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Bug#28261: Wrong DATETIME comparison result when the GET_USER_VAR function

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is involved.

The Arg_comparator::compare_datetime() comparator caches its arguments if
they are constants i.e. const_item() returns true. The
Item_func_get_user_var::const_item() returns true or false based on
the current query_id and the query_id where the variable was created.
Thus even if a query can change its value its const_item() still will return
true. All this leads to a wrong comparison result when an object of the
Item_func_get_user_var class is involved.

Now the Arg_comparator::can_compare_as_dates() and the
get_datetime_value() functions never cache result of the GET_USER_VAR()
function (the Item_func_get_user_var class).


mysql-test/t/type_datetime.test:
  A test case is added for the bug#28261: Wrong DATETIME comparison result when the GET_USER_VAR function
  is involved.
mysql-test/r/type_datetime.result:
  A test case is added for the bug#28261: Wrong DATETIME comparison result when the GET_USER_VAR function
  is involved.
sql/item_cmpfunc.cc:
  Bug#28261: Wrong DATETIME comparison result when the GET_USER_VAR function
  is involved.
  Now the Arg_comparator::can_compare_as_dates() and the
  get_datetime_value() functions never cache result of the GET_USER_VAR()
  function (the Item_func_get_user_var class).
This commit is contained in:
unknown 2007-05-17 23:09:45 +04:00
parent 418a2983c0
commit c4a4df5aa4
3 changed files with 49 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
mysql-test/r/type_datetime.result
View File

@ -352,3 +352,27 @@ select left(f1,10) = curdate() from t1;
left(f1,10) = curdate()
1
drop table t1;
create table t1(f1 date);
insert into t1 values('01-01-01'),('02-02-02'),('01-01-01'),('02-02-02');
set @bug28261='';
select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
if(@bug28261 = f1, '', @bug28261:= f1)
2001-01-01
2002-02-02
2001-01-01
2002-02-02
Warnings:
Warning 1292 Incorrect date value: '' for column 'f1' at row 1
select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
if(@bug28261 = f1, '', @bug28261:= f1)
2001-01-01
2002-02-02
2001-01-01
2002-02-02
select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
if(@bug28261 = f1, '', @bug28261:= f1)
2001-01-01
2002-02-02
2001-01-01
2002-02-02
drop table t1;

12
mysql-test/t/type_datetime.test
View File

@ -234,3 +234,15 @@ create table t1 (f1 date);
insert into t1 values (curdate());
select left(f1,10) = curdate() from t1;
drop table t1;
#
# Bug#28261: Wrong DATETIME comparison result when the GET_USER_VAR function
# is involved.
#
create table t1(f1 date);
insert into t1 values('01-01-01'),('02-02-02'),('01-01-01'),('02-02-02');
set @bug28261='';
select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
select if(@bug28261 = f1, '', @bug28261:= f1) from t1;
drop table t1;

15
sql/item_cmpfunc.cc
View File

@ -633,7 +633,13 @@ Arg_comparator::can_compare_as_dates(Item *a, Item *b, ulonglong *const_value)
if (cmp_type != CMP_DATE_DFLT)
{
if (cmp_type != CMP_DATE_WITH_DATE && str_arg->const_item())
/*
Do not cache GET_USER_VAR() function as its const_item() may return TRUE
for the current thread but it still may change during the execution.
*/
if (cmp_type != CMP_DATE_WITH_DATE && str_arg->const_item() &&
(str_arg->type() != Item::FUNC_ITEM ||
((Item_func*)str_arg)->functype() != Item_func::GUSERVAR_FUNC))
{
THD *thd= current_thd;
ulonglong value;
@ -780,7 +786,12 @@ get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
MYSQL_TYPE_DATE ? MYSQL_TIMESTAMP_DATE : MYSQL_TIMESTAMP_DATETIME;
value= get_date_from_str(thd, str, t_type, warn_item->name, &error);
}
if (item->const_item() && cache_arg)
/*
Do not cache GET_USER_VAR() function as its const_item() may return TRUE
for the current thread but it still may change during the execution.
*/
if (item->const_item() && cache_arg && (item->type() != Item::FUNC_ITEM ||
((Item_func*)item)->functype() != Item_func::GUSERVAR_FUNC))
{
Item_cache_int *cache= new Item_cache_int();
/* Mark the cache as non-const to prevent re-caching. */