Re: Missed index opportunity for outer join? - Mailing list pgsql-performance

From Tom Lane
Subject Re: Missed index opportunity for outer join?
Date
Msg-id 16502.1133904299@sss.pgh.pa.us
Whole thread Raw
In response to Re: Missed index opportunity for outer join?  (Ron Mayer <rm_pg@cheapcomplexdevices.com>)
Responses Re: Missed index opportunity for outer join?
List pgsql-performance
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

pgsql-performance by date:

Previous
From: "Brandon Metcalf"
Date:
Subject: Context switching and Xeon processors
Next
From: Tom Lane
Date:
Subject: Re: Context switching and Xeon processors