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MDEV-17017 Explain for query using derived table specified with a table

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value constructor shows wrong number of rows

If the specification of a derived table contained a table value constructor
then the optimizer incorrectly estimated the number of rows in the derived
table. This happened because the optimizer did not take into account the
number of rows in the constructor. The wrong estimate could lead to choosing
inefficient execution plans.
This commit is contained in:
Igor Babaev
2018-08-18 22:57:20 -07:00
parent 0dadb96e16
commit a1fd25c22b
9 changed files with 115 additions and 23 deletions
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30
mysql-test/main/opt_tvc.result
View File

@ -486,34 +486,32 @@ a b
deallocate prepare stmt;
# use inside out access from tvc rows
set @@in_predicate_conversion_threshold= default;
select * from t3 where a in (1,4,10);
select * from t3 where a in (1,4);
a b
1 abc
1 todd
1 sm
4 yq
10 abc
explain extended select * from t3 where a in (1,4,10);
explain extended select * from t3 where a in (1,4);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t3 range idx idx 5 NULL 5 100.00 Using index condition
1 SIMPLE t3 range idx idx 5 NULL 4 100.00 Using index condition
Warnings:
Note 1003 select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where `test`.`t3`.`a` in (1,4,10)
Note 1003 select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` where `test`.`t3`.`a` in (1,4)
set @@in_predicate_conversion_threshold= 2;
select * from t3 where a in (1,4,10);
select * from t3 where a in (1,4);
a b
1 abc
1 todd
1 sm
4 yq
10 abc
explain extended select * from t3 where a in (1,4,10);
explain extended select * from t3 where a in (1,4);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <subquery2> ALL distinct_key NULL NULL NULL 2 100.00
1 PRIMARY t3 ref idx idx 5 tvc_0.1 3 100.00
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` semi join ((values (1),(4),(10)) `tvc_0`) where `test`.`t3`.`a` = `tvc_0`.`1`
Note 1003 /* select#1 */ select `test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t3` semi join ((values (1),(4)) `tvc_0`) where `test`.`t3`.`a` = `tvc_0`.`1`
# use vectors in IN predeicate
set @@in_predicate_conversion_threshold= 4;
select * from t1 where (a,b) in ((1,2),(3,4));
@ -540,9 +538,9 @@ explain extended select * from t2
where (a,b) in ((1,2),(8,9)) and
(a,c) in ((1,3),(8,0),(5,1));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY <subquery2> ALL distinct_key NULL NULL NULL 2 100.00
1 PRIMARY <subquery2> ALL distinct_key NULL NULL NULL 3 100.00
1 PRIMARY t2 ALL NULL NULL NULL NULL 6 100.00 Using where; Using join buffer (flat, BNL join)
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 3 100.00
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` semi join ((values (1,3),(8,0),(5,1)) `tvc_0`) where `test`.`t2`.`a` = `tvc_0`.`1` and `test`.`t2`.`c` = `tvc_0`.`3` and (`tvc_0`.`1`,`test`.`t2`.`b`) in (<cache>((1,2)),<cache>((8,9)))
@ -570,7 +568,7 @@ explain extended select * from t1
where (a,b) not in ((1,2),(8,9), (5,1));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 3 100.00
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where !<expr_cache><`test`.`t1`.`a`,`test`.`t1`.`b`>(<in_optimizer>((`test`.`t1`.`a`,`test`.`t1`.`b`),(`test`.`t1`.`a`,`test`.`t1`.`b`) in ( <materialize> (/* select#2 */ select `tvc_0`.`1`,`tvc_0`.`2` from (values (1,2),(8,9),(5,1)) `tvc_0` ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`1` and `test`.`t1`.`b` = `<subquery2>`.`2`))))
@ -578,7 +576,7 @@ explain extended select * from t1
where (a,b) not in (select * from (values (1,2),(8,9), (5,1)) as tvc_0);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 3 100.00
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where !<expr_cache><`test`.`t1`.`a`,`test`.`t1`.`b`>(<in_optimizer>((`test`.`t1`.`a`,`test`.`t1`.`b`),(`test`.`t1`.`a`,`test`.`t1`.`b`) in ( <materialize> (/* select#2 */ select `tvc_0`.`1`,`tvc_0`.`2` from (values (1,2),(8,9),(5,1)) `tvc_0` ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`1` and `test`.`t1`.`b` = `<subquery2>`.`2`))))
@ -592,7 +590,7 @@ explain extended select * from t1
where b < 7 and (a,b) not in ((1,2),(8,9), (5,1));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 6 100.00 Using where
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 3 100.00
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where `test`.`t1`.`b` < 7 and !<expr_cache><`test`.`t1`.`a`,`test`.`t1`.`b`>(<in_optimizer>((`test`.`t1`.`a`,`test`.`t1`.`b`),(`test`.`t1`.`a`,`test`.`t1`.`b`) in ( <materialize> (/* select#2 */ select `tvc_0`.`1`,`tvc_0`.`2` from (values (1,2),(8,9),(5,1)) `tvc_0` ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`1` and `test`.`t1`.`b` = `<subquery2>`.`2`))))
@ -608,7 +606,7 @@ explain extended select * from t2
where (a,c) not in ((1,2),(8,9), (5,1));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 6 100.00 Using where
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2 100.00
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 3 100.00
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Note 1003 /* select#1 */ select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t2` where !<expr_cache><`test`.`t2`.`a`,`test`.`t2`.`c`>(<in_optimizer>((`test`.`t2`.`a`,`test`.`t2`.`c`),(`test`.`t2`.`a`,`test`.`t2`.`c`) in ( <materialize> (/* select#2 */ select `tvc_0`.`1`,`tvc_0`.`2` from (values (1,2),(8,9),(5,1)) `tvc_0` ), <primary_index_lookup>(`test`.`t2`.`a` in <temporary table> on distinct_key where `test`.`t2`.`a` = `<subquery2>`.`1` and `test`.`t2`.`c` = `<subquery2>`.`2`))))
@ -632,7 +630,7 @@ i
EXPLAIN EXTENDED SELECT * FROM t1 WHERE i IN (NULL, NULL, NULL, NULL, NULL);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00
1 PRIMARY <derived3> ALL NULL NULL NULL NULL 2 100.00 Using where; FirstMatch(t1); Using join buffer (flat, BNL join)
1 PRIMARY <derived3> ALL NULL NULL NULL NULL 5 100.00 Using where; FirstMatch(t1); Using join buffer (flat, BNL join)
3 DERIVED NULL NULL NULL NULL NULL NULL NULL NULL No tables used
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`i` AS `i` from `test`.`t1` semi join ((values (NULL),(NULL),(NULL),(NULL),(NULL)) `tvc_0`) where `test`.`t1`.`i` = `tvc_0`.`NULL`

2
mysql-test/main/opt_tvc.test
View File

@ -255,7 +255,7 @@ deallocate prepare stmt;
--echo # use inside out access from tvc rows
let $query= select * from t3 where a in (1,4,10);
let $query= select * from t3 where a in (1,4);
set @@in_predicate_conversion_threshold= default;
eval $query;
eval explain extended $query;

6
mysql-test/main/range.result
View File

@ -1052,6 +1052,7 @@ create table t1 (a int);
insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t2 (a int, key(a));
insert into t2 select 2*(A.a + 10*(B.a + 10*C.a)) from t1 A, t1 B, t1 C;
set in_predicate_conversion_threshold= 2000;
set @a="select * from t2 force index (a) where a NOT IN(0";
select count(*) from (select @a:=concat(@a, ',', a) from t2 ) Z;
count(*)
@ -1062,15 +1063,14 @@ set @b= concat("explain ", @a);
prepare stmt1 from @b;
execute stmt1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 index NULL a 5 NULL 1003 Using where; Using index
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2
3 DERIVED NULL NULL NULL NULL NULL NULL NULL No tables used
1 SIMPLE t2 index a a 5 NULL 1003 Using where; Using index
prepare stmt1 from @a;
execute stmt1;
a
11
13
15
set in_predicate_conversion_threshold= default;
drop table t1, t2;
CREATE TABLE t1 (
id int NOT NULL DEFAULT '0',

4
mysql-test/main/range.test
View File

@ -870,6 +870,8 @@ insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t2 (a int, key(a));
insert into t2 select 2*(A.a + 10*(B.a + 10*C.a)) from t1 A, t1 B, t1 C;
set in_predicate_conversion_threshold= 2000;
set @a="select * from t2 force index (a) where a NOT IN(0";
select count(*) from (select @a:=concat(@a, ',', a) from t2 ) Z;
set @a=concat(@a, ')');
@ -884,6 +886,8 @@ execute stmt1;
prepare stmt1 from @a;
execute stmt1;
set in_predicate_conversion_threshold= default;
drop table t1, t2;
#

6
mysql-test/main/range_mrr_icp.result
View File

@ -1054,6 +1054,7 @@ create table t1 (a int);
insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t2 (a int, key(a));
insert into t2 select 2*(A.a + 10*(B.a + 10*C.a)) from t1 A, t1 B, t1 C;
set in_predicate_conversion_threshold= 2000;
set @a="select * from t2 force index (a) where a NOT IN(0";
select count(*) from (select @a:=concat(@a, ',', a) from t2 ) Z;
count(*)
@ -1064,15 +1065,14 @@ set @b= concat("explain ", @a);
prepare stmt1 from @b;
execute stmt1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 index NULL a 5 NULL 1003 Using where; Using index
2 MATERIALIZED <derived3> ALL NULL NULL NULL NULL 2
3 DERIVED NULL NULL NULL NULL NULL NULL NULL No tables used
1 SIMPLE t2 index a a 5 NULL 1003 Using where; Using index
prepare stmt1 from @a;
execute stmt1;
a
11
13
15
set in_predicate_conversion_threshold= default;
drop table t1, t2;
CREATE TABLE t1 (
id int NOT NULL DEFAULT '0',

57
mysql-test/main/table_value_constr.result
View File

@ -2097,3 +2097,60 @@ v
#
with t as (values (),()) select 1 from t;
ERROR HY000: Row with no elements is not allowed in table value constructor in this context
#
# MDEV-17017: TVC in derived table
#
create table t1 (a int);
insert into t1 values (9), (3), (2);
select * from (values (7), (5), (8), (1), (3), (8), (1)) t;
7
7
5
8
1
3
8
1
explain select * from (values (7), (5), (8), (1), (3), (8), (1)) t;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 7
2 DERIVED NULL NULL NULL NULL NULL NULL NULL No tables used
select * from (values (1,11), (7,77), (3,31), (4,42)) t;
1 11
1 11
7 77
3 31
4 42
explain select * from (values (1,11), (7,77), (3,31), (4,42)) t;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 4
2 DERIVED NULL NULL NULL NULL NULL NULL NULL No tables used
select * from (values (7), (5), (8), (1) union values (3), (8), (1)) t;
7
7
5
8
1
3
explain select * from (values (7), (5), (8), (1) union values (3), (8), (1)) t;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 7
2 DERIVED NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
select * from (values (7), (5), (8), (1) union select * from t1) t;
7
7
5
8
1
9
3
2
explain select * from (values (7), (5), (8), (1) union select * from t1) t;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 7
2 DERIVED NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION t1 ALL NULL NULL NULL NULL 3
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
drop table t1;

29
mysql-test/main/table_value_constr.test
View File

@ -1075,3 +1075,32 @@ DELIMITER ;|
--error ER_EMPTY_ROW_IN_TVC
with t as (values (),()) select 1 from t;
--echo #
--echo # MDEV-17017: TVC in derived table
--echo #
create table t1 (a int);
insert into t1 values (9), (3), (2);
let $q1=
select * from (values (7), (5), (8), (1), (3), (8), (1)) t;
eval $q1;
eval explain $q1;
let $q2=
select * from (values (1,11), (7,77), (3,31), (4,42)) t;
eval $q2;
eval explain $q2;
let $q3=
select * from (values (7), (5), (8), (1) union values (3), (8), (1)) t;
eval $q3;
eval explain $q3;
let $q4=
select * from (values (7), (5), (8), (1) union select * from t1) t;
eval $q4;
eval explain $q4;
drop table t1;

2
sql/sql_tvc.h
View File

@ -50,6 +50,8 @@ public:
have_query_plan(QEP_NOT_PRESENT_YET), explain(0),
select_options(select_options_arg)
{ };
ha_rows get_records() { return lists_of_values.elements; }
bool prepare(THD *thd_arg, SELECT_LEX *sl,
select_result *tmp_result,

2
sql/sql_union.cc
View File

@ -1321,6 +1321,8 @@ bool st_select_lex_unit::optimize()
thd->lex->current_select= lex_select_save;
DBUG_RETURN(TRUE);
}
if (derived)
sl->increase_derived_records(sl->tvc->get_records());
continue;
}
thd->lex->current_select= sl;