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Bug#11766675 - 59839: Aggregation followed by subquery yields wrong result

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The loop that was looping over subqueries' references to outer field used a
local boolean variable to tell whether the field was grouped or not. But the
implementor failed to reset the variable after each iteration. Thus a field
that was not directly aggregated appeared to be.

Fixed by resetting the variable upon each new iteration.
This commit is contained in:
Martin Hansson 2011-02-18 11:50:06 +01:00
parent cc7b3de9fc
commit 61b256177b
3 changed files with 108 additions and 31 deletions
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36
mysql-test/r/group_by.result
View File

@ -1855,4 +1855,40 @@ ON 1 WHERE t2.f1 > 1 GROUP BY t2.f1;
COUNT(*)
2
DROP TABLE t1;
#
# Bug#59839: Aggregation followed by subquery yields wrong result
#
CREATE TABLE t1 (
a INT,
b INT,
c INT,
KEY (a, b)
);
INSERT INTO t1 VALUES
( 1, 1, 1 ),
( 1, 2, 2 ),
( 1, 3, 3 ),
( 1, 4, 6 ),
( 1, 5, 5 ),
( 1, 9, 13 ),
( 2, 1, 6 ),
( 2, 2, 7 ),
( 2, 3, 8 );
EXPLAIN
SELECT a, AVG(t1.b),
(SELECT t11.c FROM t1 t11 WHERE t11.a = t1.a AND t11.b = AVG(t1.b)) AS t11c,
(SELECT t12.c FROM t1 t12 WHERE t12.a = t1.a AND t12.b = AVG(t1.b)) AS t12c
FROM t1 GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index NULL a 10 NULL 9 Using index
3 DEPENDENT SUBQUERY t12 ref a a 10 func,func 2 Using where
2 DEPENDENT SUBQUERY t11 ref a a 10 func,func 2 Using where
SELECT a, AVG(t1.b),
(SELECT t11.c FROM t1 t11 WHERE t11.a = t1.a AND t11.b = AVG(t1.b)) AS t11c,
(SELECT t12.c FROM t1 t12 WHERE t12.a = t1.a AND t12.b = AVG(t1.b)) AS t12c
FROM t1 GROUP BY a;
a AVG(t1.b) t11c t12c
1 4.0000 6 6
2 2.0000 7 7
DROP TABLE t1;
# End of 5.1 tests

37
mysql-test/t/group_by.test
View File

@ -1247,4 +1247,41 @@ ON 1 WHERE t2.f1 > 1 GROUP BY t2.f1;
DROP TABLE t1;
--echo #
--echo # Bug#59839: Aggregation followed by subquery yields wrong result
--echo #
CREATE TABLE t1 (
a INT,
b INT,
c INT,
KEY (a, b)
);
INSERT INTO t1 VALUES
( 1, 1, 1 ),
( 1, 2, 2 ),
( 1, 3, 3 ),
( 1, 4, 6 ),
( 1, 5, 5 ),
( 1, 9, 13 ),
( 2, 1, 6 ),
( 2, 2, 7 ),
( 2, 3, 8 );
EXPLAIN
SELECT a, AVG(t1.b),
(SELECT t11.c FROM t1 t11 WHERE t11.a = t1.a AND t11.b = AVG(t1.b)) AS t11c,
(SELECT t12.c FROM t1 t12 WHERE t12.a = t1.a AND t12.b = AVG(t1.b)) AS t12c
FROM t1 GROUP BY a;
SELECT a, AVG(t1.b),
(SELECT t11.c FROM t1 t11 WHERE t11.a = t1.a AND t11.b = AVG(t1.b)) AS t11c,
(SELECT t12.c FROM t1 t12 WHERE t12.a = t1.a AND t12.b = AVG(t1.b)) AS t12c
FROM t1 GROUP BY a;
DROP TABLE t1;
--echo # End of 5.1 tests

66
sql/sql_select.cc
View File

@ -278,61 +278,65 @@ bool handle_select(THD *thd, LEX *lex, select_result *result,
}
/*
/**
Fix fields referenced from inner selects.
SYNOPSIS
fix_inner_refs()
thd Thread handle
all_fields List of all fields used in select
select Current select
ref_pointer_array Array of references to Items used in current select
group_list GROUP BY list (is NULL by default)
@param thd Thread handle
@param all_fields List of all fields used in select
@param select Current select
@param ref_pointer_array Array of references to Items used in current select
@param group_list GROUP BY list (is NULL by default)
DESCRIPTION
The function serves 3 purposes - adds fields referenced from inner
selects to the current select list, resolves which class to use
to access referenced item (Item_ref of Item_direct_ref) and fixes
references (Item_ref objects) to these fields.
@details
The function serves 3 purposes
If a field isn't already in the select list and the ref_pointer_array
- adds fields referenced from inner query blocks to the current select list
- Decides which class to use to reference the items (Item_ref or
Item_direct_ref)
- fixes references (Item_ref objects) to these fields.
If a field isn't already on the select list and the ref_pointer_array
is provided then it is added to the all_fields list and the pointer to
it is saved in the ref_pointer_array.
The class to access the outer field is determined by the following rules:
1. If the outer field isn't used under an aggregate function
then the Item_ref class should be used.
2. If the outer field is used under an aggregate function and this
function is aggregated in the select where the outer field was
resolved or in some more inner select then the Item_direct_ref
class should be used.
Also it should be used if we are grouping by a subquery containing
the outer field.
-#. If the outer field isn't used under an aggregate function then the
Item_ref class should be used.
-#. If the outer field is used under an aggregate function and this
function is, in turn, aggregated in the query block where the outer
field was resolved or some query nested therein, then the
Item_direct_ref class should be used. Also it should be used if we are
grouping by a subquery containing the outer field.
The resolution is done here and not at the fix_fields() stage as
it can be done only after sum functions are fixed and pulled up to
selects where they are have to be aggregated.
it can be done only after aggregate functions are fixed and pulled up to
selects where they are to be aggregated.
When the class is chosen it substitutes the original field in the
Item_outer_ref object.
After this we proceed with fixing references (Item_outer_ref objects) to
this field from inner subqueries.
RETURN
TRUE an error occured
FALSE ok
*/
@return Status
@retval true An error occured.
@retval false OK.
*/
bool
fix_inner_refs(THD *thd, List<Item> &all_fields, SELECT_LEX *select,
Item **ref_pointer_array, ORDER *group_list)
{
Item_outer_ref *ref;
bool res= FALSE;
bool direct_ref= FALSE;
List_iterator<Item_outer_ref> ref_it(select->inner_refs_list);
while ((ref= ref_it++))
{
bool direct_ref= false;
Item *item= ref->outer_ref;
Item **item_ref= ref->ref;
Item_ref *new_ref;
@ -404,7 +408,7 @@ fix_inner_refs(THD *thd, List<Item> &all_fields, SELECT_LEX *select,
return TRUE;
thd->used_tables|= item->used_tables();
}
return res;
return false;
}
/**