Maybe I'm wrong :)
On Tuesday, July 21, 2009, John Daisley <john.dais...@mypostoffice.co.uk> wrote: > > > On Tue, 2009-07-21 at 19:42 +0200, Morten Primdahl wrote: > >> On Jul 21, 2009, at 3:27 PM, Johnny Withers wrote: >> >> > MySQL is unable to use your index when you use IN and/or OR on yoru >> > column. >> >> Is this really true? > > > No its not true! Try running OPTIMIZE TABLE on the affected table, then > run the query again and see if the other index is used! > > > > >> >> I'm reading "High Performance MySQL 2nd ed." these days and >> specifically got the impression that using IN will allow usage of the >> index. The below quote is from the book, and the "multiple equality >> condition" refers to an IN (...) expression. >> >> "... we draw a distinction between ranges of values and multiple >> equality conditions.The second query is a multiple equality condition, >> in our terminology. We’re not just being picky: these two kinds of >> index accesses perform differently. The range condition makes MySQL >> ignore any further columns in the index, but the multiple equality >> condition doesn’t have that limitation." >> >> >> >> >> > > John Daisley > Email: john.dais...@butterflysystems.co.uk > Mobile: +44 (0)7812 451238 > > MySQL Certified Database Administrator (CMDBA) > MySQL Certified Developer (CMDEV) > MySQL Certified Associate (CMA) > Comptia A+ Certified Professional IT Technician > > ------- > > Life's journey is not to arrive at the grave safely in a well preserved > body, but rather to slide in sideways, thoroughly used up, totally worn > out and screaming "Wow! what a ride!" > -- ----------------------------- Johnny Withers 601.209.4985 joh...@pixelated.net -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
