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Re: Optimizer Selecting Incorrect Index - Mailing list pgsql-performance

From Tom Lane
Subject Re: Optimizer Selecting Incorrect Index
Date
Msg-id 2137.1093460881@sss.pgh.pa.us
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In response to Re: Optimizer Selecting Incorrect Index  (Richard Huxton <dev@archonet.com>)
Responses Re: Optimizer Selecting Incorrect Index  ("David Price" <dprice@dentfirst.com>)
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Richard Huxton <dev@archonet.com> writes:
> Things to check:
> 1. postgresql.conf settings match - different costs could cause this
> 2. statistics on the two columns (trn_patno,trn_old_date) - if they
> differ considerably between systems that would also explain it.

The different estimated row counts could only come from #2.  I suspect
David has forgotten to run ANALYZE on the second system.

I agree that EXPLAIN VERBOSE output is not helpful...

            regards, tom lane

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