where (A.key1 = 1 and A.key2 = 1 and A.key3 = 1 and A.key4=1 and A.key5=1 and A.key6=1 and A.key7 = 1 or A.key8=1)
and (B.key1 = 1 and B.key2 = 1 and B.key3 = 1 and B.key4=1 and B.key5=1 and B.key6=1 and B.key7 = 1 or B.key8=1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE A index_merge i1,i2,i3,i4,i5,i6,i7?,i8 i2,i3,i4,i5,i6,i7?,i8 X NULL # Using union(intersect(i2,i3,i4,i5,i6,i7?),i8); Using where
1 SIMPLE B index_merge i1,i2,i3,i4,i5,i6,i7?,i8 i2,i3,i4,i5,i6,i7?,i8 X NULL # Using union(intersect(i2,i3,i4,i5,i6,i7?),i8); Using where; Using join buffer