diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 82e54c084b8..be423e2c262 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3802,7 +3802,8 @@ static struct config_enum ConfigureNamesEnum[] =
 		{"trace_recovery_messages", PGC_SIGHUP, DEVELOPER_OPTIONS,
 			gettext_noop("Enables logging of recovery-related debugging information."),
 			gettext_noop("Each level includes all the levels that follow it. The later"
-						 " the level, the fewer messages are sent.")
+						 " the level, the fewer messages are sent."),
+			GUC_NOT_IN_SAMPLE
 		},
 		&trace_recovery_messages,
 
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2b1ebb797ec..c3894b67ef7 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -287,6 +287,7 @@
 # - Planner Method Configuration -
 
 #enable_bitmapscan = on
+#enable_gathermerge = on
 #enable_hashagg = on
 #enable_hashjoin = on
 #enable_indexscan = on