Re: Bug 4906 -- Left join of subselect incorrect - Mailing list pgsql-bugs

Mathieu Fenniak <mathieu@fenniak.net> writes:
> After running the attached setup.sql.gz SQL script on a PostgreSQL
> 8.4.0 database, the following two queries which should be logically
> identical return different results.  As far as I can tell from the
> query analysis, the LEFT JOIN on query A is happening after
> "ee.projectid = pc.projectid" is filtered; therefore the rows where
> projectid is NULL are not visible in query A.

Yeah, it seems to be confused about whether it can interchange the
order of the semijoin and left join.  I'll take a look.

            regards, tom lane