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MDEV-22852: SIGSEGV in sortlength (optimized builds)

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The issue here is for a DEPENDENT subquery that has an aggregate function in the ORDER BY clause,
is wrapped inside an Item_aggregate_ref. For computation of ORDER BY we need to refer to the
temp table field corresponding to this item. But in the function make_sortorder, we were
explicitly casting Item_aggrgate_ref to Item_sum, which leads to us not getting the temp
table field corresponding to the item.
This commit is contained in:
Varun Gupta 2020-07-01 11:39:22 +05:30
parent 4a2e7b5368
commit fbfb5b5f68
3 changed files with 32 additions and 1 deletions
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12
mysql-test/r/subselect4.result
View File

@ -2566,3 +2566,15 @@ SELECT sum(a), t2.a, t2.b FROM t2 HAVING t2.a IN (SELECT t2.b FROM t1);
sum(a) a b
6 1 1
DROP TABLE t1,t2;
#
# MDEV-22852: SIGSEGV in sortlength (optimized builds)
#
SET @save_optimizer_switch=@@optimizer_switch;
SET optimizer_switch='subquery_cache=off';
CREATE TABLE t1 (a INT,b INT);
INSERT INTO t1 VALUES (0,0),(0,0);
SELECT (SELECT DISTINCT t1i.b FROM t1 t1i GROUP BY t1i.a ORDER BY MAX(t1o.b)) FROM t1 AS t1o;
(SELECT DISTINCT t1i.b FROM t1 t1i GROUP BY t1i.a ORDER BY MAX(t1o.b))
0
SET @@optimizer_switch= @save_optimizer_switch;
DROP TABLE t1;

12
mysql-test/t/subselect4.test
View File

@ -2101,3 +2101,15 @@ SET @@sql_select_limit= @save_sql_select_limit;
eval EXPLAIN EXTENDED $query;
eval $query;
DROP TABLE t1,t2;
--echo #
--echo # MDEV-22852: SIGSEGV in sortlength (optimized builds)
--echo #
SET @save_optimizer_switch=@@optimizer_switch;
SET optimizer_switch='subquery_cache=off';
CREATE TABLE t1 (a INT,b INT);
INSERT INTO t1 VALUES (0,0),(0,0);
SELECT (SELECT DISTINCT t1i.b FROM t1 t1i GROUP BY t1i.a ORDER BY MAX(t1o.b)) FROM t1 AS t1o;
SET @@optimizer_switch= @save_optimizer_switch;
DROP TABLE t1;

9
sql/filesort.cc
View File

@ -483,7 +483,14 @@ uint Filesort::make_sortorder(THD *thd, JOIN *join, table_map first_table_bit)
if (item->type() == Item::FIELD_ITEM)
pos->field= ((Item_field*) item)->field;
else if (item->type() == Item::SUM_FUNC_ITEM && !item->const_item())
pos->field= ((Item_sum*) item)->get_tmp_table_field();
{
// Aggregate, or Item_aggregate_ref
DBUG_ASSERT(first->type() == Item::SUM_FUNC_ITEM ||
(first->type() == Item::REF_ITEM &&
static_cast<Item_ref*>(first)->ref_type() ==
Item_ref::AGGREGATE_REF));
pos->field= first->get_tmp_table_field();
}
else if (item->type() == Item::COPY_STR_ITEM)
{ // Blob patch
pos->item= ((Item_copy*) item)->get_item();