PXC-4799 : PXC member used for backups fails with Inconsistency when …

mysql-test/r/pxc4799.result

@@ -0,0 +1,22 @@
+#
+#  PXC-4799 : "PXC member used for backups fails with Inconsistency
+#             when pending DDL clashes with FTRWL" - single node test.
+#
+connect  con1, localhost, root,,;
+connection default;
+LOCK INSTANCE FOR BACKUP;
+connection con1;
+CREATE TABLE t1 (a INT);
+connection default;
+FLUSH TABLES WITH READ LOCK;
+UNLOCK TABLES;
+UNLOCK INSTANCE;
+connection con1;
+# Reap result of CREATE TABLE t1
+#
+# Without the patch the CREAT TABLE statement would failed with
+# ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction
+# Clean up.
+DROP TABLE t1;
+disconnect con1;
+connection default;

mysql-test/t/pxc4799.test

@@ -0,0 +1,43 @@
+--echo #
+--echo #  PXC-4799 : "PXC member used for backups fails with Inconsistency
+--echo #             when pending DDL clashes with FTRWL" - single node test.
+--echo #
+
+
+--enable_connect_log
+
+--connect (con1, localhost, root,,)
+let $con1_id= `SELECT CONNECTION_ID()`;
+
+--connection default
+LOCK INSTANCE FOR BACKUP;
+
+--connection con1
+--send CREATE TABLE t1 (a INT)
+
+--connection default
+let $wait_condition=
+  SELECT count(*) = 1 FROM INFORMATION_SCHEMA.PROCESSLIST
+  WHERE state = "Waiting for backup lock" AND id = $con1_id;
+--source include/wait_condition.inc
+
+FLUSH TABLES WITH READ LOCK;
+
+UNLOCK TABLES;
+UNLOCK INSTANCE;
+
+--connection con1
+--echo # Reap result of CREATE TABLE t1
+--echo #
+--echo # Without the patch the CREAT TABLE statement would failed with
+--echo # ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction
+--reap
+
+--echo # Clean up.
+DROP TABLE t1;
+--disconnect con1
+--source include/wait_until_disconnected.inc
+
+--connection default
+--disable_connect_log
+

sql/mdl.cc

@@ -120,8 +120,8 @@ static void init_mdl_psi_keys() {
 */
 
 PSI_stage_info MDL_key::m_namespace_to_wait_state_name[NAMESPACE_END] = {
-    {0, "Waiting for global read lock", 0, PSI_DOCUMENT_ME},
     {0, "Waiting for backup lock", 0, PSI_DOCUMENT_ME},
+    {0, "Waiting for global read lock", 0, PSI_DOCUMENT_ME},
     {0, "Waiting for tablespace metadata lock", 0, PSI_DOCUMENT_ME},
     {0, "Waiting for schema metadata lock", 0, PSI_DOCUMENT_ME},
     {0, "Waiting for table metadata lock", 0, PSI_DOCUMENT_ME},

sql/mdl.h

@@ -376,10 +376,10 @@ struct MDL_key {
     update m_namespace_to_wait_state_name array in mdl.cc!
 
     Different types of objects exist in different namespaces
-     - GLOBAL is used for the global read lock.
      - BACKUP_LOCK is to block any operations that could cause
        inconsistent backup. Such operations are most DDL statements,
        and some administrative statements.
+     - GLOBAL is used for the global read lock.
      - TABLESPACE is for tablespaces.
      - SCHEMA is for schemas (aka databases).
      - TABLE is for tables and views.
@@ -401,8 +401,8 @@ struct MDL_key {
     treatment - waiting is aborted if connection to client is lost.
   */
   enum enum_mdl_namespace {
-    GLOBAL = 0,
-    BACKUP_LOCK, /* Oracle LOCK INSTANCE FOR BACKUP */
+    BACKUP_LOCK = 0, /* Oracle LOCK INSTANCE FOR BACKUP */
+    GLOBAL,
     TABLESPACE,
     SCHEMA,
     TABLE,