From: Michael Monnerie <michael.monnerie@is.it-management.at>
To: pgsql-admin@postgresql.org
Subject: Re: Question on Index usage
Date: Wed, 21 Jan 2009 16:32:41 +0100
Message-ID: <200901211632.41348@zmi.at> (raw)
In-Reply-To: <2116.1232551538@sss.pgh.pa.us>
References: <200901210854.28091@zmi.at>
<20090121142829.GE4038@alvh.no-ip.org>
<2116.1232551538@sss.pgh.pa.us>
On Mittwoch 21 Januar 2009 Tom Lane wrote:
> No, AFAIR the planner will *always* include every possibly relevant
> condition for a given index. If the condition is useless or nearly
> so, that might prompt it to pick a different index instead, but not
> to omit the indexqual. I'm thinking it's not believing it can use
> the status condition with that index, perhaps for datatype reasons.
> What is status declared as, exactly?
OK, now I'm sure you're speaking in a direction I didn't mean ;-)
But still, it could use the index _7 for the status field, as that's
sorted and 0,1,2 would be all together.
status | smallint | not null default (0)::smallint
Maybe it doesn't do because it could well be 0,1,3 also, and it's not
checking if all the values in the IN() statement appear in a row?
> Also, what PG version is this?
8.3 on openSUSE 11.1: select version();
PostgreSQL 8.3.5 on x86_64-unknown-linux-gnu, compiled by GCC gcc (SUSE
Linux) 4.3.2 [gcc-4_3-branch revision 141291]
mfg zmi
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To: pgsql-admin@postgresql.org
Cc: michael.monnerie@is.it-management.at
Subject: Re: Question on Index usage
In-Reply-To: <200901211632.41348@zmi.at>
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