Re: comma vs cross join question - Mailing list pgsql-general

From Tom Lane
Subject Re: comma vs cross join question
Date
Msg-id 15744.1302287050@sss.pgh.pa.us
Whole thread Raw
In response to comma vs cross join question  (Jason Long <mailing.lists@octgsoftware.com>)
List pgsql-general
Jason Long <mailing.lists@octgsoftware.com> writes:
> I recently upgraded to JBoss AS 6.0.0.Final which includes a newer
> version of Hibernate.
> Previously the Postgres dialect was using a comma, but now is is using
> cross join.
> With the cross join this query never completes.  With the comma the
> query is identical to what was there before and takes less than 300 ms.

Those should be semantically equivalent AFAICS.  Do you maybe have
join_collapse_limit set to a smaller-than-default value?  If not, are
any of those tables really join views?

Please see
http://wiki.postgresql.org/wiki/SlowQueryQuestions
if you need further help, because there's not enough information here
to do more than guess wildly.

            regards, tom lane

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