From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Monnerie <michael.monnerie@is.it-management.at>
Cc: pgsql-admin@postgresql.org
Subject: Re: Optimizing Update with WHERE x IN (id1,id2,...)
Date: Wed, 22 Dec 2010 10:23:27 -0500
Message-ID: <5294.1293031407@sss.pgh.pa.us> (raw)
In-Reply-To: <201012221059.38145@zmi.at>
References: <201012221059.38145@zmi.at>
Michael Monnerie <michael.monnerie@is.it-management.at> writes:
> I just saw this EXPLAIN in PostgreSQL 8.3.12:
> [ just like any other bitmap index scan ]
> And it seems to me that could be optimized to skip the "Recheck Cond" as
> that is already checked by the Index Scan? Should save some CPU cycles.
You evidently don't understand what that's for. In typical cases it's
not rechecked. The recheck condition is only applied if the index scan
becomes lossy.
regards, tom lane
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To: pgsql-admin@postgresql.org
Cc: tgl@sss.pgh.pa.us, michael.monnerie@is.it-management.at
Subject: Re: Optimizing Update with WHERE x IN (id1,id2,...)
In-Reply-To: <5294.1293031407@sss.pgh.pa.us>
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