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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ron Mayer <rm_pg@cheapcomplexdevices.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Missed index opportunity for outer join?
Date: Tue, 06 Dec 2005 16:24:59 -0500
Message-ID: <16502.1133904299@sss.pgh.pa.us> (raw)
In-Reply-To: <4395FF61.6060301@cheapcomplexdevices.com>
References: <Pine.LNX.4.58.0512051401090.21335@greenie.cheapcomplexdevices.com>
	<3267.1133822299@sss.pgh.pa.us>
	<Pine.LNX.4.58.0512051443130.21474@greenie.cheapcomplexdevices.com>
	<4678.1133888239@sss.pgh.pa.us>
	<4395F1F3.1000803@cheapcomplexdevices.com>
	<15962.1133901211@sss.pgh.pa.us>
	<4395FF61.6060301@cheapcomplexdevices.com>

Ron Mayer <rm_pg@cheapcomplexdevices.com> writes:
> Tom Lane wrote:
>> In this explanation, the reason for the change in plans over time could
>> be a change in the statistics for the other table.  Is "facets" more
>> dynamic than "point_features"?

> Facets is a big table with rather odd distributions of values.
> Many of the values in the indexed columns show up only
> once, others show up hundreds-of-thousands of times.  Perhaps
> an analyze ran and just randomly sampled differently creating
> different stats on that table?

If you have background tasks doing ANALYZEs then this explanation seems
plausible enough.  I'm willing to accept it anyway ...

			regards, tom lane



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