From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
Cc: | Sergey Burladyan <eshkinkot(at)gmail(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Looks like merge join planning time is too big, 55 seconds |
Date: | 2013-08-02 15:50:48 |
Message-ID: | 1899.1375458648@sss.pgh.pa.us |
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Lists: | pgsql-performance |
Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> On Thu, Aug 1, 2013 at 5:16 PM, Sergey Burladyan <eshkinkot(at)gmail(dot)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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