Re: inheritance: planning time vs children number vs column number - Mailing list pgsql-performance

From Tom Lane
Subject Re: inheritance: planning time vs children number vs column number
Date
Msg-id 17604.1298993631@sss.pgh.pa.us
Whole thread Raw
In response to Re: inheritance: planning time vs children number vs column number  (Marc Cousin <cousinmarc@gmail.com>)
Responses Re: inheritance: planning time vs children number vs column number
Re: inheritance: planning time vs children number vs column number
List pgsql-performance
Marc Cousin <cousinmarc@gmail.com> writes:
> Le mardi 01 mars 2011 07:20:19, Tom Lane a écrit :
>> It's worth pointing out that the only reason this effect is dominating
>> the runtime is that you don't have any statistics for these toy test
>> tables.  If you did, the cycles spent using those entries would dwarf
>> the lookup costs, I think.  So it's hard to get excited about doing
>> anything based on this test case --- it's likely the bottleneck would be
>> somewhere else entirely if you'd bothered to load up some data.

> Yes, for the same test case, with a bit of data in every partition and
> statistics up to date, planning time goes from 20 seconds to 125ms for the 600
> children/1000 columns case. Which is of course more than acceptable.

[ scratches head ... ]  Actually, I was expecting the runtime to go up
not down.  Maybe there's something else strange going on here.

            regards, tom lane

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