Hi! I have a query that allways creates temporary tables to disk (the ratio created_tmp_disk_tables/created_tmp_tables is close to 0.8, but I think it is 1 for this particular query). This query joins 4 tables, groups by a field a orders by another field (or sometimes an sql variable). When I analyze it, I get "where used, using temporary, using filesort" for the first table of the join (whatever the order of the join), and "where used" for the other ones. I have only 2000 rows scanned forthe first table, and 1 for the 3 other ones. The variables tmp_table_size and max_heap_table_size are both set very high (~512M).
I would like to get rid of those disk tables, to improve the performance of my query. I understand that using a group by and order by on different fields implies the use of a temporary table. What I don't understand is why this table is created on disk, and not in memory? Is it because of the filesort? If yes, how could I get rid of the filesort? If this is not clear enough, I can post a sample query and the result of the explain. Thanks in advance! Arnaud -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
