diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result index e2ed43158f1..1c75aa66287 100644 --- a/mysql-test/r/subselect.result +++ b/mysql-test/r/subselect.result @@ -7240,6 +7240,22 @@ a 5 SET @@optimizer_switch= @optimiser_switch_save; DROP TABLE t1, t2, t3; +# +# MDEV-16820: impossible where with inexpensive subquery +# +create table t1 (a int) engine=myisam; +insert into t1 values (3), (1), (7); +create table t2 (b int, index idx(b)); +insert into t2 values (2), (5), (3), (2); +explain select * from t1 where (select max(b) from t2) = 10; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select * from t1 where (select max(b) from t2) = 10 and t1.a > 3; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +drop table t1,t2; End of 5.5 tests # End of 10.0 tests # diff --git a/mysql-test/r/subselect_no_exists_to_in.result b/mysql-test/r/subselect_no_exists_to_in.result index 6306cfff89d..0bd14a535e0 100644 --- a/mysql-test/r/subselect_no_exists_to_in.result +++ b/mysql-test/r/subselect_no_exists_to_in.result @@ -7240,6 +7240,22 @@ a 5 SET @@optimizer_switch= @optimiser_switch_save; DROP TABLE t1, t2, t3; +# +# MDEV-16820: impossible where with inexpensive subquery +# +create table t1 (a int) engine=myisam; +insert into t1 values (3), (1), (7); +create table t2 (b int, index idx(b)); +insert into t2 values (2), (5), (3), (2); +explain select * from t1 where (select max(b) from t2) = 10; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select * from t1 where (select max(b) from t2) = 10 and t1.a > 3; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +drop table t1,t2; End of 5.5 tests # End of 10.0 tests # diff --git a/mysql-test/r/subselect_no_mat.result b/mysql-test/r/subselect_no_mat.result index 0db1b031133..a3b7871bb7e 100644 --- a/mysql-test/r/subselect_no_mat.result +++ b/mysql-test/r/subselect_no_mat.result @@ -7233,6 +7233,22 @@ a 5 SET @@optimizer_switch= @optimiser_switch_save; DROP TABLE t1, t2, t3; +# +# MDEV-16820: impossible where with inexpensive subquery +# +create table t1 (a int) engine=myisam; +insert into t1 values (3), (1), (7); +create table t2 (b int, index idx(b)); +insert into t2 values (2), (5), (3), (2); +explain select * from t1 where (select max(b) from t2) = 10; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select * from t1 where (select max(b) from t2) = 10 and t1.a > 3; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +drop table t1,t2; End of 5.5 tests # End of 10.0 tests # diff --git a/mysql-test/r/subselect_no_opts.result b/mysql-test/r/subselect_no_opts.result index 1fa6f385b2b..9dcc690448f 100644 --- a/mysql-test/r/subselect_no_opts.result +++ b/mysql-test/r/subselect_no_opts.result @@ -7231,6 +7231,22 @@ a 5 SET @@optimizer_switch= @optimiser_switch_save; DROP TABLE t1, t2, t3; +# +# MDEV-16820: impossible where with inexpensive subquery +# +create table t1 (a int) engine=myisam; +insert into t1 values (3), (1), (7); +create table t2 (b int, index idx(b)); +insert into t2 values (2), (5), (3), (2); +explain select * from t1 where (select max(b) from t2) = 10; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select * from t1 where (select max(b) from t2) = 10 and t1.a > 3; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +drop table t1,t2; End of 5.5 tests # End of 10.0 tests # diff --git a/mysql-test/r/subselect_no_scache.result b/mysql-test/r/subselect_no_scache.result index 986542bd0bf..7b3c001f6b3 100644 --- a/mysql-test/r/subselect_no_scache.result +++ b/mysql-test/r/subselect_no_scache.result @@ -7246,6 +7246,22 @@ a 5 SET @@optimizer_switch= @optimiser_switch_save; DROP TABLE t1, t2, t3; +# +# MDEV-16820: impossible where with inexpensive subquery +# +create table t1 (a int) engine=myisam; +insert into t1 values (3), (1), (7); +create table t2 (b int, index idx(b)); +insert into t2 values (2), (5), (3), (2); +explain select * from t1 where (select max(b) from t2) = 10; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select * from t1 where (select max(b) from t2) = 10 and t1.a > 3; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +drop table t1,t2; End of 5.5 tests # End of 10.0 tests # diff --git a/mysql-test/r/subselect_no_semijoin.result b/mysql-test/r/subselect_no_semijoin.result index d5fcc17f08c..a0625246e2b 100644 --- a/mysql-test/r/subselect_no_semijoin.result +++ b/mysql-test/r/subselect_no_semijoin.result @@ -7231,6 +7231,22 @@ a 5 SET @@optimizer_switch= @optimiser_switch_save; DROP TABLE t1, t2, t3; +# +# MDEV-16820: impossible where with inexpensive subquery +# +create table t1 (a int) engine=myisam; +insert into t1 values (3), (1), (7); +create table t2 (b int, index idx(b)); +insert into t2 values (2), (5), (3), (2); +explain select * from t1 where (select max(b) from t2) = 10; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select * from t1 where (select max(b) from t2) = 10 and t1.a > 3; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +drop table t1,t2; End of 5.5 tests # End of 10.0 tests # diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test index 7e9e5a731bc..1048e5a5a27 100644 --- a/mysql-test/t/subselect.test +++ b/mysql-test/t/subselect.test @@ -6102,6 +6102,21 @@ and t1.a in (select `test`.`t3`.`c` from `test`.`t3`); SET @@optimizer_switch= @optimiser_switch_save; DROP TABLE t1, t2, t3; +--echo # +--echo # MDEV-16820: impossible where with inexpensive subquery +--echo # + +create table t1 (a int) engine=myisam; +insert into t1 values (3), (1), (7); + +create table t2 (b int, index idx(b)); +insert into t2 values (2), (5), (3), (2); + +explain select * from t1 where (select max(b) from t2) = 10; +explain select * from t1 where (select max(b) from t2) = 10 and t1.a > 3; + +drop table t1,t2; + --echo End of 5.5 tests --echo # End of 10.0 tests diff --git a/sql/item.h b/sql/item.h index ce07f993dc4..8fad8dadf22 100644 --- a/sql/item.h +++ b/sql/item.h @@ -1614,6 +1614,11 @@ public: virtual bool limit_index_condition_pushdown_processor(void *arg) { return 0; } virtual bool exists2in_processor(void *arg) { return 0; } virtual bool find_selective_predicates_list_processor(void *arg) { return 0; } + bool cleanup_is_expensive_cache_processor(void *arg) + { + is_expensive_cache= (int8)(-1); + return 0; + } /* TRUE if the expression depends only on the table indicated by tab_map diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 1fa21437266..4cabf5c1b40 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -1335,6 +1335,13 @@ JOIN::optimize_inner() if (optimize_constant_subqueries()) DBUG_RETURN(1); + if (conds && conds->has_subquery()) + (void) conds->walk(&Item::cleanup_is_expensive_cache_processor, + 0, (void *) 0); + if (having && having->has_subquery()) + (void) having->walk(&Item::cleanup_is_expensive_cache_processor, + 0, (void *) 0); + if (setup_jtbm_semi_joins(this, join_list, &conds)) DBUG_RETURN(1);