From fbd9fa407c04799ad4401d3ba5c6b67a0d922631 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Tue, 31 Oct 2023 10:14:01 +0900
Subject: [PATCH] Force crash recovery with backup_label and no .signal files

---
 src/backend/access/transam/xlogrecovery.c    | 29 ++++++++++++++++----
 src/bin/pg_basebackup/t/010_pg_basebackup.pl |  3 +-
 doc/src/sgml/backup.sgml                     |  4 ++-
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index c61566666a..de5787d7e8 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -133,6 +133,8 @@ static TimeLineID curFileTLI;
  * currently performing crash recovery using only XLOG files in pg_wal, but
  * will switch to using offline XLOG archives as soon as we reach the end of
  * WAL in pg_wal.
+ *
+ * InArchiveRecovery should never be set without ArchiveRecoveryRequested.
  */
 bool		ArchiveRecoveryRequested = false;
 bool		InArchiveRecovery = false;
@@ -595,13 +597,22 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 		List	   *tablespaces = NIL;
 
 		/*
-		 * Archive recovery was requested, and thanks to the backup label
-		 * file, we know how far we need to replay to reach consistency. Enter
-		 * archive recovery directly.
+		 * If archive recovery was requested, and we know how far we need to
+		 * replay to reach consistency thanks to the backup label file, then
+		 * enter archive recovery directly in this case.
+		 *
+		 * If archive recovery was not requested, then do crash recovery and
+		 * replay all the local WAL.  This still checks that all the WAL up
+		 * to backupEndRequired has been replayed.  This case is useful when
+		 * restoring from a standalone base backup, taken with pg_basebackup
+		 * --wal-method=stream, for example.
 		 */
-		InArchiveRecovery = true;
-		if (StandbyModeRequested)
-			EnableStandbyMode();
+		if (ArchiveRecoveryRequested)
+		{
+			InArchiveRecovery = true;
+			if (StandbyModeRequested)
+				EnableStandbyMode();
+		}
 
 		/*
 		 * When a backup_label file is present, we want to roll forward from
@@ -1591,6 +1602,12 @@ ShutdownWalRecovery(void)
 	 */
 	if (ArchiveRecoveryRequested)
 		DisownLatch(&XLogRecoveryCtl->recoveryWakeupLatch);
+
+	/*
+	 * InArchiveRecovery should never have been set without
+	 * ArchiveRecoveryRequested.
+	 */
+	Assert(ArchiveRecoveryRequested || !InArchiveRecovery);
 }
 
 /*
diff --git a/src/bin/pg_basebackup/t/010_pg_basebackup.pl b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
index b9f5e1266b..b9e54f4562 100644
--- a/src/bin/pg_basebackup/t/010_pg_basebackup.pl
+++ b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
@@ -392,7 +392,8 @@ SKIP:
 	my $node2 = PostgreSQL::Test::Cluster->new('replica');
 
 	# Recover main data directory
-	$node2->init_from_backup($node, 'tarbackup2', tar_program => $tar);
+	$node2->init_from_backup($node, 'tarbackup2', tar_program => $tar,
+	    has_restoring => 1);
 
 	# Recover tablespace into a new directory (not where it was!)
 	my $repTsDir = "$tempdir/tblspc1replica";
diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index 8cb24d6ae5..5ba7a284cf 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -1380,7 +1380,9 @@ restore_command = 'cp /mnt/server/archivedir/%f %p'
       tool. If you include the <literal>-X</literal> parameter when calling
       it, all the write-ahead log required to use the backup will be
       included in the backup automatically, and no special action is
-      required to restore the backup.
+      required to restore the backup. Restoring a standalone backup is
+      equivalent to crash recovery, replaying all the WAL stored in
+      <filename>pg_wal</filename> up to its end.
      </para>
     </sect3>
 
-- 
2.42.0