'll need 8.3).

Right. For my example in the other mail:

test=*# create index idx_foo on foo(i);
CREATE INDEX
test=*# explain analyse select * from foo where i is null;
                                                     QUERY PLAN
--------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on foo  (cost=95.11..4780.49 rows=5000 width=8) (actual time=0.052..0.053 rows=1 loops=1)
   Recheck Cond: (i IS NULL)
   ->  Bitmap Index Scan on idx_foo  (cost=0.00..93.86 rows=5000 width=0) (actual time=0.047..0.047 rows=1 loops=1)
         Index Cond: (i IS NULL)
 Total runtime: 0.076 ms



Andreas
--
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unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
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