expose confirmed_flush for replication slots

diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e82a53a..ffaf451 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -674,7 +674,8 @@ CREATE VIEW pg_replication_slots AS
             L.active_pid,
             L.xmin,
             L.catalog_xmin,
-            L.restart_lsn
+            L.restart_lsn,
+            L.confirmed_flush_lsn
     FROM pg_get_replication_slots() AS L
             LEFT JOIN pg_database D ON (L.datoid = D.oid);
 
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9a2793f..ddbf8c4 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -158,7 +158,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
 Datum
 pg_get_replication_slots(PG_FUNCTION_ARGS)
 {
-#define PG_GET_REPLICATION_SLOTS_COLS 9
+#define PG_GET_REPLICATION_SLOTS_COLS 10
 	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
 	TupleDesc	tupdesc;
 	Tuplestorestate *tupstore;
@@ -206,6 +206,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
 		TransactionId xmin;
 		TransactionId catalog_xmin;
 		XLogRecPtr	restart_lsn;
+		XLogRecPtr	confirmed_flush_lsn;
 		pid_t		active_pid;
 		Oid			database;
 		NameData	slot_name;
@@ -224,6 +225,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
 			catalog_xmin = slot->data.catalog_xmin;
 			database = slot->data.database;
 			restart_lsn = slot->data.restart_lsn;
+			confirmed_flush_lsn = slot->data.confirmed_flush;
 			namecpy(&slot_name, &slot->data.name);
 			namecpy(&plugin, &slot->data.plugin);
 
@@ -273,6 +275,11 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
 		else
 			nulls[i++] = true;
 
+		if (confirmed_flush_lsn != InvalidTransactionId)
+			values[i++] = LSNGetDatum(confirmed_flush_lsn);
+		else
+			nulls[i++] = true;
+
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
 	}
 
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 6fd1278..aee82d2 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -5183,7 +5183,7 @@ DATA(insert OID = 3779 (  pg_create_physical_replication_slot PGNSP PGUID 12 1 0
 DESCR("create a physical replication slot");
 DATA(insert OID = 3780 (  pg_drop_replication_slot PGNSP PGUID 12 1 0 0 0 f f f f f f v 1 0 2278 "19" _null_ _null_ _null_ _null_ _null_ pg_drop_replication_slot _null_ _null_ _null_ ));
 DESCR("drop a replication slot");
-DATA(insert OID = 3781 (  pg_get_replication_slots	PGNSP PGUID 12 1 10 0 0 f f f f f t s 0 0 2249 "" "{19,19,25,26,16,23,28,28,3220}" "{o,o,o,o,o,o,o,o,o}" "{slot_name,plugin,slot_type,datoid,active,active_pid,xmin,catalog_xmin,restart_lsn}" _null_ _null_ pg_get_replication_slots _null_ _null_ _null_ ));
+DATA(insert OID = 3781 (  pg_get_replication_slots	PGNSP PGUID 12 1 10 0 0 f f f f f t s 0 0 2249 "" "{19,19,25,26,16,23,28,28,3220,3220}" "{o,o,o,o,o,o,o,o,o,o}" "{slot_name,plugin,slot_type,datoid,active,active_pid,xmin,catalog_xmin,restart_lsn,confirmed_flush_lsn}" _null_ _null_ pg_get_replication_slots _null_ _null_ _null_ ));
 DESCR("information about replication slots currently in use");
 DATA(insert OID = 3786 (  pg_create_logical_replication_slot PGNSP PGUID 12 1 0 0 0 f f f f f f v 2 0 2249 "19 19" "{19,19,25,3220}" "{i,i,o,o}" "{slot_name,plugin,slot_name,xlog_position}" _null_ _null_ pg_create_logical_replication_slot _null_ _null_ _null_ ));
 DESCR("set up a logical replication slot");
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index cd53375..63cd323 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1416,8 +1416,9 @@ pg_replication_slots| SELECT l.slot_name,
     l.active_pid,
     l.xmin,
     l.catalog_xmin,
-    l.restart_lsn
-   FROM (pg_get_replication_slots() l(slot_name, plugin, slot_type, datoid, active, active_pid, xmin, catalog_xmin, restart_lsn)
+    l.restart_lsn,
+    l.confirmed_flush_lsn
+   FROM (pg_get_replication_slots() l(slot_name, plugin, slot_type, datoid, active, active_pid, xmin, catalog_xmin, restart_lsn, confirmed_flush_lsn)
      LEFT JOIN pg_database d ON ((l.datoid = d.oid)));
 pg_roles| SELECT pg_authid.rolname,
     pg_authid.rolsuper,