…to BKA algorithm of MySQL 5.6. Test Case C – Join a small table with a large table with a WHERE clause on a non-indexed column The SQL used…the best one. So we can force the join algorithm used by setting appropriate values of “join_cache_level”. For example in my test I forced the optimizer to use…
Post: Multiple column index vs multiple indexes
August 22, 2008 By 13 Comments
…The table contained about 18M rows though was small enough to fit in the systems memory. I’ve benchmarked simple queries using where clause which covers multiple…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 100 Comments
…to be adjusted in the future. The main thing to watch for, if you do not have full where clause…to use in ORDER BY in other table. Here is example when ORDER BY is done by second table which requires filesort: mysql…
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 31 Comments
…where clause from first column selects 5% of the rows and applying where clause on second column brings it down to 1% using intersection makes sense. If second where clause…
