I have run EXPLAIN and have a question. I have a table with name city and state. I have indexes on city, state and city_state and state_city (just for imformative purposes, would never leave them all). If I run an EXPLAIN select name from t1 where city = 'x' and state = 'y'; EXPLAIN Extra says "Using where"; key says city_st; possible_keys says state, city, city_st, st_city; ref says "const, const"; select_type says SIMPLE; type = "ref".
My question is why wouldn't it be an "index" type and why wouldn't it say "Using index" in the Extra column?