# # Bug #725050: print keyuse info when hash join is used # create table t1 (a int, b int); insert into t1 values (2,2), (1,1); create table t2 (a int); insert into t2 values (2), (3); set session join_cache_level=3; set @@debug_dbug= 'd,opt'; explain select t1.b from t1,t2 where t1.b=t2.a; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 Using where 1 SIMPLE t2 hash_ALL NULL #hash#$hj 5 test.t1.b 2 Using where; Using join buffer (flat, BNLH join) select t1.b from t1,t2 where t1.b=t2.a; b 2 set session join_cache_level=default; drop table t1,t2;