Unused indexes by single query
用INFORMATION_SCHEMA中的statistics找出沒用到的index。
SELECT DISTINCT s.TABLE_SCHEMA, s.TABLE_NAME, s.INDEX_NAME
FROM information_schema.statistics sLEFT JOIN information_schema.index_statistics `is`ON(s.TABLE_SCHEMA=is.TABLE_SCHEMA AND
s.TABLE_NAME=is.TABLE_NAME AND s.INDEX_NAME=is.INDEX_NAME)

