revision-id: 34a3874b53324234e8e6bf70ea104de85ba6cf05 (mariadb-10.1.41-63-g34a3874b533) parent(s): a41d429765c7ddb528b9b438c68b25ff55d3bd55 author: Varun Gupta committer: Varun Gupta timestamp: 2019-10-27 02:25:07 +0530 message: MDEV-20424: New default value for optimizer_use_condition-selectivity leads to bad plan In the function prev_record_reads where one finds the different row combinations for a subset of partial join, it did not take into account the selectivity of tables involved in the subset of partial join. --- mysql-test/r/selectivity.result | 57 +++++++++++++++++++++++++++++++++++++++++ mysql-test/t/selectivity.test | 29 +++++++++++++++++++++ sql/sql_select.cc | 3 +++ 3 files changed, 89 insertions(+) diff --git a/mysql-test/r/selectivity.result b/mysql-test/r/selectivity.result index d0bbb46cb0a..5fe6986e9ff 100644 --- a/mysql-test/r/selectivity.result +++ b/mysql-test/r/selectivity.result @@ -1753,4 +1753,61 @@ a 1991 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity; DROP TABLE t1; +# +# MDEV-20424: New default value for optimizer_use_condition-selectivity +# leads to bad plan +# +create table t1(a int, b int, c int, d int, key(a,b)); +insert into t1 select 50,seq-1,seq-1,seq from seq_1_to_10; +insert into t1 select seq-1,seq-1,seq-1,seq from seq_1_to_100 limit 90; +create table t2(a int, b int, c int, primary key(a)); +insert into t2 select seq-1,seq-1,seq-1 from seq_1_to_100; +create table t3(a int, b int, c int, primary key(a)); +insert into t3 select seq-1,seq-1,seq-1 from seq_1_to_100 limit 30; +set optimizer_use_condition_selectivity=1; +explain extended select t1.b,t2.a,t3.a,t3.b from t1,t2,t3 +where t1.c = t2.a AND t1.d = t3.a and t1.a = 50 and t1.b <= 100; +id select_type table type possible_keys key key_len ref rows filtered Extra +1 SIMPLE t1 range a a 10 NULL 9 100.00 Using index condition; Using where +1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.d 1 100.00 +1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.c 1 100.00 Using index +Warnings: +Note 1003 select `test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` join `test`.`t2` join `test`.`t3` where ((`test`.`t2`.`a` = `test`.`t1`.`c`) and (`test`.`t3`.`a` = `test`.`t1`.`d`) and (`test`.`t1`.`a` = 50) and (`test`.`t1`.`b` <= 100)) +select t1.b,t2.a,t3.a,t3.b from t1,t2,t3 +where t1.c = t2.a AND t1.d = t3.a and t1.a = 50 and t1.b <= 100; +b a a b +0 0 1 1 +1 1 2 2 +2 2 3 3 +3 3 4 4 +4 4 5 5 +5 5 6 6 +6 6 7 7 +7 7 8 8 +8 8 9 9 +9 9 10 10 +set optimizer_use_condition_selectivity=2; +explain extended select t1.b,t2.a,t3.a,t3.b from t1,t2,t3 +where t1.c = t2.a AND t1.d = t3.a and t1.a = 50 and t1.b <= 100; +id select_type table type possible_keys key key_len ref rows filtered Extra +1 SIMPLE t1 range a a 10 NULL 9 9.00 Using index condition; Using where +1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.d 1 100.00 +1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.c 1 100.00 Using index +Warnings: +Note 1003 select `test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` join `test`.`t2` join `test`.`t3` where ((`test`.`t2`.`a` = `test`.`t1`.`c`) and (`test`.`t3`.`a` = `test`.`t1`.`d`) and (`test`.`t1`.`a` = 50) and (`test`.`t1`.`b` <= 100)) +select t1.b,t2.a,t3.a,t3.b from t1,t2,t3 +where t1.c = t2.a AND t1.d = t3.a and t1.a = 50 and t1.b <= 100; +b a a b +0 0 1 1 +1 1 2 2 +2 2 3 3 +3 3 4 4 +4 4 5 5 +5 5 6 6 +6 6 7 7 +7 7 8 8 +8 8 9 9 +9 9 10 10 +set optimizer_use_condition_selectivity= @@optimizer_use_condition_selectivity; +drop table t1,t2,t3; # End of 10.1 tests diff --git a/mysql-test/t/selectivity.test b/mysql-test/t/selectivity.test index 0deacc390db..a93ad5efb07 100644 --- a/mysql-test/t/selectivity.test +++ b/mysql-test/t/selectivity.test @@ -1205,5 +1205,34 @@ set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivit DROP TABLE t1; +--echo # +--echo # MDEV-20424: New default value for optimizer_use_condition-selectivity +--echo # leads to bad plan +--echo # + +create table t1(a int, b int, c int, d int, key(a,b)); +insert into t1 select 50,seq-1,seq-1,seq from seq_1_to_10; +insert into t1 select seq-1,seq-1,seq-1,seq from seq_1_to_100 limit 90; + +create table t2(a int, b int, c int, primary key(a)); +insert into t2 select seq-1,seq-1,seq-1 from seq_1_to_100; + +create table t3(a int, b int, c int, primary key(a)); +insert into t3 select seq-1,seq-1,seq-1 from seq_1_to_100 limit 30; + +let $query= select t1.b,t2.a,t3.a,t3.b from t1,t2,t3 +where t1.c = t2.a AND t1.d = t3.a and t1.a = 50 and t1.b <= 100; + +set optimizer_use_condition_selectivity=1; +eval explain extended $query; +eval $query; + +set optimizer_use_condition_selectivity=2; +eval explain extended $query; +eval $query; +set optimizer_use_condition_selectivity= @@optimizer_use_condition_selectivity; + +drop table t1,t2,t3; + --echo # End of 10.1 tests diff --git a/sql/sql_select.cc b/sql/sql_select.cc index c6e70c2430c..dfc9f729118 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -8470,7 +8470,10 @@ prev_record_reads(POSITION *positions, uint idx, table_map found_ref) #max_nested_outer_joins=64-1) will not make it any more precise. */ if (pos->records_read) + { found= COST_MULT(found, pos->records_read); + found*= pos->cond_selectivity; + } } } return found;