Nobody complains where the database is fast. But adding one index speeds things up. But the second index makes things worse? There is a lot of mythology about indexes in the MySQL area and this talk will show that getting performance out of an index is simple engineering and not magic. You will walk out of this session knowing how indexes are built, how to use them to provide better information to the query optimizer, and how to make sure that what you are doing is a positive change and not hurting your instance performance.