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MDEV-20424: New default value for optimizer_use_condition-selectivity leads to bad plan

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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.
This commit is contained in:
Varun Gupta
2019-10-27 01:48:00 +05:30
parent 6f86150ab3
commit 8afe4bba2e
4 changed files with 146 additions and 0 deletions
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57
mysql-test/r/selectivity.result
View File

@ -1753,4 +1753,61 @@ a
1991 1991
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity; set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
DROP TABLE t1; 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 # End of 10.1 tests

57
mysql-test/r/selectivity_innodb.result
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@ -1763,6 +1763,63 @@ a
1991 1991
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity; set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
DROP TABLE t1; 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 11 100.00 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 11 11.00 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 # End of 10.1 tests
set optimizer_switch=@save_optimizer_switch_for_selectivity_test; set optimizer_switch=@save_optimizer_switch_for_selectivity_test;
set @tmp_ust= @@use_stat_tables; set @tmp_ust= @@use_stat_tables;

29
mysql-test/t/selectivity.test
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@ -1205,5 +1205,34 @@ set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivit
DROP TABLE t1; 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 --echo # End of 10.1 tests

3
sql/sql_select.cc
View File

@ -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. #max_nested_outer_joins=64-1) will not make it any more precise.
*/ */
if (pos->records_read) if (pos->records_read)
{
found= COST_MULT(found, pos->records_read); found= COST_MULT(found, pos->records_read);
found*= pos->cond_selectivity;
}
} }
} }
return found; return found;