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MDEV-13774: Server Crash on Execute of SQL Statement

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Window functions can not be used as arguments to aggregate functions, as
the aggregation happens before window function computation. Disallow
such constructs by returning an error.

In order to detect this case a change was needed in the base
Item_sum_xxx::fix_fields to propagate the with_window_func flag.

Item_func_group_concat requires the same change.
This commit is contained in:
Vicențiu Ciorbaru 2017-09-11 22:46:11 +03:00
commit 454b9b1bdc
4 changed files with 277 additions and 2 deletions
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23
sql/item_sum.cc
View file

@ -100,7 +100,11 @@ bool Item_sum::init_sum_func_check(THD *thd)
The method verifies whether context conditions imposed on a usage
of any set function are met for this occurrence.
It checks whether the set function occurs in the position where it
The function first checks if we are using any window functions as
arguments to the set function. In that case it returns an error.
Afterwards, it checks whether the set function occurs in the position where it
can be aggregated and, when it happens to occur in argument of another
set function, the method checks that these two functions are aggregated in
different subqueries.
@ -151,6 +155,20 @@ bool Item_sum::check_sum_func(THD *thd, Item **ref)
curr_sel->name_visibility_map);
bool invalid= FALSE;
DBUG_ASSERT(curr_sel->name_visibility_map); // should be set already
/*
Window functions can not be used as arguments to sum functions.
Aggregation happes before window function computation, so there
are no values to aggregate over.
*/
if (with_window_func)
{
my_message(ER_SUM_FUNC_WITH_WINDOW_FUNC_AS_ARG,
ER_THD(thd, ER_SUM_FUNC_WITH_WINDOW_FUNC_AS_ARG),
MYF(0));
return TRUE;
}
if (window_func_sum_expr_flag)
return false;
/*
@ -1108,6 +1126,7 @@ Item_sum_num::fix_fields(THD *thd, Item **ref)
return TRUE;
set_if_bigger(decimals, args[i]->decimals);
with_subselect|= args[i]->with_subselect;
with_window_func|= args[i]->with_window_func;
}
result_field=0;
max_length=float_length(decimals);
@ -1139,6 +1158,7 @@ Item_sum_hybrid::fix_fields(THD *thd, Item **ref)
return TRUE;
Type_std_attributes::set(args[0]);
with_subselect= args[0]->with_subselect;
with_window_func|= args[0]->with_window_func;
Item *item2= item->real_item();
if (item2->type() == Item::FIELD_ITEM)
@ -3480,6 +3500,7 @@ Item_func_group_concat::fix_fields(THD *thd, Item **ref)
args[i]->check_cols(1))
return TRUE;
with_subselect|= args[i]->with_subselect;
with_window_func|= args[i]->with_window_func;
}
/* skip charset aggregation for order columns */