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Bug#27321: Wrong subquery result in a grouping select.

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The Item_outer_ref class based on the Item_direct_ref class was always used
to represent an outer field. But if the outer select is a grouping one and the 
outer field isn't under an aggregate function which is aggregated in that
outer select an Item_ref object should be used to represent such a field.
If the outer select in which the outer field is resolved isn't grouping then
the Item_field class should be used to represent such a field.
This logic also should be used for an outer field resolved through its alias
name.

Now the Item_field::fix_outer_field() uses Item_outer_field objects to
represent aliased and non-aliased outer fields for grouping outer selects
only.
Now the fix_inner_refs() function chooses which class to use to access outer
field - the Item_ref or the Item_direct_ref. An object of the chosen class
substitutes the original field in the Item_outer_ref object.
The direct_ref and the found_in_select_list fields were added to the
Item_outer_ref class.
This commit is contained in:
evgen@moonbone.local
2007-04-15 08:31:34 +04:00
parent ce9cc47a73
commit 3113ce6383
8 changed files with 248 additions and 92 deletions
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92
sql/sql_select.cc
View File

@ -278,15 +278,30 @@ bool handle_select(THD *thd, LEX *lex, select_result *result,
ref_pointer_array Array of references to Items used in current select
DESCRIPTION
The function fixes fields referenced from inner selects and
also fixes references (Item_ref objects) to these fields. Each field
is fixed as a usual hidden field of the current select - it is added
to the all_fields list and the pointer to it is saved in the
ref_pointer_array if latter is provided.
After the field has been fixed we proceed with fixing references
(Item_ref objects) to this field from inner subqueries. If the
ref_pointer_array is provided then Item_ref objects is set to
reference element in that array with the pointer to the field.
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.
If a field isn't already in 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.
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.
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
@ -299,33 +314,64 @@ fix_inner_refs(THD *thd, List<Item> &all_fields, SELECT_LEX *select,
{
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++))
{
Item_field *item= ref->outer_field;
Item *item= ref->outer_ref;
Item **item_ref= ref->ref;
Item_ref *new_ref;
/*
TODO: this field item already might be present in the select list.
In this case instead of adding new field item we could use an
existing one. The change will lead to less operations for copying fields,
smaller temporary tables and less data passed through filesort.
*/
if (ref_pointer_array)
if (ref_pointer_array && !ref->found_in_select_list)
{
int el= all_fields.elements;
ref_pointer_array[el]= (Item*)item;
ref_pointer_array[el]= item;
/* Add the field item to the select list of the current select. */
all_fields.push_front((Item*)item);
all_fields.push_front(item);
/*
If it's needed reset each Item_ref item that refers this field with
a new reference taken from ref_pointer_array.
*/
ref->ref= ref_pointer_array + el;
item_ref= ref_pointer_array + el;
}
if (!ref->fixed && ref->fix_fields(thd, 0))
if (ref->in_sum_func)
{
res= TRUE;
break;
Item_sum *sum_func;
if (ref->in_sum_func->nest_level > select->nest_level)
direct_ref= TRUE;
else
{
for (sum_func= ref->in_sum_func; sum_func &&
sum_func->aggr_level >= select->nest_level;
sum_func= sum_func->in_sum_func)
{
if (sum_func->aggr_level == select->nest_level)
{
direct_ref= TRUE;
break;
}
}
}
}
new_ref= direct_ref ?
new Item_direct_ref(ref->context, item_ref, ref->field_name,
ref->table_name, ref->alias_name_used) :
new Item_ref(ref->context, item_ref, ref->field_name,
ref->table_name, ref->alias_name_used);
if (!new_ref)
return TRUE;
ref->outer_ref= new_ref;
ref->ref= &ref->outer_ref;
if (!ref->fixed && ref->fix_fields(thd, 0))
return TRUE;
thd->used_tables|= item->used_tables();
}
return res;
@ -478,10 +524,6 @@ JOIN::prepare(Item ***rref_pointer_array,
if (having && having->with_sum_func)
having->split_sum_func2(thd, ref_pointer_array, all_fields,
&having, TRUE);
if (select_lex->inner_refs_list.elements &&
fix_inner_refs(thd, all_fields, select_lex, ref_pointer_array))
DBUG_RETURN(-1);
if (select_lex->inner_sum_func_list)
{
Item_sum *end=select_lex->inner_sum_func_list;
@ -494,6 +536,10 @@ JOIN::prepare(Item ***rref_pointer_array,
} while (item_sum != end);
}
if (select_lex->inner_refs_list.elements &&
fix_inner_refs(thd, all_fields, select_lex, ref_pointer_array))
DBUG_RETURN(-1);
if (setup_ftfuncs(select_lex)) /* should be after having->fix_fields */
DBUG_RETURN(-1);
@ -5214,7 +5260,9 @@ get_store_key(THD *thd, KEYUSE *keyuse, table_map used_tables,
}
else if (keyuse->val->type() == Item::FIELD_ITEM ||
(keyuse->val->type() == Item::REF_ITEM &&
((Item_ref*)keyuse->val)->ref_type() == Item_ref::OUTER_REF) )
((Item_ref*)keyuse->val)->ref_type() == Item_ref::OUTER_REF &&
(*(Item_ref**)((Item_ref*)keyuse->val)->ref)->ref_type() ==
Item_ref::DIRECT_REF) )
return new store_key_field(thd,
key_part->field,
key_buff + maybe_null,