Hi, I'm still stuck with my SQL query that is slow but really shouldn't be.
The problem is that I cannot create a simple test case. I could only provide you a whole lot of pages of PHP code and SQL queries to explain the problem. I have now three versions of my query. One with a sub select, which takes 40 ms and works. One with a left join instead, which takes 40 ms and works. And one with an inner join instead, which takes 3 ms and doesn't work. The number of left-joined rows should be around 5, so what can make it take 35 ms to join those handful of rows? MySQL server version is 5.0.67 and 5.1.41 (just updated). Here's a small impression of my query: SELECT t.TagId, t.TagName, tk.UserId FROM message_revision_tag mrt JOIN tag t USING (TagId) LEFT JOIN keylist tk ON -- Here's the left join (tk.KeylistId = t.ReadAccessKeylistId AND tk.UserId IN (22943, 10899)) WHERE mrt.MessageId = 72 AND mrt.RevisionNumber = 1 AND t.ReadAccessKeylistId IS NOT NULL; This is only a sub-query of a larger search query in my PHP application. MySQL workbench can't show query timings so I can'T say how long this part of the query takes. It's probably fast, but it is applied to ~600 other rows to determine whether they should be included in the results or not. -- Yves Goergen "LonelyPixel" <nospam.l...@unclassified.de> Visit my web laboratory at http://beta.unclassified.de -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org