Consider a table with 3
varchar columns and a composite index in all of them in the order of
(to B C):
CREATE TABLE `test` ( `a` VARCHAR (255) NOT NULL, `b` VARCHAR (255) NOT NULL, `c` VARCHAR (255) NOT NULL, INDEX (`a`,` b`, `c`) ) MOTOR = InnoDB DEFAULT CHARSET = & # 39; utf8 & # 39 ;;
Will the composite index be used in case of
WHERE a = const and c = const condition? Here it is indicated that it can not be used, however, if we launch
EXPLAIN for such a table / query in a Fiddle DB we see
keysIt seems that it will be used at least for the first part of the condition.