Re: Left Join Performance vs Inner Join Performance

От: Tom Lane
Тема: Re: Left Join Performance vs Inner Join Performance
Дата: ,
Msg-id: 8321.1136954300@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Left Join Performance vs Inner Join Performance  ("Dave Dutcher")
Список: pgsql-performance

"Dave Dutcher" <> writes:
> I have an inner join query that runs fast, but I when I change to a left
> join the query runs 96 times slower.

This looks like an issue that is fixed in the latest set of releases,
namely that OUTER JOIN ON conditions that reference only the inner
side of the join weren't getting pushed down into indexquals.  See
thread here:
http://archives.postgresql.org/pgsql-performance/2005-12/msg00134.php
and patches in this and the following messages:
http://archives.postgresql.org/pgsql-committers/2005-12/msg00105.php

            regards, tom lane


В списке pgsql-performance по дате сообщения:

От: Alessandro Baretta
Дата:
Сообщение: Re: 500x speed-down: Wrong statistics!
От: Bendik Rognlien Johansen
Дата:
Сообщение: Slow query with joins