Hi, I'm not saying I fully understand the MySQL optimizer, as I never had to deal with it before... but:
Why should it use an index if the statement is returning ALL rows? It might be faster to read them into memory ( 75853 isn't really much ) and sort them there instead of moving the diskhead back and forth between the index and the data. > i'm having a problem with mysql. when i put an index on a > datetime column, it's never used. > > for example the > sql: 'EXPLAIN SELECT * FROM actions ORDER BY datum' > > shows: > table type possible_keys key key_len ref rows Extra > actions ALL NULL NULL NULL NULL 75853 Using filesort > > even if i use the > sql: 'EXPLAIN SELECT * FROM actions USE INDEX (datum) ORDER BY datum' > > mysql doesn' use the index :-(( With regards, Martijn Tonies Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL Server. Upscene Productions http://www.upscene.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
