drop table if exists t0,t1,t2,t3; # # MDEV-7885: EXPLAIN shows wrong info for ORDER BY query # create table t0(a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1(a int); insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C; create table t2 (key1 int, col1 int, key(key1)); insert into t2 select a,a from t0; insert into t2 select 15,15 from t1; alter table t2 add key2 int, add key(key2); # This must show "Using filesort": explain select * from t2 ignore index for order by (key1) where col1<0 order by key1 limit 10; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 1010 Using where; Using filesort drop table t0, t1, t2; # # MDEV-8857: [Upstream too] EXPLAIN incorrectly shows Distinct for tables using join buffer # create table t0(a int); insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 (a int, filler char(200), key(a)); insert into t1 select A.a + B.a* 10, 'AAAAAAAAAAAAAAAAAAAA' from t0 A, t0 B where B.a in (0,1); explain select distinct A.a from t0 A, t1 B where A.a+B.a> 0; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE A ALL NULL NULL NULL NULL 10 Using temporary 1 SIMPLE B index NULL a 5 NULL 20 Using where; Using index; Using join buffer (flat, BNL join) drop table t0, t1;