Simon, On Wed, May 27, 2009 at 11:23 AM, Simon J Mudd <sjm...@pobox.com> wrote: > per...@elem.com (Perrin Harkins) writes: > >> On Wed, May 27, 2009 at 6:43 AM, Simon J Mudd <sjm...@pobox.com> wrote: >> > So is the format of the DELETE FROM .. WHERE ... IN ( ... ) clause I >> > propose valid and SHOULD the optimiser recognise this and be expected >> > to just find the 2 rows by searching on the primary key? >> >> Not according to the docs: >> http://dev.mysql.com/doc/refman/5.1/en/comparison-operators.html#function_in > > I'm not sure that the reference makes anything clear. The statements > are wrote ARE valid SQL and even though containing mulitiple column > values ARE "constants". > > Problem is I'm finding it hard to find a definitive reference to something > like this. I'll have to check my Joe Celko books to see if he mentions ths.
Nothing's wrong with the SQL -- it's just that MySQL doesn't optimize this type of query well. See http://code.openark.org/blog/mysql/mysql-not-being-able-to-utilize-a-compound-index Regards Baron -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
