MDEV-6139: UPDATE w/ join against MRG_MyISAM table with read-only sub-table failsUPDATE w/ join against MRG_MyISAM table with read-only sub-table fails

The problem was that on opening all tables TL_WRITE, than local tables which is not updated set to TL_READ, but underlying tables of MyISAMmrg left untouched.

Prartition engine has not this problem.

All cases where lock_type assigned is not changed because call of virtual function is not cheap.

mysql-test/r/multi_update.result

@@ -794,4 +794,23 @@ SELECT * FROM t2;
 col_int_key	pk_1	pk_2	col_int
 1	7	11	4
 DROP TABLE t1,t2;
+#
+# MDEV-6139: UPDATE w/ join against MRG_MyISAM table with read-only
+# sub-table fails
+#
+CREATE TABLE t1 (
+id int(10) unsigned,
+a int(11)
+) ENGINE=MyISAM;
+CREATE TABLE t3 (
+id int(10) unsigned,
+b int(11)
+) ENGINE=MyISAM;
+CREATE TABLE t2 (
+id int(10) unsigned,
+b int(11)
+) ENGINE=MRG_MyISAM UNION=(t3);
+FLUSH TABLES;
+update t1 join t2 using (id) set t1.a=t2.b;
+drop table t2, t3, t1;
 end of 5.5 tests

mysql-test/t/multi_update.test

@@ -808,5 +808,37 @@ SELECT * FROM t2;
 
 DROP TABLE t1,t2;
 
+--echo #
+--echo # MDEV-6139: UPDATE w/ join against MRG_MyISAM table with read-only
+--echo # sub-table fails
+--echo #
+
+CREATE TABLE t1 (
+  id int(10) unsigned,
+  a int(11)
+) ENGINE=MyISAM;
+
+CREATE TABLE t3 (
+  id int(10) unsigned,
+  b int(11)
+) ENGINE=MyISAM;
+
+CREATE TABLE t2 (
+  id int(10) unsigned,
+  b int(11)
+) ENGINE=MRG_MyISAM UNION=(t3);
+
+FLUSH TABLES;
+
+let $MYSQLD_DATADIR= `select @@datadir`;
+--disable_result_log
+--exec $MYISAMPACK -f $MYSQLD_DATADIR/test/t3
+--exec $MYISAMCHK -rq $MYSQLD_DATADIR/test/t3
+--enable_result_log
+
+update t1 join t2 using (id) set t1.a=t2.b;
+
+drop table t2, t3, t1;
+
 --echo end of 5.5 tests
 

sql/handler.cc

@@ -5285,6 +5285,10 @@ void signal_log_not_needed(struct handlerton, char *log_file)
   DBUG_VOID_RETURN;
 }
 
+void handler::ha_set_lock_type(enum thr_lock_type lock)
+{
+  table->reginfo.lock_type= lock;
+}
 
 #ifdef TRANS_LOG_MGM_EXAMPLE_CODE
 /*

sql/handler.h

@@ -2952,6 +2952,8 @@ public:
   inline int ha_write_tmp_row(uchar *buf);
   inline int ha_update_tmp_row(const uchar * old_data, uchar * new_data);
 
+  virtual void ha_set_lock_type(enum thr_lock_type lock);
+
   friend enum icp_result handler_index_cond_check(void* h_arg);
 };
 

sql/sql_update.cc

@@ -1304,7 +1304,7 @@ int mysql_multi_update_prepare(THD *thd)
       tl->updating= 0;
       /* Update TABLE::lock_type accordingly. */
       if (!tl->placeholder() && !using_lock_tables)
-        tl->table->reginfo.lock_type= tl->lock_type;
+        tl->table->file->ha_set_lock_type(tl->lock_type);
     }
   }
   for (tl= table_list; tl; tl= tl->next_local)

storage/myisammrg/ha_myisammrg.cc

@@ -1713,6 +1713,24 @@ my_bool ha_myisammrg::register_query_cache_dependant_tables(THD *thd
   DBUG_RETURN(FALSE);
 }
 
+
+void ha_myisammrg::ha_set_lock_type(enum thr_lock_type lock)
+{
+  handler::ha_set_lock_type(lock);
+  if (children_l != NULL)
+  {
+    for (TABLE_LIST *child_table= children_l;;
+         child_table= child_table->next_global)
+    {
+      child_table->lock_type=
+        child_table->table->reginfo.lock_type= lock;
+
+      if (&child_table->next_global == children_last_l)
+        break;
+    }
+  }
+}
+
 extern int myrg_panic(enum ha_panic_function flag);
 int myisammrg_panic(handlerton *hton, ha_panic_function flag)
 {

storage/myisammrg/ha_myisammrg.h

@@ -155,4 +155,5 @@ public:
                                           Query_cache *cache,
                                           Query_cache_block_table **block,
                                           uint *n);
+  virtual void ha_set_lock_type(enum thr_lock_type lock);
 };