Fortunately there are big improvements coming to the specific case of subqueries in MySQL 5.6.3 [1]. MariaDB (a MySQL fork) also has several further optimizatio

Fortunately there are big improvements coming to the specific case of subqueries in MySQL 5.6.3 [1]. MariaDB (a MySQL fork) also has several further optimizations [2]. [1] http://dev.mysql.com/doc/refman/5.6/en/from-clause-subquery-optimization.html http://dev.mysql.com/doc/refman/5.6/en/from-clause-subquery-... [2] https://kb.askmonty.org/en/subquery-optimizations-map/ https://kb.askmonty.org/en/subquery-optimizations-map/