Re: Using index for IS NULL query

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Tom Lane <tgl@xxxxxxxxxxxxx> schrieb:

> "Andrus" <kobruleht2@xxxxxx> 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
-- 
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

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