Yang Zhang <yanghatespam@xxxxxxxxx> writes: > On Thu, Sep 15, 2011 at 1:22 AM, Tomas Vondra <tv@xxxxxxxx> wrote: >> [ use a left join instead of NOT IN ] > This worked great, thank you. Too bad the planner isn't smart enough > to do this yet! It never will be, because they're not equivalent queries. NOT IN has different (and very hard-to-optimize) behavior in the face of NULLs in the right-hand table. The moral of the story is avoid NOT IN. You could use NOT EXISTS, which is less of a notational change than recasting as a left join. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
