Bug #44290: explain crashes for subquery with distinct in

            SQL_SELECT::test_quick_select

The crash was caused by an incomplete cleanup of JOIN_TAB::select
during the filesort of rows for GROUP BY clause inside a subquery.
Queries where a quick index access is replaced with filesort was
was affected. For example:

  SELECT 1 FROM
    (SELECT COUNT(DISTINCT c1) FROM t1
       WHERE c2 IN (1, 1) AND c3 = 2 GROUP BY c2) x

Quick index access related data in the SQL_SELECT::test_quick_select
function was inconsistent after an incomplete cleanup.
This function has been completed to prevent crashes in the
SQL_SELECT::test_quick_select function.


mysql-test/include/mix1.inc:
  Add test case for bug #44290.
mysql-test/r/innodb_mysql.result:
  Add test case for bug #44290.
sql/sql_select.cc:
  Bug #44290: explain crashes for subquery with distinct in
              SQL_SELECT::test_quick_select
  
  Quick index access related data in the SQL_SELECT::test_quick_select
  function was inconsistent after an incomplete cleanup.
  This function has been completed to prevent crashes in the
  SQL_SELECT::test_quick_select function.

1 files changed, 1 insertions, 0 deletions

diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index cdae1581a0c..ab9c060c69c 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -13481,6 +13481,7 @@ create_sort_index(THD *thd, JOIN *join, ORDER *order,
   {
     select->cleanup();				// filesort did select
     tab->select= 0;
+    table->quick_keys.clear_all();  // as far as we cleanup select->quick
   }
   tab->select_cond=0;
   tab->last_inner= 0;