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Fixed bug#16861: User defined variable can have a wrong value if a tmp table was

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used.

Sorting by RAND() uses a temporary table in order to get a correct results.
User defined variable was set during filling the temporary table and later
on it is substituted for its value from the temporary table. Due to this
it contains the last value stored in the temporary table.

Now if the result_field is set for the Item_func_set_user_var object it 
updates variable from the result_field value when being sent to a client.

The Item_func_set_user_var::check() now accepts a use_result_field
parameter. Depending on its value the result_field or the args[0] is used
to get current value.


mysql-test/r/user_var.result:
  Added a test case for bug#16861: User defined variable can have a wrong value if a tmp table was used.
mysql-test/t/user_var.test:
  Added a test case for bug#16861: User defined variable can have a wrong value if a tmp table was used.
sql/item_func.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Now if the result_field is set for the Item_func_set_user_var object it 
  updates variable from the result_field value when being sent to a client.
  
  The Item_func_set_user_var::check() now accepts a use_result_field
  parameter. Depending on its value the result_field or the args[0] is used
  to get current value.
sql/item_func.h:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Added a new SUSERVAR_FUNC function type.
  Updated the Item_func_set_user_var::check() function declaration.
  Added the Item_func_set_user_var::send() member function.
sql/set_var.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Modified to use updated Item_func_set_user_var::check() function.
sql/sql_class.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Modified to use updated Item_func_set_user_var::check() function.
sql/sql_select.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Now an Item_func_set_user_var object isn't substituted for an Item_field object after filling a temporary table.
This commit is contained in:
unknown 2006-08-22 17:37:41 +04:00
parent 6071b686b1
commit c623e54fb8
7 changed files with 58 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
mysql-test/r/user_var.result
View File

@ -292,3 +292,12 @@ SELECT @a;
@a
18446744071710965857
drop table bigfailure;
create table t1(f1 int, f2 int);
insert into t1 values (1,2),(2,3),(3,1);
select @var:=f2 from t1 group by f1 order by f2 desc limit 1;
@var:=f2
3
select @var;
@var
3
drop table t1;

10
mysql-test/t/user_var.test
View File

@ -202,3 +202,13 @@ SET @a := (select * from bigfailure where afield = (SELECT afield FROM bigfailur
SELECT @a;
drop table bigfailure;
#
# Bug#16861: User defined variable can have a wrong value if a tmp table was
# used.
#
create table t1(f1 int, f2 int);
insert into t1 values (1,2),(2,3),(3,1);
select @var:=f2 from t1 group by f1 order by f2 desc limit 1;
select @var;
drop table t1;

42
sql/item_func.cc
View File

@ -548,7 +548,7 @@ void Item_func::signal_divide_by_null()
Item *Item_func::get_tmp_table_item(THD *thd)
{
if (!with_sum_func && !const_item())
if (!with_sum_func && !const_item() && functype() != SUSERVAR_FUNC)
return new Item_field(result_field);
return copy_or_same(thd);
}
@ -3719,30 +3719,38 @@ my_decimal *user_var_entry::val_decimal(my_bool *null_value, my_decimal *val)
*/
bool
Item_func_set_user_var::check()
Item_func_set_user_var::check(bool use_result_field)
{
DBUG_ENTER("Item_func_set_user_var::check");
if (use_result_field)
DBUG_ASSERT(result_field);
switch (cached_result_type) {
case REAL_RESULT:
{
save_result.vreal= args[0]->val_real();
save_result.vreal= use_result_field ? result_field->val_real() :
args[0]->val_real();
break;
}
case INT_RESULT:
{
save_result.vint= args[0]->val_int();
unsigned_flag= args[0]->unsigned_flag;
save_result.vint= use_result_field ? result_field->val_int() :
args[0]->val_int();
unsigned_flag= use_result_field ? ((Field_num*)result_field)->unsigned_flag:
args[0]->unsigned_flag;
break;
}
case STRING_RESULT:
{
save_result.vstr= args[0]->val_str(&value);
save_result.vstr= use_result_field ? result_field->val_str(&value) :
args[0]->val_str(&value);
break;
}
case DECIMAL_RESULT:
{
save_result.vdec= args[0]->val_decimal(&decimal_buff);
save_result.vdec= use_result_field ?
result_field->val_decimal(&decimal_buff) :
args[0]->val_decimal(&decimal_buff);
break;
}
case ROW_RESULT:
@ -3828,7 +3836,7 @@ Item_func_set_user_var::update()
double Item_func_set_user_var::val_real()
{
DBUG_ASSERT(fixed == 1);
check();
check(0);
update(); // Store expression
return entry->val_real(&null_value);
}
@ -3836,7 +3844,7 @@ double Item_func_set_user_var::val_real()
longlong Item_func_set_user_var::val_int()
{
DBUG_ASSERT(fixed == 1);
check();
check(0);
update(); // Store expression
return entry->val_int(&null_value);
}
@ -3844,7 +3852,7 @@ longlong Item_func_set_user_var::val_int()
String *Item_func_set_user_var::val_str(String *str)
{
DBUG_ASSERT(fixed == 1);
check();
check(0);
update(); // Store expression
return entry->val_str(&null_value, str, decimals);
}
@ -3853,7 +3861,7 @@ String *Item_func_set_user_var::val_str(String *str)
my_decimal *Item_func_set_user_var::val_decimal(my_decimal *val)
{
DBUG_ASSERT(fixed == 1);
check();
check(0);
update(); // Store expression
return entry->val_decimal(&null_value, val);
}
@ -3878,6 +3886,16 @@ void Item_func_set_user_var::print_as_stmt(String *str)
str->append(')');
}
bool Item_func_set_user_var::send(Protocol *protocol, String *str_arg)
{
if (result_field)
{
check(1);
update();
return protocol->store(result_field);
}
return Item::send(protocol, str_arg);
}
String *
Item_func_get_user_var::val_str(String *str)
@ -4143,7 +4161,7 @@ bool Item_func_get_user_var::set_value(THD *thd,
Item_func_set_user_var is not fixed after construction, call
fix_fields().
*/
return (!suv || suv->fix_fields(thd, it) || suv->check() || suv->update());
return (!suv || suv->fix_fields(thd, it) || suv->check(0) || suv->update());
}

6
sql/item_func.h
View File

@ -54,7 +54,7 @@ public:
SP_POINTN,SP_GEOMETRYN,SP_INTERIORRINGN,
NOT_FUNC, NOT_ALL_FUNC,
NOW_FUNC, TRIG_COND_FUNC,
GUSERVAR_FUNC, COLLATE_FUNC,
SUSERVAR_FUNC, GUSERVAR_FUNC, COLLATE_FUNC,
EXTRACT_FUNC, CHAR_TYPECAST_FUNC, FUNC_SP, UDF_FUNC };
enum optimize_type { OPTIMIZE_NONE,OPTIMIZE_KEY,OPTIMIZE_OP, OPTIMIZE_NULL,
OPTIMIZE_EQUAL };
@ -1167,13 +1167,15 @@ public:
Item_func_set_user_var(LEX_STRING a,Item *b)
:Item_func(b), cached_result_type(INT_RESULT), name(a)
{}
enum Functype functype() const { return SUSERVAR_FUNC; }
double val_real();
longlong val_int();
String *val_str(String *str);
my_decimal *val_decimal(my_decimal *);
bool update_hash(void *ptr, uint length, enum Item_result type,
CHARSET_INFO *cs, Derivation dv, bool unsigned_arg= 0);
bool check();
bool send(Protocol *protocol, String *str_arg);
bool check(bool use_result_field);
bool update();
enum Item_result result_type () const { return cached_result_type; }
bool fix_fields(THD *thd, Item **ref);

2
sql/set_var.cc
View File

@ -3252,7 +3252,7 @@ int set_var_user::check(THD *thd)
0 can be passed as last argument (reference on item)
*/
return (user_var_item->fix_fields(thd, (Item**) 0) ||
user_var_item->check()) ? -1 : 0;
user_var_item->check(0)) ? -1 : 0;
}

2
sql/sql_class.cc
View File

@ -1883,7 +1883,7 @@ bool select_dumpvar::send_data(List<Item> &items)
{
if ((xx=li++))
{
xx->check();
xx->check(0);
xx->update();
}
}

4
sql/sql_select.cc
View File

@ -13365,7 +13365,9 @@ change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
{
Field *field;
if (item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM)
if ((item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM) ||
(item->type() == Item::FUNC_ITEM &&
((Item_func*)item)->functype() == Item_func::SUSERVAR_FUNC))
item_field= item;
else
{