From: Tom Lane <tgl@sss.pgh.pa.us>
To: marko@joh.to
Cc: pgsql-bugs@postgresql.org
Subject: Re: BUG #11500: PRIMARY KEY index not being used
Date: Fri, 26 Sep 2014 13:44:39 -0400
Message-ID: <8043.1411753479@sss.pgh.pa.us> (raw)
In-Reply-To: <20140926080211.7639.68358@wrigleys.postgresql.org>
References: <20140926080211.7639.68358@wrigleys.postgresql.org>
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marko@joh.to writes:
> PostgreSQL version: 9.1.12
> We've been observing a performance problem where a PRIMARY KEY index is not
> being used. The problem looks like this:
In 9.2 and again in 9.3, we significantly changed the planner's modeling
of index access costs, with a view towards making better choices when
there are multiple plausible indexes to use. If you can reproduce this
misbehavior in 9.3 or later it would be worth looking into; but we're not
going to change 9.1's estimation rules at this late date. People running
on back branches tend to want plan stability in my experience.
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, marko@joh.to
Subject: Re: BUG #11500: PRIMARY KEY index not being used
In-Reply-To: <8043.1411753479@sss.pgh.pa.us>
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