On Wed, Jul 1, 2009 at 11:52 AM, Tom Lane<t...@sss.pgh.pa.us> wrote: > Scott Marlowe <scott.marl...@gmail.com> writes: >> Sometimes putting a where clause portion into the on clause helps. >> like: >> select * from a left join b on (a.id=b.id) where a.somefield=2 >> might run faster with >> select * from a left join b on (a.id=bid. and a.somefield=2); >> but it's hard to say. > > Uh, those are not the same query ... they will give different results > for rows with a.somefield different from 2.
How so? Neither should return any rows with a.somefield <> 2. Or are you talking where a.somefield is null? -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
