On Mon, Jun 11, 2007 at 03:01:08PM +0300, Andrus wrote: > > delete from firma1.rid where dokumnr not in (select dokumnr from > >firma1.dok) > > Yes, it is nonsensial. However, this command should run fast even if it is > nonsensial. For future reference, I beleive the problem is the NOT IN. It has this "feature" where if any of the rows it searches has a NULL, it will return FALSE for *all* rows. So the whole table has to be scanned to check that there arn't any NULLs, before a single row can be returned. This is why it can't be converted to a join. Now, you may argue that in your case this doesn't apply, which may be true, but it's always been a difficult construct to optimise... (and somewhat surprising for people with they didn't realise the null-effect). The most efficient way you write this is with an OUTER JOIN. Have a nice day, -- Martijn van Oosterhout <kleptog@xxxxxxxxx> http://svana.org/kleptog/ > From each according to his ability. To each according to his ability to litigate.
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