MDEV-31162 Crash for query using ROWNUM over multi-table view with ORDER BYbb-10.6-igor

This bug could cause a crash of the server when processing a query with
ROWNUM() if it used in its FROM list a reference to a mergeable view
defined as SELECT over more than one table that contained ORDER BY clause.
When a mergeable view with ORDER BY clause and without LIMIT clause is used
in the FROM list of a query that does not have ORDER BY clause the ORDER BY
clause of the view is moved to the query. The code that performed this
transformation forgot to delete the moved ORDER BY list from the view.
If a query contains ROWNUM() and uses a mergeable multi-table view with
ORDER BY then according to the current code of TABLE_LIST::init_derived()
the view has to be forcibly materialized. As the query and the view shared
the same items in its ORDER BY lists they could not be properly resolved
either in the query or in the view. This led to a crash of the server.

This patch has returned back the original signature of LEX::can_not_use_merged()
to comply with 10.4 code of the condition that checks whether a megeable
view has to be forcibly materialized.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index 2076fdf21f4..d457e309014 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -3659,7 +3659,7 @@ public:
 
   bool can_be_merged();
   bool can_use_merged();
-  bool can_not_use_merged(bool no_update_or_delete);
+  bool can_not_use_merged();
   bool only_view_structure();
   bool need_correct_ident();
   uint8 get_effective_with_check(TABLE_LIST *view);