Re: inconsistent/weird index usage

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От Hannu Krosing
Тема Re: inconsistent/weird index usage
Дата
Msg-id 1096759241.5508.2.camel@fuji.krosing.net
обсуждение исходный текст
Ответ на Re: inconsistent/weird index usage  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: inconsistent/weird index usage
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On R, 2004-10-01 at 19:34, Tom Lane wrote:
> Josh Berkus <josh@agliodbs.com> writes:
> >> Most of the problem here comes from the fact that "current_date - 7"
> >> isn't reducible to a constant and so the planner is making bad guesses
> >> about how much of each table will be scanned.
>
> > I thought this was fixed in 7.4.  No?
>
> No.  It's not fixed as of CVS tip either, although there was some talk
> of doing something in time for 8.0.

That's weird - my 7.4.2 databases did not consider (now()-'15
min'::interval) to be a constant whereas 7.4.5 does (i.e. it does use
index scan on index on datetime column)

Is this somehow different for date types ?

--------------
Hannu

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