Re: Strange postgres planner behaviour

On Sat, 12 Mar 2005, Tom Lane wrote:

> "Sergey E. Koposov" <math(at)sai(dot)msu(dot)ru> writes:
>> I want to descibe some strange behaviour of the postgres planner.
>
> It's not strange exactly: the mechanism for OR indexscan and the
> mechanism for nestloop join indexscan are separate and don't talk
> to each other. So you don't get to have a join inner indexscan that
> involves an OR condition.
>
> I have some vague ideas about replacing orindxpath.c entirely, once
> we have some infrastructure for doing OR indexscans via bitmap union.
> But it's not just around the corner.

for 8.1, probably ?

>
> In the meantime you might try expressing your query as a UNION.

Hmm, I'm wondering if the table will be reades as much as the number
of UNIONs or there is some optimization ?

>
> regards, tom lane
>
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Regards,
Oleg
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Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
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