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BUG#45174: XOR in subqueries produces differing results in 5.1 and 5.4

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BUG#50019: Wrong result for IN-subquery with materialization
- Fix equality substitution in presense of semi-join materialization, lookup and scan variants
  (started off from fix by Evgen Potemkin, then modified it to work in all cases)
This commit is contained in:
Sergey Petrunya
2010-03-13 23:04:52 +03:00
parent c2924e155e
commit 02e9fa62e7
11 changed files with 356 additions and 54 deletions
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25
mysql-test/r/subselect_mat.result
View File

@ -1219,3 +1219,28 @@ SELECT pk FROM t1 WHERE (b,c,d) IN (SELECT b,c,d FROM t2 WHERE pk > 0);
pk
2
DROP TABLE t1, t2;
#
# BUG#50019: Wrong result for IN-subquery with materialization
#
create table t1(i int);
insert into t1 values (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
create table t2(i int);
insert into t2 values (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
create table t3(i int);
insert into t3 values (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
select * from t1 where t1.i in (select t2.i from t2 join t3 where t2.i + t3.i = 5);
i
1
2
3
4
set @save_optimizer_switch=@@optimizer_switch;
set session optimizer_switch='materialization=off';
select * from t1 where t1.i in (select t2.i from t2 join t3 where t2.i + t3.i = 5);
i
1
2
3
4
set session optimizer_switch=@save_optimizer_switch;
drop table t1, t2, t3;

36
mysql-test/r/subselect_sj.result
View File

@ -871,3 +871,39 @@ id select_type table type possible_keys key key_len ref rows Extra
DROP TABLE t1, t2, t3;
DROP VIEW v2, v3;
# End of Bug#49198
#
# Bug#45174: Incorrectly applied equality propagation caused wrong
# result on a query with a materialized semi-join.
#
CREATE TABLE `t1` (
`pk` int(11) NOT NULL AUTO_INCREMENT,
`varchar_key` varchar(1) NOT NULL,
`varchar_nokey` varchar(1) NOT NULL,
PRIMARY KEY (`pk`),
KEY `varchar_key` (`varchar_key`)
);
INSERT INTO `t1` VALUES (11,'m','m'),(12,'j','j'),(13,'z','z'),(14,'a','a'),(15,'',''),(16,'e','e'),(17,'t','t'),(19,'b','b'),(20,'w','w'),(21,'m','m'),(23,'',''),(24,'w','w'),(26,'e','e'),(27,'e','e'),(28,'p','p');
CREATE TABLE `t2` (
`varchar_nokey` varchar(1) NOT NULL
);
INSERT INTO `t2` VALUES ('v'),('u'),('n'),('l'),('h'),('u'),('n'),('j'),('k'),('e'),('i'),('u'),('n'),('b'),('x'),(''),('q'),('u');
EXPLAIN EXTENDED SELECT varchar_nokey
FROM t2
WHERE ( `varchar_nokey` , `varchar_nokey` ) IN (
SELECT `varchar_key` , `varchar_nokey`
FROM t1
WHERE `varchar_nokey` < 'n' XOR `pk` ) ;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 18 100.00
1 PRIMARY t1 ALL varchar_key NULL NULL NULL 15 100.00 Using where; Materialize
Warnings:
Note 1003 select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_nokey` = `test`.`t1`.`varchar_key`) and ((`test`.`t1`.`varchar_nokey` < 'n') xor `test`.`t1`.`pk`))
SELECT varchar_nokey
FROM t2
WHERE ( `varchar_nokey` , `varchar_nokey` ) IN (
SELECT `varchar_key` , `varchar_nokey`
FROM t1
WHERE `varchar_nokey` < 'n' XOR `pk` ) ;
varchar_nokey
DROP TABLE t1, t2;
# End of the test for bug#45174.

36
mysql-test/r/subselect_sj_jcl6.result
View File

@ -876,6 +876,42 @@ DROP TABLE t1, t2, t3;
DROP VIEW v2, v3;
# End of Bug#49198
#
# Bug#45174: Incorrectly applied equality propagation caused wrong
# result on a query with a materialized semi-join.
#
CREATE TABLE `t1` (
`pk` int(11) NOT NULL AUTO_INCREMENT,
`varchar_key` varchar(1) NOT NULL,
`varchar_nokey` varchar(1) NOT NULL,
PRIMARY KEY (`pk`),
KEY `varchar_key` (`varchar_key`)
);
INSERT INTO `t1` VALUES (11,'m','m'),(12,'j','j'),(13,'z','z'),(14,'a','a'),(15,'',''),(16,'e','e'),(17,'t','t'),(19,'b','b'),(20,'w','w'),(21,'m','m'),(23,'',''),(24,'w','w'),(26,'e','e'),(27,'e','e'),(28,'p','p');
CREATE TABLE `t2` (
`varchar_nokey` varchar(1) NOT NULL
);
INSERT INTO `t2` VALUES ('v'),('u'),('n'),('l'),('h'),('u'),('n'),('j'),('k'),('e'),('i'),('u'),('n'),('b'),('x'),(''),('q'),('u');
EXPLAIN EXTENDED SELECT varchar_nokey
FROM t2
WHERE ( `varchar_nokey` , `varchar_nokey` ) IN (
SELECT `varchar_key` , `varchar_nokey`
FROM t1
WHERE `varchar_nokey` < 'n' XOR `pk` ) ;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 18 100.00
1 PRIMARY t1 ALL varchar_key NULL NULL NULL 15 100.00 Using where; Materialize
Warnings:
Note 1003 select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_nokey` = `test`.`t1`.`varchar_key`) and ((`test`.`t1`.`varchar_nokey` < 'n') xor `test`.`t1`.`pk`))
SELECT varchar_nokey
FROM t2
WHERE ( `varchar_nokey` , `varchar_nokey` ) IN (
SELECT `varchar_key` , `varchar_nokey`
FROM t1
WHERE `varchar_nokey` < 'n' XOR `pk` ) ;
varchar_nokey
DROP TABLE t1, t2;
# End of the test for bug#45174.
#
# BUG#49129: Wrong result with IN-subquery with join_cache_level=6 and firstmatch=off
#
CREATE TABLE t0 (a INT);

16
mysql-test/t/subselect_mat.test
View File

@ -889,3 +889,19 @@ SELECT pk FROM t1 WHERE (a) IN (SELECT a FROM t2 WHERE pk > 0);
SELECT pk FROM t1 WHERE (b,c,d) IN (SELECT b,c,d FROM t2 WHERE pk > 0);
DROP TABLE t1, t2;
--echo #
--echo # BUG#50019: Wrong result for IN-subquery with materialization
--echo #
create table t1(i int);
insert into t1 values (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
create table t2(i int);
insert into t2 values (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
create table t3(i int);
insert into t3 values (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
select * from t1 where t1.i in (select t2.i from t2 join t3 where t2.i + t3.i = 5);
set @save_optimizer_switch=@@optimizer_switch;
set session optimizer_switch='materialization=off';
select * from t1 where t1.i in (select t2.i from t2 join t3 where t2.i + t3.i = 5);
set session optimizer_switch=@save_optimizer_switch;
drop table t1, t2, t3;

39
mysql-test/t/subselect_sj.test
View File

@ -770,3 +770,42 @@ DROP TABLE t1, t2, t3;
DROP VIEW v2, v3;
--echo # End of Bug#49198
--echo #
--echo # Bug#45174: Incorrectly applied equality propagation caused wrong
--echo # result on a query with a materialized semi-join.
--echo #
CREATE TABLE `t1` (
`pk` int(11) NOT NULL AUTO_INCREMENT,
`varchar_key` varchar(1) NOT NULL,
`varchar_nokey` varchar(1) NOT NULL,
PRIMARY KEY (`pk`),
KEY `varchar_key` (`varchar_key`)
);
INSERT INTO `t1` VALUES (11,'m','m'),(12,'j','j'),(13,'z','z'),(14,'a','a'),(15,'',''),(16,'e','e'),(17,'t','t'),(19,'b','b'),(20,'w','w'),(21,'m','m'),(23,'',''),(24,'w','w'),(26,'e','e'),(27,'e','e'),(28,'p','p');
CREATE TABLE `t2` (
`varchar_nokey` varchar(1) NOT NULL
);
INSERT INTO `t2` VALUES ('v'),('u'),('n'),('l'),('h'),('u'),('n'),('j'),('k'),('e'),('i'),('u'),('n'),('b'),('x'),(''),('q'),('u');
EXPLAIN EXTENDED SELECT varchar_nokey
FROM t2
WHERE ( `varchar_nokey` , `varchar_nokey` ) IN (
SELECT `varchar_key` , `varchar_nokey`
FROM t1
WHERE `varchar_nokey` < 'n' XOR `pk` ) ;
SELECT varchar_nokey
FROM t2
WHERE ( `varchar_nokey` , `varchar_nokey` ) IN (
SELECT `varchar_key` , `varchar_nokey`
FROM t1
WHERE `varchar_nokey` < 'n' XOR `pk` ) ;
DROP TABLE t1, t2;
--echo # End of the test for bug#45174.

2
sql/item.cc
View File

@ -4761,7 +4761,7 @@ Item *Item_field::replace_equal_field(uchar *arg)
return this;
return const_item;
}
Item_field *subst= item_equal->get_first();
Item_field *subst= item_equal->get_first(this);
if (subst && field->table != subst->field->table && !field->eq(subst->field))
return subst;
}

127
sql/item_cmpfunc.cc
View File

@ -5369,7 +5369,7 @@ longlong Item_equal::val_int()
void Item_equal::fix_length_and_dec()
{
Item *item= get_first();
Item *item= get_first(NULL);
eval_item= cmp_item::get_comparator(item->result_type(),
item->collation.collation);
}
@ -5432,3 +5432,128 @@ void Item_equal::print(String *str, enum_query_type query_type)
str->append(')');
}
/*
@brief Get the first equal field of multiple equality.
@param[in] field the field to get equal field to
@details Get the first field of multiple equality that is equal to the
given field. In order to make semi-join materialization strategy work
correctly we can't propagate equal fields from upper select to a
materialized semi-join.
Thus the fields is returned according to following rules:
1) If the given field belongs to a semi-join then the first field in
multiple equality which belong to the same semi-join is returned.
Otherwise NULL is returned.
2) If the given field doesn't belong to a semi-join then
the first field in the multiple equality that doesn't belong to any
semi-join is returned.
If all fields in the equality are belong to semi-join(s) then NULL
is returned.
3) If no field is given then the first field in the multiple equality
is returned without regarding whether it belongs to a semi-join or not.
@retval Found first field in the multiple equality.
@retval 0 if no field found.
*/
Item_field* Item_equal::get_first(Item_field *field)
{
List_iterator<Item_field> it(fields);
Item_field *item;
JOIN_TAB *field_tab;
if (!field)
return fields.head();
/*
Of all equal fields, return the first one we can use. Normally, this is the
field which belongs to the table that is the first in the join order.
There is one exception to this: When semi-join materialization strategy is
used, and the given field belongs to a table within the semi-join nest, we
must pick the first field in the semi-join nest.
Example: suppose we have a join order:
ot1 ot2 SJ-Mat(it1 it2 it3) ot3
and equality ot2.col = it1.col = it2.col
If we're looking for best substitute for 'it2.col', we should pick it1.col
and not ot2.col.
eliminate_item_equal() also has code that deals with equality substitution
in presense of SJM nests.
*/
field_tab= field->field->table->reginfo.join_tab;
TABLE_LIST *emb_nest= field->field->table->pos_in_table_list->embedding;
if (emb_nest && emb_nest->sj_mat_info && emb_nest->sj_mat_info->is_used)
{
/*
It's a field from an materialized semi-join. We can substitute it only
for a field from the same semi-join.
*/
JOIN_TAB *first;
JOIN *join= field_tab->join;
uint tab_idx= field_tab - field_tab->join->join_tab;
/* Find the first table of this semi-join nest */
for (uint i= tab_idx; i != join->const_tables; i--)
{
if (join->join_tab[i].table->map & emb_nest->sj_inner_tables)
first= join->join_tab + i;
else
// Found first tab that doesn't belong to current SJ.
break;
}
/* Find an item to substitute for. */
while ((item= it++))
{
if (item->field->table->reginfo.join_tab >= first)
{
/*
If we found given field then return NULL to avoid unnecessary
substitution.
*/
return (item != field) ? item : NULL;
}
}
}
else
{
#if 0
/*
The field is not in SJ-Materialization nest. We must return the first
field that's not embedded in a SJ-Materialization nest.
Example: suppose we have a join order:
SJ-Mat(it1 it2) ot1 ot2
and equality ot2.col = ot1.col = it2.col
If we're looking for best substitute for 'ot2.col', we should pick ot1.col
and not it2.col, because when we run a join between ot1 and ot2
execution of SJ-Mat(...) has already finished and we can't rely on the
value of it*.*.
psergey-fix-fix: ^^ THAT IS INCORRECT ^^. Pick the first, whatever that
is.
*/
while ((item= it++))
{
TABLE_LIST *emb_nest= item->field->table->pos_in_table_list->embedding;
if (!emb_nest || !emb_nest->sj_mat_info ||
!emb_nest->sj_mat_info->is_used)
{
return item;
}
}
#endif
return fields.head();
}
// Shouldn't get here.
DBUG_ASSERT(0);
return NULL;
}

2
sql/item_cmpfunc.h
View File

@ -1589,7 +1589,7 @@ public:
void add(Item_field *f);
uint members();
bool contains(Field *field);
Item_field* get_first() { return fields.head(); }
Item_field* get_first(Item_field *field);
uint n_fields() { return fields.elements; }
void merge(Item_equal *item);
void update_const();

2
sql/opt_subselect.cc
View File

@ -2159,6 +2159,8 @@ void fix_semijoin_strategies_for_picked_join_order(JOIN *join)
if (tablenr != first)
pos->sj_strategy= SJ_OPT_NONE;
remaining_tables |= s->table->map;
//s->sj_strategy= pos->sj_strategy;
join->join_tab[first].sj_strategy= join->best_positions[first].sj_strategy;
}
}

116
sql/sql_select.cc
View File

@ -8867,6 +8867,15 @@ static int compare_fields_by_table_order(Item_field *field1,
}
static TABLE_LIST* embedding_sjm(Item_field *item_field)
{
TABLE_LIST *nest= item_field->field->table->pos_in_table_list->embedding;
if (nest && nest->sj_mat_info && nest->sj_mat_info->is_used)
return nest;
else
return NULL;
}
/**
Generate minimal set of simple equalities equivalent to a multiple equality.
@ -8901,6 +8910,23 @@ static int compare_fields_by_table_order(Item_field *field1,
If cond is equal to 0, then not more then one equality is generated
and a pointer to it is returned as the result of the function.
Equality substutution and semi-join materialization nests:
In case join order looks like this:
outer_tbl1 outer_tbl2 SJM (inner_tbl1 inner_tbl2) outer_tbl3
We must not construct equalities like
outer_tbl1.col = inner_tbl1.col
because they would get attached to inner_tbl1 and will get evaluated
during materialization phase, when we don't have current value of
outer_tbl1.col.
Item_equal::get_first() also takes similar measures for dealing with
equality substitution in presense of SJM nests.
@return
- The condition with generated simple equalities or
a pointer to the simple generated equality, if success.
@ -8917,18 +8943,44 @@ Item *eliminate_item_equal(COND *cond, COND_EQUAL *upper_levels,
Item *item_const= item_equal->get_const();
Item_equal_iterator it(*item_equal);
Item *head;
TABLE_LIST *current_sjm= NULL;
Item *current_sjm_head= NULL;
/*
Pick the "head" item: the constant one or the first in the join order
that's not inside some SJM nest.
*/
if (item_const)
head= item_const;
else
{
head= item_equal->get_first();
TABLE_LIST *emb_nest;
Item_field *item_field;
head= item_field= item_equal->get_first(NULL);
it++;
if ((emb_nest= embedding_sjm(item_field)))
{
current_sjm= emb_nest;
current_sjm_head= head;
}
}
Item_field *item_field;
/*
For each other item, generate "item=head" equality (except the tables that
are within SJ-Materialization nests, for those "head" is defined
differently)
*/
while ((item_field= it++))
{
Item_equal *upper= item_field->find_item_equal(upper_levels);
Item_field *item= item_field;
TABLE_LIST *field_sjm= embedding_sjm(item_field);
/*
Check if "item_field=head" equality is already guaranteed to be true
on upper AND-levels.
*/
if (upper)
{
if (item_const && upper->get_const())
@ -8943,65 +8995,29 @@ Item *eliminate_item_equal(COND *cond, COND_EQUAL *upper_levels,
}
}
}
if (item == item_field)
bool produce_equality= test(item == item_field);
if (!item_const && field_sjm && field_sjm != current_sjm)
{
/* Entering an SJM nest */
current_sjm_head= item_field;
if (!field_sjm->sj_mat_info->is_sj_scan)
produce_equality= FALSE;
}
if (produce_equality)
{
if (eq_item)
eq_list.push_back(eq_item);
/*
item_field might refer to a table that is within a semi-join
materialization nest. In that case, the join order looks like this:
outer_tbl1 outer_tbl2 SJM (inner_tbl1 inner_tbl2) outer_tbl3
eq_item= new Item_func_eq(item_field, current_sjm? current_sjm_head: head);
We must not construct equalities like
outer_tbl1.col = inner_tbl1.col
because they would get attached to inner_tbl1 and will get evaluated
during materialization phase, when we don't have current value of
outer_tbl1.col.
*/
TABLE_LIST *emb_nest=
item_field->field->table->pos_in_table_list->embedding;
if (!item_const && emb_nest && emb_nest->sj_mat_info &&
emb_nest->sj_mat_info->is_used)
{
/*
Find the first equal expression that refers to a table that is
within the semijoin nest. If we can't find it, do nothing
*/
List_iterator<Item_field> fit(item_equal->fields);
Item_field *head_in_sjm;
bool found= FALSE;
while ((head_in_sjm= fit++))
{
if (head_in_sjm->used_tables() & emb_nest->sj_inner_tables)
{
if (head_in_sjm == item_field)
{
/* This is the first table inside the semi-join*/
eq_item= new Item_func_eq(item_field, head);
/* Tell make_cond_for_table don't use this. */
eq_item->marker=3;
}
else
{
eq_item= new Item_func_eq(item_field, head_in_sjm);
found= TRUE;
}
break;
}
}
if (!found)
continue;
}
else
eq_item= new Item_func_eq(item_field, head);
if (!eq_item)
return 0;
eq_item->set_cmp_func();
eq_item->quick_fix_field();
}
current_sjm= field_sjm;
}
if (!cond && !eq_list.head())

7
sql/sql_select.h
View File

@ -279,6 +279,13 @@ typedef struct st_join_table {
/* NestedOuterJoins: Bitmap of nested joins this table is part of */
nested_join_map embedding_map;
/*
Semi-join strategy to be used for this join table. This is a copy of
POSITION::sj_strategy field. This field is set up by the
fix_semijion_strategies_for_picked_join_order.
*/
uint sj_strategy;
void cleanup();
inline bool is_using_loose_index_scan()
{