Re: anti-join chosen even when slower than old plan - Mailing list pgsql-performance

From Tom Lane
Subject Re: anti-join chosen even when slower than old plan
Date
Msg-id 19475.1289503020@sss.pgh.pa.us
Whole thread Raw
In response to Re: anti-join chosen even when slower than old plan  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-performance
Robert Haas <robertmhaas@gmail.com> writes:
> On Thu, Nov 11, 2010 at 1:23 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I do think that something based around a settable-per-table caching
>> percentage might be a reasonable way to proceed. �But the devil is in
>> the details, and we don't have those yet.

> I think one of the larger devils in the details is deciding how to
> estimate the assumed caching percentage when the user hasn't specified
> one.

I was imagining something very similar to the handling of seq_page_cost,
ie, there's a GUC controlling the system-wide default and then you can
override that per-table.  But the real question is whether per-table
is a useful granularity to control it at.  See my later message.

            regards, tom lane

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