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a simpler fix for

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MySQL Bug #12408412: GROUP_CONCAT + ORDER BY + INPUT/OUTPUT SAME USER VARIABLE = CRASH
and
MySQL Bug#14664077 SEVERE PERFORMANCE DEGRADATION IN SOME CASES WHEN USER VARIABLES ARE USED


sql/item_func.cc:
  don't use anything from Item_func_set_user_var::fix_fields()
  in Item_func_set_user_var::save_item_result()
sql/sql_class.cc:
  Call suv->save_item_result(item) *before* doing suv->fix_fields(), because
  the former evaluates the item (and caches its value), while the latter marks
  the user variable as non-const. The problem is that the item was fix_field'ed
  when the user variable was const, and it doesn't expect it to change to non-const
  in the middle of the execution.
This commit is contained in:
Sergei Golubchik 2013-02-28 11:46:35 +01:00
parent 6a2d730a7f
commit 027e34e13b
4 changed files with 12 additions and 2 deletions
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2
mysql-test/r/user_var.result
View File

@ -456,4 +456,6 @@ SELECT (@v:=a) <> (@v:=1) FROM t1;
(@v:=a) <> (@v:=1) (@v:=a) <> (@v:=1)
1 1
DROP TABLE t1; DROP TABLE t1;
SET @bug12408412=1;
SELECT GROUP_CONCAT(@bug12408412 ORDER BY 1) INTO @bug12408412;
End of 5.1 tests End of 5.1 tests

8
mysql-test/t/user_var.test
View File

@ -365,4 +365,12 @@ SELECT (@v:=a) <> (@v:=1) FROM t1;
DROP TABLE t1; DROP TABLE t1;
#
# Bug #12408412: GROUP_CONCAT + ORDER BY + INPUT/OUTPUT
# SAME USER VARIABLE = CRASH
#
SET @bug12408412=1;
SELECT GROUP_CONCAT(@bug12408412 ORDER BY 1) INTO @bug12408412;
--echo End of 5.1 tests --echo End of 5.1 tests

2
sql/item_func.cc
View File

@ -4175,7 +4175,7 @@ void Item_func_set_user_var::save_item_result(Item *item)
{ {
DBUG_ENTER("Item_func_set_user_var::save_item_result"); DBUG_ENTER("Item_func_set_user_var::save_item_result");
switch (cached_result_type) { switch (args[0]->result_type()) {
case REAL_RESULT: case REAL_RESULT:
save_result.vreal= item->val_result(); save_result.vreal= item->val_result();
break; break;

2
sql/sql_class.cc
View File

@ -2922,9 +2922,9 @@ int select_dumpvar::send_data(List<Item> &items)
else else
{ {
Item_func_set_user_var *suv= new Item_func_set_user_var(mv->s, item); Item_func_set_user_var *suv= new Item_func_set_user_var(mv->s, item);
suv->save_item_result(item);
if (suv->fix_fields(thd, 0)) if (suv->fix_fields(thd, 0))
DBUG_RETURN (1); DBUG_RETURN (1);
suv->save_item_result(item);
if (suv->update()) if (suv->update())
DBUG_RETURN (1); DBUG_RETURN (1);
} }