report_null_as_sync_priority.patch

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index d42a461..fe511b5 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1749,7 +1749,7 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
      <entry><type>integer</></entry>
      <entry>Priority of this standby server for being chosen as the
       synchronous standby in a priority-based synchronous replication.
-      This has no effect in a quorum-based synchronous replication.</entry>
+      This value is NULL if in a quorum-based synchronous replication.</entry>
     </row>
     <row>
      <entry><structfield>sync_state</></entry>
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index dbb10c7..b57244b 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -3127,7 +3127,15 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
 			else
 				values[8] = IntervalPGetDatum(offset_to_interval(applyLag));
 
-			values[9] = Int32GetDatum(priority);
+			/*
+			 * The priority appers NULL as it is not used in quorum-based
+			 * sync replication.
+			 */
+			if (SyncRepConfig &&
+				SyncRepConfig->syncrep_method == SYNC_REP_QUORUM)
+				nulls[9] = true;
+			else
+				values[9] = Int32GetDatum(priority);
 
 			/*
 			 * More easily understood version of standby state. This is purely
diff --git a/src/test/recovery/t/007_sync_rep.pl b/src/test/recovery/t/007_sync_rep.pl
index e11b428..f29b4db 100644
--- a/src/test/recovery/t/007_sync_rep.pl
+++ b/src/test/recovery/t/007_sync_rep.pl
@@ -185,9 +185,9 @@ standby4|0|async),
 # Check that all the listed standbys are considered as candidates
 # for sync standbys in a quorum-based sync replication.
 test_sync_state(
-$node_master, qq(standby1|1|quorum
-standby2|2|quorum
-standby4|0|async),
+$node_master, qq(standby1||quorum
+standby2||quorum
+standby4||async),
 '2 quorum and 1 async',
 'ANY 2(standby1, standby2)');
 
@@ -197,9 +197,9 @@ $node_standby_3->start;
 # Check that the setting of 'ANY 2(*)' chooses all standbys as
 # candidates for quorum sync standbys.
 test_sync_state(
-$node_master, qq(standby1|1|quorum
-standby2|1|quorum
-standby3|1|quorum
-standby4|1|quorum),
+$node_master, qq(standby1||quorum
+standby2||quorum
+standby3||quorum
+standby4||quorum),
 'all standbys are considered as candidates for quorum sync standbys',
 'ANY 2(*)');