Hi, Alexey! On Sep 03, Alexey Botchkov wrote:

revision-id: 17540adc625ff4ac0f00aa10796cb6e763838d18 (mariadb-10.1.35-25-g17540ad) parent(s): 34e026f35a7fbeeaec412547ee207c880944ae68 committer: Alexey Botchkov timestamp: 2018-09-03 16:49:46 +0400 message:

MDEV-15890 Strange error message if you try to FLUSH TABLES <view> after LOCK TABLES <view>.

LOCK view WRITE shouldn't block FLUSH view. So we set the view's mdl_request type to it's tables.

diff --git a/sql/sql_view.cc b/sql/sql_view.cc index 6bd6b6a..d7a2a6b 100644 --- a/sql/sql_view.cc +++ b/sql/sql_view.cc @@ -1534,8 +1534,7 @@ bool mysql_make_view(THD *thd, TABLE_SHARE *share, TABLE_LIST *table, for (tbl= view_main_select_tables; tbl; tbl= tbl->next_local) { tbl->lock_type= table->lock_type; - tbl->mdl_request.set_type((tbl->lock_type >= TL_WRITE_ALLOW_WRITE) ? - MDL_SHARED_WRITE : MDL_SHARED_READ); + tbl->mdl_request.set_type(table->mdl_request.type); }

I agree it's looks like a proper fix. But I'm a bit cautious about possible side effects. A more conservative fix would be only change the lock level for TL_NO_READ_WRITE, like tbl->lock_type == TL_NO_READ_WRITE ? TL_NO_READ_WRITE : tbl->lock_type >= TL_WRITE_ALLOW_WRITE ? MDL_SHARED_WRITE : MDL_SHARED_READ (or with an if(), for readability). But I don't see whether it'll make any difference as compared to your fix. Please, run all tests locally, and I mean *all*, big, ps, embedded. And see if you can think of any cases where this change would cause a change in behavior. After that - ok to push! Regards, Sergei Chief Architect MariaDB and security@mariadb.org