From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: Kris Jurka <books@ejurka.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: No hash join across partitioned tables?
Date: Wed, 09 Jun 2010 16:11:25 -0400
Message-ID: <489.1276114285@sss.pgh.pa.us> (raw)
In-Reply-To: <AANLkTinx8lLTEKWcyEQ1rxVz6WMJVKNezfXW5TKnNAU6@mail.gmail.com>
References: <201002252346.o1PNkXG07892@momjian.us>
<9477.1267142614@sss.pgh.pa.us>
<603c8f071003020816j77b3ec63wbad0415df003c0f1@mail.gmail.com>
<17546.1267546998@sss.pgh.pa.us>
<AANLkTinx8lLTEKWcyEQ1rxVz6WMJVKNezfXW5TKnNAU6@mail.gmail.com>
Robert Haas <robertmhaas@gmail.com> writes:
> In going back through emails I had marked as possibly needing another
> look before 9.0 is released, I came across this issue again. As I
> understand it, analyze (or analyse) now collects statistics for both
> the parent individually, and for the parent and its children together.
> However, as I further understand it, autovacuum won't actually fire
> off an analyze unless there's enough activity on the parent table
> considered individually to warrant it. So if you have an empty parent
> and a bunch of children with data in it, your stats will still stink,
> unless you analyze by hand.
Check.
> Assuming my understanding of the problem is correct, we could:
> (a) fix it,
> (b) document that you should consider periodic manual analyze commands
> in this situation, or
> (c) do nothing.
> Thoughts?
The objections to (a) are that it might result in excessive ANALYZE work
if not done intelligently, and that we haven't got a patch ready anyway.
I would have liked to get to this for 9.0 but I feel it's a bit late
now.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, robertmhaas@gmail.com, bruce@momjian.us, books@ejurka.com
Subject: Re: No hash join across partitioned tables?
In-Reply-To: <489.1276114285@sss.pgh.pa.us>
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