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MDEV-10097: Assertion `count > 0' failed in Item_sum_sum::add_helper(bool)

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When specifying a RANGE type frame that exceeds the partition size, both
for the top and bottom cursors we end up removing more rows than added
to the aggregate function. This happens because our TOP range cursor,
which removes values from the aggregate function, would be allowed to breach
partition boundaries, while the BOTTOM range cursor would not.

To prevent this from happening, force the TOP range cursor to only move
within the current partition, as does the BOTTOM range cursor.
This commit is contained in:
Vicențiu Ciorbaru
2016-09-04 05:51:10 +03:00
parent 23e8b508a0
commit 1adc3fab23
3 changed files with 55 additions and 4 deletions
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21
sql/sql_window.cc
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@ -877,7 +877,7 @@ private:
class Frame_range_n_top : public Frame_cursor
{
Table_read_cursor cursor;
Partition_read_cursor cursor;
Cached_item_item *range_expr;
@ -885,6 +885,9 @@ class Frame_range_n_top : public Frame_cursor
Item *item_add;
const bool is_preceding;
bool end_of_partition;
/*
1 when order_list uses ASC ordering
-1 when order_list uses DESC ordering
@ -895,7 +898,8 @@ public:
SQL_I_List<ORDER> *partition_list,
SQL_I_List<ORDER> *order_list,
bool is_preceding_arg, Item *n_val_arg) :
n_val(n_val_arg), item_add(NULL), is_preceding(is_preceding_arg)
cursor(thd, partition_list), n_val(n_val_arg), item_add(NULL),
is_preceding(is_preceding_arg)
{
DBUG_ASSERT(order_list->elements == 1);
Item *src_expr= order_list->first->item[0];
@ -921,13 +925,15 @@ public:
void init(READ_RECORD *info)
{
cursor.init(info);
}
void pre_next_partition(ha_rows rownum)
{
// Save the value of FUNC(current_row)
range_expr->fetch_value_from(item_add);
cursor.on_next_partition(rownum);
end_of_partition= false;
}
void next_partition(ha_rows rownum)
@ -938,11 +944,15 @@ public:
void pre_next_row()
{
if (end_of_partition)
return;
range_expr->fetch_value_from(item_add);
}
void next_row()
{
if (end_of_partition)
return;
/*
Ok, our cursor is at the first row R where
(prev_row + n) >= R
@ -960,12 +970,15 @@ public:
private:
void walk_till_non_peer()
{
while (!cursor.get_next())
int res;
while (!(res= cursor.get_next()))
{
if (order_direction * range_expr->cmp_read_only() <= 0)
break;
remove_value_from_items();
}
if (res)
end_of_partition= true;
}
};