Fix accumulation of old rows in mysql.gtid_slave_pos

This would happen especially in optimistic parallel replication, where there
is a good chance that a transaction will be rolled back (due to conflicts)
after it has executed record_gtid(). If the transaction did any deletions of
old rows as part of record_gtid(), those deletions will be undone as well.
And the code did not properly ensure that the deletions would be re-tried.

This patch makes record_gtid() remember the list of deletions done as part
of a transaction. Then in rpl_slave_state::update() when the changes have
been committed, we discard the list. However, in case of error and rollback,
in cleanup_context() we will instead put the list back into
rpl_global_gtid_slave_state so that the deletions will be re-tried later.

Probably fixes part of the cause of MDEV-12147 as well.

Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/sql/rpl_rli.h b/sql/rpl_rli.h
index 74d5b6fe416..b40a34a54e6 100644
--- a/sql/rpl_rli.h
+++ b/sql/rpl_rli.h
@@ -676,6 +676,11 @@ struct rpl_group_info
   /* Needs room for "Gtid D-S-N\x00". */
   char gtid_info_buf[5+10+1+10+1+20+1];
 
+  /* List of not yet committed deletions in mysql.gtid_slave_pos. */
+  rpl_slave_state::list_element *pending_gtid_delete_list;
+  /* Domain associated with pending_gtid_delete_list. */
+  uint32 pending_gtid_delete_list_domain;
+
   /*
     The timestamp, from the master, of the commit event.
     Used to do delayed update of rli->last_master_timestamp, for getting
@@ -817,6 +822,12 @@ struct rpl_group_info
   char *gtid_info();
   void unmark_start_commit();
 
+  static void pending_gtid_deletes_free(rpl_slave_state::list_element *list);
+  void pending_gtid_deletes_save(uint32 domain_id,
+                                 rpl_slave_state::list_element *list);
+  void pending_gtid_deletes_put_back();
+  void pending_gtid_deletes_clear();
+
   time_t get_row_stmt_start_timestamp()
   {
     return row_stmt_start_timestamp;