From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Janes <jeff.janes@gmail.com>
cc: Sergey Burladyan <eshkinkot@gmail.com>,
 "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Looks like merge join planning time is too big, 55 seconds
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Comments: In-reply-to Jeff Janes <jeff.janes@gmail.com>
 message dated "Fri, 02 Aug 2013 08:29:34 -0700"
Date: Fri, 02 Aug 2013 11:50:48 -0400
Message-ID: <1899.1375458648@sss.pgh.pa.us>
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Sender: pgsql-performance-owner@postgresql.org

Jeff Janes <jeff.janes@gmail.com> writes:
> On Thu, Aug 1, 2013 at 5:16 PM, Sergey Burladyan <eshkinkot@gmail.com> wrote:
>> If I not mistaken, may be two code paths like this here:
>> (1) mergejoinscansel -> scalarineqsel-> ineq_histogram_selectivity -> get_actual_variable_range -> index_getnext
>> (2) scalargtsel -> scalarineqsel -> ineq_histogram_selectivity -> get_actual_variable_range -> index_getnext

> Yeah, I think you are correct.

mergejoinscansel does *not* call scalarineqsel, nor get_actual_variable_range.
It calls get_variable_range, which only looks at the pg_statistic entries.

I think we need to see the actual stack traces, not incomplete versions.
It's possible that the situation here involves bloat in pg_statistic, but
we're just leaping to conclusions if we assume that that's where the index
fetches are occurring.

			regards, tom lane


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