MDEV-5189: Incorrect parallel apply in parallel replication

Two problems were fixed:

1. When not in GTID mode (master_use_gtid=no), then we must not apply events
   in different domains in parallel (in non-GTID mode we are not capable of
   restarting at different points in different domains).

2. When transactions B and C group commit together, but after and separate
   from A, we can apply B and C in parallel, but both B and C must not start
   until A has committed. Fix sub_id to be globally increasing (not just
   per-domain increasing) so that this wait (which is based on sub_id) can be
   done correctly.

1 files changed, 1 insertions, 3 deletions

diff --git a/sql/rpl_gtid.h b/sql/rpl_gtid.h
index 525b34cb160..39c9aee0b9d 100644
--- a/sql/rpl_gtid.h
+++ b/sql/rpl_gtid.h
@@ -60,7 +60,6 @@ struct rpl_slave_state
   struct element
   {
     struct list_element *list;
-    uint64 last_sub_id;
     uint32 domain_id;
 
     list_element *grab_list() { list_element *l= list; list= NULL; return l; }
@@ -68,8 +67,6 @@ struct rpl_slave_state
     {
       l->next= list;
       list= l;
-      if (last_sub_id < l->sub_id)
-        last_sub_id= l->sub_id;
     }
   };
 
@@ -78,6 +75,7 @@ struct rpl_slave_state
   /* Mutex protecting access to the state. */
   mysql_mutex_t LOCK_slave_state;
 
+  uint64 last_sub_id;
   bool inited;
   bool loaded;