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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.


sql/item.cc:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  Now all outer fields are substituted with references to them (Item_outer_ref objects)
  in the Item_field::fix_outer_field() function.
  The original field is saved in the Item_outer_ref object.
sql/item.h:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  Added the Item_outer_ref class.
sql/mysql_priv.h:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  Added the fix_inner_refs() function prototype.
sql/sql_delete.cc:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  Added call to the fix_inner_refs() function.
sql/sql_select.cc:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  The new function called fix_inner_refs() is added.
mysql-test/r/subselect.result:
  Added a test case for bug#23800: Correlated sub query returning incorrect results when
  operated upon.
sql/sql_update.cc:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  Added call to the fix_inner_refs() function.
mysql-test/r/subselect3.result:
  Corrected test cases result after fix for bug#23800: Correlated sub query returning
  incorrect results when operated upon.
mysql-test/t/subselect.test:
  Added a test case for bug#23800: Correlated sub query returning incorrect results when
  operated upon.
sql/sql_lex.cc:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  Added cleanup of the inner_refs_list.
sql/sql_lex.h:
  Bug#23800: Correlated sub query returning incorrect results when operated upon.
  The inner_refs_list is added to the SELECT_LEX class.
This commit is contained in:
unknown 2007-02-21 23:00:32 +03:00
commit f8855142d7
11 changed files with 290 additions and 41 deletions
Download patch file Download diff file Expand all files Collapse all files

80
sql/item.cc
View file

@ -1609,7 +1609,7 @@ void Item_ident_for_show::make_field(Send_field *tmp_field)
Item_field::Item_field(Field *f)
:Item_ident(0, NullS, *f->table_name, f->field_name),
item_equal(0), no_const_subst(0),
have_privileges(0), any_privileges(0)
have_privileges(0), any_privileges(0), fixed_as_field(0)
{
set_field(f);
/*
@ -1623,7 +1623,7 @@ Item_field::Item_field(THD *thd, Name_resolution_context *context_arg,
Field *f)
:Item_ident(context_arg, f->table->s->db, *f->table_name, f->field_name),
item_equal(0), no_const_subst(0),
have_privileges(0), any_privileges(0)
have_privileges(0), any_privileges(0), fixed_as_field(0)
{
/*
We always need to provide Item_field with a fully qualified field
@ -1662,7 +1662,7 @@ Item_field::Item_field(Name_resolution_context *context_arg,
const char *field_name_arg)
:Item_ident(context_arg, db_arg,table_name_arg,field_name_arg),
field(0), result_field(0), item_equal(0), no_const_subst(0),
have_privileges(0), any_privileges(0)
have_privileges(0), any_privileges(0), fixed_as_field(0)
{
collation.set(DERIVATION_IMPLICIT);
}
@ -1675,7 +1675,8 @@ Item_field::Item_field(THD *thd, Item_field *item)
item_equal(item->item_equal),
no_const_subst(item->no_const_subst),
have_privileges(item->have_privileges),
any_privileges(item->any_privileges)
any_privileges(item->any_privileges),
fixed_as_field(item->fixed_as_field)
{
collation.set(DERIVATION_IMPLICIT);
}
@ -3484,8 +3485,46 @@ Item_field::fix_outer_field(THD *thd, Field **from_field, Item **reference)
}
if (*from_field != view_ref_found)
{
prev_subselect_item->used_tables_cache|= (*from_field)->table->map;
prev_subselect_item->const_item_cache= 0;
if (!last_checked_context->select_lex->having_fix_field &&
!fixed_as_field)
{
Item_outer_ref *rf;
Query_arena *arena= 0, backup;
/*
Each outer field is replaced for an Item_outer_ref object.
This is done in order to get correct results when the outer
select employs a temporary table.
The original fields are saved in the inner_fields_list of the
outer select. This list is created by the following reasons:
1. We can't add field items to the outer select list directly
because the outer select hasn't been fully fixed yet.
2. We need a location to refer to in the Item_ref object
so the inner_fields_list is used as such temporary
reference storage.
The new Item_outer_ref object replaces the original field and is
also saved in the inner_refs_list of the outer select. Here
it is only created. It can be fixed only after the original
field has been fixed and this is done in the fix_inner_refs()
function.
*/
set_field(*from_field);
arena= thd->activate_stmt_arena_if_needed(&backup);
rf= new Item_outer_ref(context, this);
if (!rf)
{
if (arena)
thd->restore_active_arena(arena, &backup);
return -1;
}
*reference= rf;
select->inner_refs_list.push_back(rf);
if (arena)
thd->restore_active_arena(arena, &backup);
fixed_as_field= 1;
}
if (thd->lex->in_sum_func &&
thd->lex->in_sum_func->nest_level ==
thd->lex->current_select->nest_level)
@ -3612,7 +3651,7 @@ Item_field::fix_outer_field(THD *thd, Field **from_field, Item **reference)
{
mark_as_dependent(thd, last_checked_context->select_lex,
context->select_lex,
this, this);
this, (Item_ident*)*reference);
if (last_checked_context->select_lex->having_fix_field)
{
Item_ref *rf;
@ -4818,8 +4857,7 @@ Item_ref::Item_ref(Name_resolution_context *context_arg,
/*
This constructor used to create some internals references over fixed items
*/
DBUG_ASSERT(ref != 0);
if (*ref && (*ref)->fixed)
if (ref && *ref && (*ref)->fixed)
set_properties();
}
@ -5119,7 +5157,7 @@ void Item_ref::print(String *str)
if (ref)
{
if ((*ref)->type() != Item::CACHE_ITEM && ref_type() != VIEW_REF &&
name && alias_name_used)
ref_type() != OUTER_REF && name && alias_name_used)
{
THD *thd= current_thd;
append_identifier(thd, str, name, (uint) strlen(name));
@ -5367,7 +5405,7 @@ bool Item_direct_ref::get_date(TIME *ltime,uint fuzzydate)
/*
Prepare referenced view viewld then call usual Item_direct_ref::fix_fields
Prepare referenced field then call usual Item_direct_ref::fix_fields
SYNOPSIS
Item_direct_view_ref::fix_fields()
@ -5390,6 +5428,30 @@ bool Item_direct_view_ref::fix_fields(THD *thd, Item **reference)
return Item_direct_ref::fix_fields(thd, reference);
}
/*
Prepare referenced outer field then call usual Item_direct_ref::fix_fields
SYNOPSIS
Item_outer_ref::fix_fields()
thd thread handler
reference reference on reference where this item stored
RETURN
FALSE OK
TRUE Error
*/
bool Item_outer_ref::fix_fields(THD *thd, Item **reference)
{
DBUG_ASSERT(*ref);
/* outer_field->check_cols() will be made in Item_direct_ref::fix_fields */
outer_field->fixed_as_field= 1;
if (!outer_field->fixed &&
(outer_field->fix_fields(thd, reference)))
return TRUE;
return Item_direct_ref::fix_fields(thd, reference);
}
/*
Compare two view column references for equality.