revision-id: 62d269ea914de5b9225e0584cca52444e09c1c56 (mariadb-10.2.31-986-g62d269e) parent(s): d06205ba3713da6c5875f124d5e431d3704aad1d author: Igor Babaev committer: Igor Babaev timestamp: 2021-05-31 22:37:15 -0700 message: MDEV-25635 Assertion failure when pushing from HAVING into WHERE of view This bug could manifest itself after pushing a where condition over a mergeable derived table / view / CTE DT into a grouping view / derived table / CTE V whose item list contained set functions with constant arguments such as MIN(2), SUM(1) etc. In such cases the field references used in the condition pushed into the view V that correspond set functions are wrapped into Item_direct_view_ref wrappers. Due to a wrong implementation of the virtual method const_item() for the class Item_direct_view_ref the wrapped set functions with constant arguments could be erroneously taken for constant items. This could lead to a wrong result set returned by the main select query in 10.2. In 10.4 where a possibility of pushing condition from HAVING into WHERE had been added this could cause a crash. --- mysql-test/r/derived_cond_pushdown.result | 39 +++++++++++++++++++++++++++++++ mysql-test/t/derived_cond_pushdown.test | 25 ++++++++++++++++++++ sql/item.h | 5 +++- 3 files changed, 68 insertions(+), 1 deletion(-) diff --git a/mysql-test/r/derived_cond_pushdown.result b/mysql-test/r/derived_cond_pushdown.result index 25237aa..28532ae 100644 --- a/mysql-test/r/derived_cond_pushdown.result +++ b/mysql-test/r/derived_cond_pushdown.result @@ -10634,4 +10634,43 @@ m 7 drop view v1; drop table t1; +# +# MDEV-25635: pushdown into grouping view using aggregate functions +# with constant arguments via a mergeable derived table +# +create table t1 (a int); +insert into t1 values (3), (7), (1), (3), (7), (7), (3); +create view v1 as select a, sum(1) as f, sum(1) as g from t1 group by a; +select * from v1; +a f g +1 1 1 +3 3 3 +7 3 3 +select * from (select * from v1) as dt where a=f and a=g; +a f g +1 1 1 +3 3 3 +explain extended select * from (select * from v1) as dt where a=f and a=g; +id select_type table type possible_keys key key_len ref rows filtered Extra +1 PRIMARY <derived3> ALL NULL NULL NULL NULL 7 100.00 Using where +3 DERIVED t1 ALL NULL NULL NULL NULL 7 100.00 Using temporary; Using filesort +Warnings: +Note 1003 select `v1`.`a` AS `a`,`v1`.`f` AS `f`,`v1`.`g` AS `g` from `test`.`v1` where `v1`.`a` = `v1`.`f` and `v1`.`a` = `v1`.`g` +create view v2 as select a, min(1) as f, min(1) as g from t1 group by a; +select * from v2; +a f g +1 1 1 +3 1 1 +7 1 1 +select * from (select * from v2) as dt where a=f and a=g; +a f g +1 1 1 +explain extended select * from (select * from v2) as dt where a=f and a=g; +id select_type table type possible_keys key key_len ref rows filtered Extra +1 PRIMARY <derived3> ALL NULL NULL NULL NULL 7 100.00 Using where +3 DERIVED t1 ALL NULL NULL NULL NULL 7 100.00 Using temporary; Using filesort +Warnings: +Note 1003 select `v2`.`a` AS `a`,`v2`.`f` AS `f`,`v2`.`g` AS `g` from `test`.`v2` where `v2`.`f` = `v2`.`a` and `v2`.`g` = `v2`.`a` +drop view v1,v2; +drop table t1; # End of 10.2 tests diff --git a/mysql-test/t/derived_cond_pushdown.test b/mysql-test/t/derived_cond_pushdown.test index 31b4904..58f38ac 100644 --- a/mysql-test/t/derived_cond_pushdown.test +++ b/mysql-test/t/derived_cond_pushdown.test @@ -2212,4 +2212,29 @@ select * from v1 where m > 0; drop view v1; drop table t1; +--echo # +--echo # MDEV-25635: pushdown into grouping view using aggregate functions +--echo # with constant arguments via a mergeable derived table +--echo # + +create table t1 (a int); +insert into t1 values (3), (7), (1), (3), (7), (7), (3); + +create view v1 as select a, sum(1) as f, sum(1) as g from t1 group by a; +select * from v1; +let $q1= +select * from (select * from v1) as dt where a=f and a=g; +eval $q1; +eval explain extended $q1; + +create view v2 as select a, min(1) as f, min(1) as g from t1 group by a; +select * from v2; +let $q2= +select * from (select * from v2) as dt where a=f and a=g; +eval $q2; +eval explain extended $q2; + +drop view v1,v2; +drop table t1; + --echo # End of 10.2 tests diff --git a/sql/item.h b/sql/item.h index c94709c..76be66d 100644 --- a/sql/item.h +++ b/sql/item.h @@ -4952,7 +4952,10 @@ class Item_direct_view_ref :public Item_direct_ref table_map used_tables() const; void update_used_tables(); table_map not_null_tables() const; - bool const_item() const { return used_tables() == 0; } + bool const_item() const + { + return (*ref)->const_item() && (null_ref_table == NO_NULL_TABLE); + } TABLE *get_null_ref_table() const { return null_ref_table; } bool walk(Item_processor processor, bool walk_subquery, void *arg) {