From: Johan De Meersman Date: September 26 2011 12:01pm Subject: Re: Slower performance with LOCK TABLES List-Archive: http://lists.mysql.com/mysql/225829 Message-Id: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit ----- Original Message ----- > From: "Hank" > > Just an update. Using the "load index into cache" statement for the > 200 million row indexed "source" table, my correlated update > statement ran in 1 hour, 45 minutes to update 144 million rows. A 50% > increase in performance! Good to hear :-) Ignore leaves might be a nice trick in this situation, actually. I never thought of it, but the leaves contain the record pointers, which you don't need because you have a covering index. Nice thinking :-) -- Bier met grenadyn Is als mosterd by den wyn Sy die't drinkt, is eene kwezel Hy die't drinkt, is ras een ezel