Make pg_stat_wal_receiver consistent with the WAL receiver's shmem info

d140f2f has renamed receivedUpto to flushedUpto, and has added
writtenUpto to the WAL receiver's shared memory information, but
pg_stat_wal_receiver was not consistent with that.  This commit renames
received_lsn to flushed_lsn, and adds a new column called written_lsn.

Bump catalog version.

Author: Michael Paquier
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/20200515090817.GA212736@paquier.xyz

Author: michaelpq

doc/src/sgml/monitoring.sgml

@@ -2541,7 +2541,17 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>received_lsn</structfield> <type>pg_lsn</type>
+       <structfield>written_lsn</structfield> <type>pg_lsn</type>
+      </para>
+      <para>
+       Last write-ahead log location already received and written to disk,
+       but not flushed. This should not be used for data integrity checks.
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>flushed_lsn</structfield> <type>pg_lsn</type>
       </para>
       <para>
        Last write-ahead log location already received and flushed to

src/backend/catalog/system_views.sql

@@ -812,7 +812,8 @@ CREATE VIEW pg_stat_wal_receiver AS
             s.status,
             s.receive_start_lsn,
             s.receive_start_tli,
-            s.received_lsn,
+            s.written_lsn,
+            s.flushed_lsn,
             s.received_tli,
             s.last_msg_send_time,
             s.last_msg_receipt_time,

src/backend/replication/walreceiver.c

@@ -1348,7 +1348,8 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)
 	WalRcvState state;
 	XLogRecPtr	receive_start_lsn;
 	TimeLineID	receive_start_tli;
-	XLogRecPtr	received_lsn;
+	XLogRecPtr	written_lsn;
+	XLogRecPtr	flushed_lsn;
 	TimeLineID	received_tli;
 	TimestampTz last_send_time;
 	TimestampTz last_receipt_time;
@@ -1366,7 +1367,8 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)
 	state = WalRcv->walRcvState;
 	receive_start_lsn = WalRcv->receiveStart;
 	receive_start_tli = WalRcv->receiveStartTLI;
-	received_lsn = WalRcv->flushedUpto;
+	written_lsn = pg_atomic_read_u64(&WalRcv->writtenUpto);
+	flushed_lsn = WalRcv->flushedUpto;
 	received_tli = WalRcv->receivedTLI;
 	last_send_time = WalRcv->lastMsgSendTime;
 	last_receipt_time = WalRcv->lastMsgReceiptTime;
@@ -1413,43 +1415,47 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)
 		else
 			values[2] = LSNGetDatum(receive_start_lsn);
 		values[3] = Int32GetDatum(receive_start_tli);
-		if (XLogRecPtrIsInvalid(received_lsn))
+		if (XLogRecPtrIsInvalid(written_lsn))
 			nulls[4] = true;
 		else
-			values[4] = LSNGetDatum(received_lsn);
-		values[5] = Int32GetDatum(received_tli);
+			values[4] = LSNGetDatum(written_lsn);
+		if (XLogRecPtrIsInvalid(flushed_lsn))
+			nulls[5] = true;
+		else
+			values[5] = LSNGetDatum(flushed_lsn);
+		values[6] = Int32GetDatum(received_tli);
 		if (last_send_time == 0)
-			nulls[6] = true;
+			nulls[7] = true;
 		else
-			values[6] = TimestampTzGetDatum(last_send_time);
+			values[7] = TimestampTzGetDatum(last_send_time);
 		if (last_receipt_time == 0)
-			nulls[7] = true;
+			nulls[8] = true;
 		else
-			values[7] = TimestampTzGetDatum(last_receipt_time);
+			values[8] = TimestampTzGetDatum(last_receipt_time);
 		if (XLogRecPtrIsInvalid(latest_end_lsn))
-			nulls[8] = true;
+			nulls[9] = true;
 		else
-			values[8] = LSNGetDatum(latest_end_lsn);
+			values[9] = LSNGetDatum(latest_end_lsn);
 		if (latest_end_time == 0)
-			nulls[9] = true;
+			nulls[10] = true;
 		else
-			values[9] = TimestampTzGetDatum(latest_end_time);
+			values[10] = TimestampTzGetDatum(latest_end_time);
 		if (*slotname == '\0')
-			nulls[10] = true;
+			nulls[11] = true;
 		else
-			values[10] = CStringGetTextDatum(slotname);
+			values[11] = CStringGetTextDatum(slotname);
 		if (*sender_host == '\0')
-			nulls[11] = true;
+			nulls[12] = true;
 		else
-			values[11] = CStringGetTextDatum(sender_host);
+			values[12] = CStringGetTextDatum(sender_host);
 		if (sender_port == 0)
-			nulls[12] = true;
+			nulls[13] = true;
 		else
-			values[12] = Int32GetDatum(sender_port);
+			values[13] = Int32GetDatum(sender_port);
 		if (*conninfo == '\0')
-			nulls[13] = true;
+			nulls[14] = true;
 		else
-			values[13] = CStringGetTextDatum(conninfo);
+			values[14] = CStringGetTextDatum(conninfo);
 	}
 
 	/* Returns the record as Datum */

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202005121
+#define CATALOG_VERSION_NO	202005171
 
 #endif

src/include/catalog/pg_proc.dat

@@ -5244,9 +5244,9 @@
 { oid => '3317', descr => 'statistics: information about WAL receiver',
   proname => 'pg_stat_get_wal_receiver', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
-  proallargtypes => '{int4,text,pg_lsn,int4,pg_lsn,int4,timestamptz,timestamptz,pg_lsn,timestamptz,text,text,int4,text}',
-  proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{pid,status,receive_start_lsn,receive_start_tli,received_lsn,received_tli,last_msg_send_time,last_msg_receipt_time,latest_end_lsn,latest_end_time,slot_name,sender_host,sender_port,conninfo}',
+  proallargtypes => '{int4,text,pg_lsn,int4,pg_lsn,pg_lsn,int4,timestamptz,timestamptz,pg_lsn,timestamptz,text,text,int4,text}',
+  proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{pid,status,receive_start_lsn,receive_start_tli,written_lsn,flushed_lsn,received_tli,last_msg_send_time,last_msg_receipt_time,latest_end_lsn,latest_end_time,slot_name,sender_host,sender_port,conninfo}',
   prosrc => 'pg_stat_get_wal_receiver' },
 { oid => '6118', descr => 'statistics: information about subscription',
   proname => 'pg_stat_get_subscription', proisstrict => 'f', provolatile => 's',

src/test/regress/expected/rules.out

@@ -2124,7 +2124,8 @@ pg_stat_wal_receiver| SELECT s.pid,
     s.status,
     s.receive_start_lsn,
     s.receive_start_tli,
-    s.received_lsn,
+    s.written_lsn,
+    s.flushed_lsn,
     s.received_tli,
     s.last_msg_send_time,
     s.last_msg_receipt_time,
@@ -2134,7 +2135,7 @@ pg_stat_wal_receiver| SELECT s.pid,
     s.sender_host,
     s.sender_port,
     s.conninfo
-   FROM pg_stat_get_wal_receiver() s(pid, status, receive_start_lsn, receive_start_tli, received_lsn, received_tli, last_msg_send_time, last_msg_receipt_time, latest_end_lsn, latest_end_time, slot_name, sender_host, sender_port, conninfo)
+   FROM pg_stat_get_wal_receiver() s(pid, status, receive_start_lsn, receive_start_tli, written_lsn, flushed_lsn, received_tli, last_msg_send_time, last_msg_receipt_time, latest_end_lsn, latest_end_time, slot_name, sender_host, sender_port, conninfo)
   WHERE (s.pid IS NOT NULL);
 pg_stat_xact_all_tables| SELECT c.oid AS relid,
     n.nspname AS schemaname,