Re: 7.4 - FK constraint performance - Mailing list pgsql-sql

From Tom Lane
Subject Re: 7.4 - FK constraint performance
Date
Msg-id 27696.1076647796@sss.pgh.pa.us
Whole thread Raw
In response to Re: 7.4 - FK constraint performance  (ow <oneway_111@yahoo.com>)
List pgsql-sql
ow <oneway_111@yahoo.com> writes:
> --- Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Can't see how we optimize your case without pessimizing more-common cases.

> I think other RDBMSs simply use preset value instead of partial table
> scan when there's not enough stat info. Might be a better way.

The problem here cannot be described as "not enough stat info".  The
available stats are complete and they point very strongly to the
conclusion that searches in the large table should be seqscans.
To do otherwise would be folly in general, even if it happens to
be the correct thing in this particular example.
        regards, tom lane


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