MDEV-4937: sql_slave_skip_counter does not work with GTID

The sql_slave_skip_counter is important to be able to recover replication from
certain errors. Often, an appropriate solution is to set
sql_slave_skip_counter to skip over a problem event. But setting
sql_slave_skip_counter produced an error in GTID mode, with a suggestion to
instead set @@gtid_slave_pos to point past the problem event. This however is
not always possible; for example, in case of an INCIDENT event, that event
does not have any GTID to assign to @@gtid_slave_pos.

With this patch, sql_slave_skip_counter now works in GTID mode the same was as
in non-GTID mode. When set, that many initial events are skipped when the SQL
thread starts, plus as many extra events are needed to completely skip any
partially skipped event group. The GTID position is updated to point past the
skipped event(s).

1 files changed, 21 insertions, 6 deletions

diff --git a/sql/slave.cc b/sql/slave.cc
index f755cb63558..3d6809b575a 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -3521,9 +3521,6 @@ static int exec_relay_log_event(THD* thd, Relay_log_info* rli,
 
       if (opt_gtid_ignore_duplicates)
       {
-        serial_rgi->current_gtid.domain_id= gev->domain_id;
-        serial_rgi->current_gtid.server_id= gev->server_id;
-        serial_rgi->current_gtid.seq_no= gev->seq_no;
         int res= rpl_global_gtid_slave_state.check_duplicate_gtid
           (&serial_rgi->current_gtid, serial_rgi);
         if (res < 0)
@@ -4366,6 +4363,7 @@ pthread_handler_t handle_slave_sql(void *arg)
   char saved_master_log_name[FN_REFLEN];
   my_off_t UNINIT_VAR(saved_log_pos);
   my_off_t UNINIT_VAR(saved_master_log_pos);
+  String saved_skip_gtid_pos;
   my_off_t saved_skip= 0;
   Master_info *mi= ((Master_info*)arg);
   Relay_log_info* rli = &mi->rli;
@@ -4571,6 +4569,12 @@ log '%s' at position %s, relay log '%s' position: %s%s", RPL_LOG_NAME,
     strmake_buf(saved_master_log_name, rli->group_master_log_name);
     saved_log_pos= rli->group_relay_log_pos;
     saved_master_log_pos= rli->group_master_log_pos;
+    if (mi->using_gtid != Master_info::USE_GTID_NO)
+    {
+      saved_skip_gtid_pos.append(STRING_WITH_LEN(", GTID '"));
+      rpl_append_gtid_state(&saved_skip_gtid_pos, false);
+      saved_skip_gtid_pos.append(STRING_WITH_LEN("'; "));
+    }
     saved_skip= rli->slave_skip_counter;
   }
   if ((rli->until_condition == Relay_log_info::UNTIL_MASTER_POS ||
@@ -4594,16 +4598,27 @@ log '%s' at position %s, relay log '%s' position: %s%s", RPL_LOG_NAME,
 
     if (saved_skip && rli->slave_skip_counter == 0)
     {
+      String tmp;
+      if (mi->using_gtid != Master_info::USE_GTID_NO)
+      {
+        tmp.append(STRING_WITH_LEN(", GTID '"));
+        rpl_append_gtid_state(&tmp, false);
+        tmp.append(STRING_WITH_LEN("'; "));
+      }
+
       sql_print_information("'SQL_SLAVE_SKIP_COUNTER=%ld' executed at "
         "relay_log_file='%s', relay_log_pos='%ld', master_log_name='%s', "
-        "master_log_pos='%ld' and new position at "
+        "master_log_pos='%ld'%s and new position at "
         "relay_log_file='%s', relay_log_pos='%ld', master_log_name='%s', "
-        "master_log_pos='%ld' ",
+        "master_log_pos='%ld'%s ",
         (ulong) saved_skip, saved_log_name, (ulong) saved_log_pos,
         saved_master_log_name, (ulong) saved_master_log_pos,
+        saved_skip_gtid_pos.c_ptr_safe(),
         rli->group_relay_log_name, (ulong) rli->group_relay_log_pos,
-        rli->group_master_log_name, (ulong) rli->group_master_log_pos);
+        rli->group_master_log_name, (ulong) rli->group_master_log_pos,
+        tmp.c_ptr_safe());
       saved_skip= 0;
+      saved_skip_gtid_pos.free();
     }
     
     if (exec_relay_log_event(thd, rli, serial_rgi))