Re: many 'OR' in WHERE-condition

am Fri, dem 20.04.2007, um 12:03:44 +0100 mailte Richard Huxton folgendes:
> A. Kretschmer wrote:
> >in a SELECT with a condition 'WHERE foo IN (1,2,3,4,...)' with a large
> ...
> >But if the list increase the planner choose an seq-scan. The amount of
> >values in the list is about 200 and the table has about 250.000 rows.
> >
> >How can we avoid the seq-scan?
>
> Are you sure you'd want to? What plan have you found to be faster with
> 200 tests?

It's not my problem - i found it in a forum (german)
http://pg-forum.de/showthread.php?t=1332

If the list contains up to 195 entrys -> up to 195 bitmap index scans
and BitmapOr -> 7.839ms

If the list contains 196 entrys -> seq-scan -> 5591.567ms

Andreas
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Andreas Kretschmer
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