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Bug#23800: Outer fields in correlated subqueries is used in a temporary table

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created for sorting.

Any outer reference in a subquery was represented by an Item_field object.
If the outer select employs a temporary table all such fields should be
replaced with fields from that temporary table in order to point to the 
actual data. This replacement wasn't done and that resulted in a wrong
subquery evaluation and a wrong result of the whole query.

Now any outer field is represented by two objects - Item_field placed in the
outer select and Item_outer_ref in the subquery. Item_field object is
processed as a normal field and the reference to it is saved in the
ref_pointer_array. Thus the Item_outer_ref is always references the correct
field. The original field is substituted for a reference in the
Item_field::fix_outer_field() function.

New function called fix_inner_refs() is added to fix fields referenced from
inner selects and to fix references (Item_ref objects) to these fields.

The new Item_outer_ref class is a descendant of the Item_direct_ref class.
It additionally stores a reference to the original field and designed to
behave more like a field.
This commit is contained in:
evgen@moonbone.local
2007-02-21 23:00:32 +03:00
parent 674868dabf
commit 9a233742b8
11 changed files with 290 additions and 41 deletions
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3
sql/sql_lex.h
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@@ -547,7 +547,8 @@ public:
bool braces; /* SELECT ... UNION (SELECT ... ) <- this braces */
/* TRUE when having fix field called in processing of this SELECT */
bool having_fix_field;
/* List of references to fields referenced from inner selects */
List<Item_outer_ref> inner_refs_list;
/* Number of Item_sum-derived objects in this SELECT */
uint n_sum_items;
/* Number of Item_sum-derived objects in children and descendant SELECTs */