From: Cabbar Duzayak Date: July 8 2012 1:29pm Subject: Re: Subquery taking too much time on 5.5.18? List-Archive: http://lists.mysql.com/mysql/227788 Message-Id: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 mysql> SELECT @@optimizer_switch; +------------------------------------------------------------------------------------------------------------------------+ | @@optimizer_switch | +------------------------------------------------------------------------------------------------------------------------+ | index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on | +------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec) On Sat, Jul 7, 2012 at 8:01 PM, Peter Brawley wrote: > On 2012-07-07 9:52 AM, Cabbar Duzayak wrote: >> >> Hmm, >> >> Looking at the link http://www.artfulsoftware.com/infotree/queries.php >> and explanations here, EXISTS() should have performed better, but does >> not seem to??? I stopped it after about 5 minutes. >> >> I tried both: >> >> SELECT * FROM A WHERE EXISTS (SELECT * FROM B WHERE A.id=B.A_ID and >> B.name like 'X%'); >> >> and >> >> SELECT * FROM A WHERE EXISTS (SELECT B.A_ID FROM B WHERE A.id=B.A_ID >> and B.name like 'X%'); >> >> Both are slow... > > > What's the optimizer_switch setting? > > PB > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/mysql >