https://mariadb.com/kb/en/mariadb/semi-join-subquery-optimizations/
http://dev.mysql.com/doc/refman/5.7/en/subquery-optimization.html
https://mariadb.com/kb/en/mariadb/loosescan-strategy/
https://mariadb.com/kb/en/mariadb/semi-join-materialization-strategy/
https://www.quora.com/SQL-What-is-the-difference-between-a-correlated-and-an-uncorrelated-subquery
https://mariadb.com/kb/en/mariadb/optimization-strategies/
https://mariadb.com/kb/en/mariadb/optimization-and-tuning/
MYSQL 优化
标签：blank ons strategy diff sql 优化 ora tween tuning join