Subject: Re: Add recovery to pg_control and remove backup_label

From: Michael Paquier <[email-masked]>
Date: Fri, 10 Nov 2023 13:37:00 +0900

On Tue, Nov 07, 2023 at 05:20:27PM +0900, Michael Paquier wrote:
> On Mon, Nov 06, 2023 at 05:39:02PM -0400, David Steele wrote:
> I've retested today, and miss the failure.  I'll let you know if I see
> this again.

I've done a few more dozen runs, and still nothing.  I am wondering
what this disturbance was.

>> If we set these fields where backup_label was renamed, the logic would not
>> be exactly the same since pg_control won't be updated until the next time
>> through the loop. Since the fields should be updated before
>> UpdateControlFile() I thought it made sense to keep all the updates
>> together.
>> 
>> Overall I think it is simpler, and we don't need to acquire a lock on
>> ControlFile.
> 
> What you are proposing is the same as what we already do for
> backupEndRequired or backupStartPoint in the control file when
> initializing recovery, so objection withdrawn.
> 
>> Thomas included this change in his pg_basebackup changes so I did the same.
>> Maybe wait a bit before we split this out? Seems like a pretty small
>> change...
> 
> Seems like a pretty good argument for refactoring that now, and let
> any other patches rely on it.  Would you like to send a separate
> patch?

The split still looks worth doing seen from here, so I am switching
the patch as WoA for now.

>>> Actually, grouping backupStartPointTLI and minRecoveryPointTLI should
>>> reduce more the size with some alignment magic, no?
>> 
>> I thought about this, but it seemed to me that existing fields had been
>> positioned to make the grouping logical rather than to optimize alignment,
>> e.g. minRecoveryPointTLI. Ideally that would have been placed near
>> backupEndRequired (or vice versa). But if the general opinion is to
>> rearrange for alignment, I'm OK with that.
> 
> I've not tested, but it looks like moving backupStartPointTLI after
> backupEndPoint should shave 8 bytes, if you want to maintain a more
> coherent group for the LSNs.

+    * backupFromStandby indicates that the backup was taken on a standby. It is
+    * require to initialize recovery and set to false afterwards.
s/require/required/.

The term "backup recovery", that we've never used in the tree until
now as far as I know.  Perhaps this recovery method should just be
referred as "recovery from backup"?

By the way, there is another thing that this patch has forgotten: the
SQL functions that display data from the control file.  Shouldn't
pg_control_recovery() be extended with the new fields?  These fields
may be less critical than the other ones related to recovery, but I
suspect that showing them can become handy at least for debugging and
monitoring purposes.

Something in this area is that backupRecoveryRequired is the switch
controlling if the fields set by the recovery initialization.  Could
it be actually useful to leave the other fields as they are and only
reset backupRecoveryRequired before the first control file update?
This would leave a trace of the backup history directly in the control
file.

What about pg_resetwal and RewriteControlFile()?  Shouldn't these
recovery fields be reset as well?

git diff --check is complaining a bit.
--
Michael

---

From: David Steele <[email-masked]>
Date: Fri, 10 Nov 2023 14:55:19 -0400

> what this disturbance was.

OK, hopefully it was just a blip.

> the patch as WoA for now.

This has been split out.

>> coherent group for the LSNs.

OK, I have moved backupStartPointTLI.

> +    * require to initialize recovery and set to false afterwards.

Fixed.

> referred as "recovery from backup"?

Well, "backup recovery" is less awkward, I think. For instance "backup 
recovery field" vs "recovery from backup field".

> suspect that showing them can become handy at least for debugging and

I guess that depends on whether we reset them or not (discussion below). 
Right now they would not be visible since by the time the user could log 
on they would be reset.

> This would leave a trace of the backup history directly in the control

Since the other recovery fields are cleared in ReachedEndOfBackup() this 
would be a change from what we do now.

None of these fields are ever visible (with the exception of 
minRecoveryPoint/TLI) since they are reset when the database becomes 
consistent and before logons are allowed. Viewing them with 
pg_controldata makes sense, but I'm not sure pg_control_recovery() does.

In fact, are backup_start_lsn, backup_end_lsn, and 
end_of_backup_record_required ever non-zero when logged onto Postgres? 
Maybe I'm missing something?

> recovery fields be reset as well?

Done.

> git diff --check is complaining a bit.

Fixed.

New patches attached based on eb81e8e790.

Regards,
-David

From d241a0e8aa589b3abf66331f8a3af0aabe87c214 Mon Sep 17 00:00:00 2001
From: David Steele <[email-masked]>
Date: Fri, 10 Nov 2023 17:50:54 +0000
Subject: Allow content size to be passed to sendFileWithContent().

sendFileWithContent() previously got the content length by using strlen(),
but it is also possible to pass binary content. Use len == -1 to indicate
that strlen() should be use to get the content length, otherwise honor the
value in len.
---
 src/backend/backup/basebackup.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/backend/backup/basebackup.c b/src/backend/backup/basebackup.c
index b537f462197..f216b588422 100644
--- a/src/backend/backup/basebackup.c
+++ b/src/backend/backup/basebackup.c
@@ -94,7 +94,7 @@ static bool verify_page_checksum(Page page, XLogRecPtr start_lsn,
 								 BlockNumber blkno,
 								 uint16 *expected_checksum);
 static void sendFileWithContent(bbsink *sink, const char *filename,
-								const char *content,
+								const char *content, int len,
 								backup_manifest_info *manifest);
 static int64 _tarWriteHeader(bbsink *sink, const char *filename,
 							 const char *linktarget, struct stat *statbuf,
@@ -334,14 +334,14 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 				/* In the main tar, include the backup_label first... */
 				backup_label = build_backup_content(backup_state, false);
 				sendFileWithContent(sink, BACKUP_LABEL_FILE,
-									backup_label, &manifest);
+									backup_label, -1, &manifest);
 				pfree(backup_label);
 
 				/* Then the tablespace_map file, if required... */
 				if (opt->sendtblspcmapfile)
 				{
 					sendFileWithContent(sink, TABLESPACE_MAP,
-										tablespace_map->data, &manifest);
+										tablespace_map->data, -1, &manifest);
 					sendtblspclinks = false;
 				}
 
@@ -601,7 +601,7 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 			 * complete segment.
 			 */
 			StatusFilePath(pathbuf, walFileName, ".done");
-			sendFileWithContent(sink, pathbuf, "", &manifest);
+			sendFileWithContent(sink, pathbuf, "", -1, &manifest);
 		}
 
 		/*
@@ -629,7 +629,7 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 
 			/* unconditionally mark file as archived */
 			StatusFilePath(pathbuf, fname, ".done");
-			sendFileWithContent(sink, pathbuf, "", &manifest);
+			sendFileWithContent(sink, pathbuf, "", -1, &manifest);
 		}
 
 		/* Properly terminate the tar file. */
@@ -1040,22 +1040,22 @@ SendBaseBackup(BaseBackupCmd *cmd)
  */
 static void
 sendFileWithContent(bbsink *sink, const char *filename, const char *content,
-					backup_manifest_info *manifest)
+					int len, backup_manifest_info *manifest)
 {
 	struct stat statbuf;
-	int			bytes_done = 0,
-				len;
+	int			bytes_done = 0;
 	pg_checksum_context checksum_ctx;
 
 	if (pg_checksum_init(&checksum_ctx, manifest->checksum_type) < 0)
 		elog(ERROR, "could not initialize checksum of file \"%s\"",
 			 filename);
 
-	len = strlen(content);
+	/* If len less than zero treat content as a string */
+	if (len < 0)
+		len = strlen(content);
 
 	/*
-	 * Construct a stat struct for the backup_label file we're injecting in
-	 * the tar.
+	 * Construct a stat struct for the file we're injecting in the tar.
 	 */
 	/* Windows doesn't have the concept of uid and gid */
 #ifdef WIN32
-- 
2.34.1

From 79c33f300dd5bb9aabd08f27d2e6bb5857190524 Mon Sep 17 00:00:00 2001
From: David Steele <[email-masked]>
Date: Fri, 10 Nov 2023 17:50:55 +0000
Subject: Add recovery to pg_control and remove backup_label.

Simplify and harden recovery by getting rid of backup_label and storing
recovery information directly in pg_control. Instead of backup software copying
pg_control from PGDATA, it stores an updated version that is returned from
pg_backup_stop(). This is better for the following reasons:

* The user can no longer remove backup_label and get what looks like a
successful restore (while almost certainly causing corruption). If pg_control
is removed the cluster will not start. The user may try pg_resetwal, but I
think that tool makes it pretty clear that corruption will result from its use.
We could also modify pg_resetwal to complain if recovery info is present in
pg_control.

* We don't need to worry about backup software seeing a torn copy of pg_control,
since Postgres can safely read it out of memory and provide a valid copy via
pg_backup_stop(). This solves [2] without needing to write pg_control via a temp
file, which may affect performance on a standby. Unfortunately, this solution
cannot be back patched.

* For backup from standby, we no longer need to instruct the backup software to
copy pg_control last. In fact the backup software should not copy pg_control from
PGDATA at all.

Since backup_label is now gone, the fields that used to be in backup_label are
now provided as columns returned from pg_backup_start() and pg_backup_stop() and
the backup history file is still written to the archive.
---
 doc/src/sgml/backup.sgml                     |  31 ++-
 doc/src/sgml/func.sgml                       |  39 ++-
 doc/src/sgml/ref/pg_rewind.sgml              |   3 +-
 src/backend/access/transam/xlog.c            |  64 ++---
 src/backend/access/transam/xlogbackup.c      |  39 ++-
 src/backend/access/transam/xlogfuncs.c       |  50 ++--
 src/backend/access/transam/xlogrecovery.c    | 250 ++++---------------
 src/backend/backup/basebackup.c              |  35 +--
 src/backend/catalog/system_functions.sql     |  10 +-
 src/bin/pg_basebackup/t/010_pg_basebackup.pl |  15 +-
 src/bin/pg_controldata/pg_controldata.c      |   8 +
 src/bin/pg_resetwal/pg_resetwal.c            |   4 +
 src/bin/pg_rewind/filemap.c                  |   7 +-
 src/bin/pg_rewind/pg_rewind.c                |  62 +----
 src/include/access/xlog.h                    |   2 -
 src/include/access/xlogbackup.h              |  14 +-
 src/include/access/xlogrecovery.h            |   3 +-
 src/include/catalog/pg_control.h             |  18 +-
 src/include/catalog/pg_proc.dat              |  10 +-
 19 files changed, 268 insertions(+), 396 deletions(-)

diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index 8cb24d6ae54..584384875be 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -935,19 +935,20 @@ SELECT * FROM pg_backup_stop(wait_for_archive => true);
      ready to archive.
     </para>
     <para>
-     <function>pg_backup_stop</function> will return one row with three
-     values. The second of these fields should be written to a file named
-     <filename>backup_label</filename> in the root directory of the backup. The
-     third field should be written to a file named
-     <filename>tablespace_map</filename> unless the field is empty. These files are
+     <function>pg_backup_stop</function> returns the
+     <filename>pg_control</filename> file, which must be stored in the
+     <filename>global</filename> directory of the backup. It also returns the
+     <filename>tablespace_map</filename> file, which should be written in the
+     root directory of the backup unless the field is empty. These files are
      vital to the backup working and must be written byte for byte without
-     modification, which may require opening the file in binary mode.
+     modification, which will require opening the file in binary mode.
     </para>
    </listitem>
    <listitem>
     <para>
      Once the WAL segment files active during the backup are archived, you are
-     done.  The file identified by <function>pg_backup_stop</function>'s first return
+     done.  The file identified by <function>pg_backup_stop</function>'s
+     <parameter>lsn</parameter> return
      value is the last segment that is required to form a complete set of
      backup files.  On a primary, if <varname>archive_mode</varname> is enabled and the
      <literal>wait_for_archive</literal> parameter is <literal>true</literal>,
@@ -1013,7 +1014,15 @@ SELECT * FROM pg_backup_stop(wait_for_archive => true);
    </para>
 
    <para>
-    You should, however, omit from the backup the files within the
+    You must exclude <filename>global/pg_control</filename> from your backup
+    and put the contents of the <parameter>pg_control_file</parameter> column
+    returned from <function>pg_backup_stop</function> in your backup at
+    <filename>global/pg_control</filename>. This file contains the information
+    required to safely recover.
+   </para>
+
+   <para>
+    You should also omit from the backup the files within the
     cluster's <filename>pg_wal/</filename> subdirectory.  This
     slight adjustment is worthwhile because it reduces the risk
     of mistakes when restoring.  This is easy to arrange if
@@ -1062,11 +1071,11 @@ SELECT * FROM pg_backup_stop(wait_for_archive => true);
    </para>
 
    <para>
-    The backup label
-    file includes the label string you gave to <function>pg_backup_start</function>,
+    The backup history file (which is archived like WAL) includes the label
+    string you gave to <function>pg_backup_start</function>,
     as well as the time at which <function>pg_backup_start</function> was run, and
     the name of the starting WAL file.  In case of confusion it is therefore
-    possible to look inside a backup file and determine exactly which
+    possible to look inside a backup history file and determine exactly which
     backup session the dump file came from.  The tablespace map file includes
     the symbolic link names as they exist in the directory
     <filename>pg_tblspc/</filename> and the full path of each symbolic link.
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index d963f0a0a00..ed3e5b9dce6 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -26845,7 +26845,10 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
           <parameter>label</parameter> <type>text</type>
           <optional>, <parameter>fast</parameter> <type>boolean</type>
           </optional> )
-        <returnvalue>pg_lsn</returnvalue>
+        <returnvalue>record</returnvalue>
+        ( <parameter>lsn</parameter> <type>pg_lsn</type>,
+        <parameter>timeline_id</parameter> <type>int8</type>,
+        <parameter>start</parameter> <type>timestamptz</type> )
        </para>
        <para>
         Prepares the server to begin an on-line backup.  The only required
@@ -26857,6 +26860,13 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
         as possible.  This forces an immediate checkpoint which will cause a
         spike in I/O operations, slowing any concurrently executing queries.
        </para>
+       <para>
+        The result columns contain information about the start of the backup
+        and can be ignored: the <parameter>lsn</parameter> column holds the
+        starting write-ahead log location, the
+        <parameter>timeline_id</parameter> column holds the starting timeline,
+        and the <parameter>stop</parameter> column holds the starting timestamp.
+       </para>
        <para>
         This function is restricted to superusers by default, but other users
         can be granted EXECUTE to run the function.
@@ -26872,13 +26882,15 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
           <optional><parameter>wait_for_archive</parameter> <type>boolean</type>
           </optional> )
         <returnvalue>record</returnvalue>
-        ( <parameter>lsn</parameter> <type>pg_lsn</type>,
-        <parameter>labelfile</parameter> <type>text</type>,
-        <parameter>spcmapfile</parameter> <type>text</type> )
+        ( <parameter>pg_control_file</parameter> <type>text</type>,
+        <parameter>tablespace_map_file</parameter> <type>text</type>,
+        <parameter>lsn</parameter> <type>pg_lsn</type>,
+        <parameter>timeline_id</parameter> <type>int8</type>,
+        <parameter>stop</parameter> <type>timestamptz</type> )
        </para>
        <para>
         Finishes performing an on-line backup.  The desired contents of the
-        backup label file and the tablespace map file are returned as part of
+        pg_control file and the tablespace map file are returned as part of
         the result of the function and must be written to files in the
         backup area.  These files must not be written to the live data directory
         (doing so will cause PostgreSQL to fail to restart in the event of a
@@ -26910,13 +26922,16 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
         backup.
        </para>
        <para>
-        The result of the function is a single record.
-        The <parameter>lsn</parameter> column holds the backup's ending
-        write-ahead log location (which again can be ignored).  The second
-        column returns the contents of the backup label file, and the third
-        column returns the contents of the tablespace map file.  These must be
-        stored as part of the backup and are required as part of the restore
-        process.
+        The result of the function is a single record. The first column returns
+        the contents of the <filename>pg_control</filename> file and the
+        second column returns the contents of the
+        <filename>tablespace_map</filename> file.  These must be stored as part
+        of the backup and are required as part of the restore process. The
+        remainder of the columns contain information about the end of the backup
+        and can be ignored: the <parameter>lsn</parameter> column holds the
+        ending write-ahead log location, the <parameter>timeline_id</parameter>
+        column holds the ending timeline, and the <parameter>stop</parameter>
+        column holds the ending timestamp.
        </para>
        <para>
         This function is restricted to superusers by default, but other users
diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 8e0000d39fb..889add4c5e4 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -400,7 +400,6 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       <filename>pg_serial/</filename>, <filename>pg_snapshots/</filename>,
       <filename>pg_stat_tmp/</filename>, and <filename>pg_subtrans/</filename>
       are omitted from the data copied from the source cluster. The files
-      <filename>backup_label</filename>,
       <filename>tablespace_map</filename>,
       <filename>pg_internal.init</filename>,
       <filename>postmaster.opts</filename>, and
@@ -410,7 +409,7 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
     </step>
     <step>
      <para>
-      Create a <filename>backup_label</filename> file to begin WAL replay at
+      Update <filename>pg_control</filename> file to begin WAL replay at
       the checkpoint created at failover and configure the
       <filename>pg_control</filename> file with a minimum consistency LSN
       defined as the result of <literal>pg_current_wal_insert_lsn()</literal>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 1159dff1a69..1689bc7d3a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -74,6 +74,7 @@
 #include "pg_trace.h"
 #include "pgstat.h"
 #include "port/atomics.h"
+#include "port/pg_crc32c.h"
 #include "port/pg_iovec.h"
 #include "postmaster/bgwriter.h"
 #include "postmaster/startup.h"
@@ -5135,7 +5136,6 @@ StartupXLOG(void)
 	bool		wasShutdown;
 	bool		didCrash;
 	bool		haveTblspcMap;
-	bool		haveBackupLabel;
 	XLogRecPtr	EndOfLog;
 	TimeLineID	EndOfLogTLI;
 	TimeLineID	newTLI;
@@ -5259,13 +5259,14 @@ StartupXLOG(void)
 	/*
 	 * Prepare for WAL recovery if needed.
 	 *
-	 * InitWalRecovery analyzes the control file and the backup label file, if
-	 * any.  It updates the in-memory ControlFile buffer according to the
-	 * starting checkpoint, and sets InRecovery and ArchiveRecoveryRequested.
+	 * InitWalRecovery analyzes the control file and checks if backup recovery
+	 * has been requested.  It updates the in-memory ControlFile buffer
+	 * according to the starting checkpoint, and sets InRecovery and
+	 * ArchiveRecoveryRequested.
+	 *
 	 * It also applies the tablespace map file, if any.
 	 */
-	InitWalRecovery(ControlFile, &wasShutdown,
-					&haveBackupLabel, &haveTblspcMap);
+	InitWalRecovery(ControlFile, &wasShutdown, &haveTblspcMap);
 	checkPoint = ControlFile->checkPointCopy;
 
 	/* initialize shared memory variables from the checkpoint record */
@@ -5408,20 +5409,6 @@ StartupXLOG(void)
 		 */
 		UpdateControlFile();
 
-		/*
-		 * If there was a backup label file, it's done its job and the info
-		 * has now been propagated into pg_control.  We must get rid of the
-		 * label file so that if we crash during recovery, we'll pick up at
-		 * the latest recovery restartpoint instead of going all the way back
-		 * to the backup start point.  It seems prudent though to just rename
-		 * the file out of the way rather than delete it completely.
-		 */
-		if (haveBackupLabel)
-		{
-			unlink(BACKUP_LABEL_OLD);
-			durable_rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD, FATAL);
-		}
-
 		/*
 		 * If there was a tablespace_map file, it's done its job and the
 		 * symlinks have been created.  We must get rid of the map file so
@@ -5571,10 +5558,8 @@ StartupXLOG(void)
 	 * (at which point we reset backupStartPoint to be Invalid), for
 	 * backup-from-replica (which can't inject records into the WAL stream),
 	 * that point is when we reach the minRecoveryPoint in pg_control (which
-	 * we purposefully copy last when backing up from a replica).  For
-	 * pg_rewind (which creates a backup_label with a method of "pg_rewind")
-	 * or snapshot-style backups (which don't), backupEndRequired will be set
-	 * to false.
+	 * we purposefully copy last when backing up).  For pg_rewind or
+	 * snapshot-style backups, backupEndRequired will be set to false.
 	 *
 	 * Note: it is indeed okay to look at the local variable
 	 * LocalMinRecoveryPoint here, even though ControlFile->minRecoveryPoint
@@ -8744,11 +8729,33 @@ do_pg_backup_stop(BackupState *state, bool waitforarchive)
 	int			seconds_before_warning;
 	int			waits = 0;
 	bool		reported_waiting = false;
+	ControlFileData *controlFileCopy = (ControlFileData *)state->controlFile;
 
 	Assert(state != NULL);
 
 	backup_stopped_in_recovery = RecoveryInProgress();
 
+	/*
+	 * Create a copy of control data and update it with fields required for
+	 * recovery. Also recalculate the CRC.
+	 */
+	memset(controlFileCopy, 0, PG_CONTROL_MAX_SAFE_SIZE);
+
+	LWLockAcquire(ControlFileLock, LW_SHARED);
+	memcpy(controlFileCopy, ControlFile, sizeof(ControlFileData));
+	LWLockRelease(ControlFileLock);
+
+	controlFileCopy->backupRecoveryRequired = true;
+	controlFileCopy->backupFromStandby = backup_stopped_in_recovery;
+	controlFileCopy->backupEndRequired = true;
+	controlFileCopy->backupCheckPoint = state->checkpointloc;
+	controlFileCopy->backupStartPoint = state->startpoint;
+	controlFileCopy->backupStartPointTLI = state->starttli;
+
+	INIT_CRC32C(controlFileCopy->crc);
+	COMP_CRC32C(controlFileCopy->crc, controlFileCopy, offsetof(ControlFileData, crc));
+	FIN_CRC32C(controlFileCopy->crc);
+
 	/*
 	 * During recovery, we don't need to check WAL level. Because, if WAL
 	 * level is not sufficient, it's impossible to get here during recovery.
@@ -8850,11 +8857,8 @@ do_pg_backup_stop(BackupState *state, bool waitforarchive)
 							 "Enable full_page_writes and run CHECKPOINT on the primary, "
 							 "and then try an online backup again.")));
 
-
-		LWLockAcquire(ControlFileLock, LW_SHARED);
-		state->stoppoint = ControlFile->minRecoveryPoint;
-		state->stoptli = ControlFile->minRecoveryPointTLI;
-		LWLockRelease(ControlFileLock);
+		state->stoppoint = controlFileCopy->minRecoveryPoint;
+		state->stoptli = controlFileCopy->minRecoveryPointTLI;
 	}
 	else
 	{
@@ -8896,7 +8900,7 @@ do_pg_backup_stop(BackupState *state, bool waitforarchive)
 							histfilepath)));
 
 		/* Build and save the contents of the backup history file */
-		history_file = build_backup_content(state, true);
+		history_file = build_backup_history_content(state);
 		fprintf(fp, "%s", history_file);
 		pfree(history_file);
 
diff --git a/src/backend/access/transam/xlogbackup.c b/src/backend/access/transam/xlogbackup.c
index 21d68133ae1..22c95f3c4c9 100644
--- a/src/backend/access/transam/xlogbackup.c
+++ b/src/backend/access/transam/xlogbackup.c
@@ -18,19 +18,19 @@
 #include "access/xlogbackup.h"
 
 /*
- * Build contents for backup_label or backup history file.
- *
- * When ishistoryfile is true, it creates the contents for a backup history
- * file, otherwise it creates contents for a backup_label file.
+ * Build contents for backup history file.
  *
  * Returns the result generated as a palloc'd string.
  */
 char *
-build_backup_content(BackupState *state, bool ishistoryfile)
+build_backup_history_content(BackupState *state)
 {
 	char		startstrbuf[128];
+	char		stopstrfbuf[128];
 	char		startxlogfile[MAXFNAMELEN]; /* backup start WAL file */
+	char		stopxlogfile[MAXFNAMELEN];	/* backup stop WAL file */
 	XLogSegNo	startsegno;
+	XLogSegNo	stopsegno;
 	StringInfo	result = makeStringInfo();
 	char	   *data;
 
@@ -45,16 +45,10 @@ build_backup_content(BackupState *state, bool ishistoryfile)
 	appendStringInfo(result, "START WAL LOCATION: %X/%X (file %s)\n",
 					 LSN_FORMAT_ARGS(state->startpoint), startxlogfile);
 
-	if (ishistoryfile)
-	{
-		char		stopxlogfile[MAXFNAMELEN];	/* backup stop WAL file */
-		XLogSegNo	stopsegno;
-
-		XLByteToSeg(state->stoppoint, stopsegno, wal_segment_size);
-		XLogFileName(stopxlogfile, state->stoptli, stopsegno, wal_segment_size);
-		appendStringInfo(result, "STOP WAL LOCATION: %X/%X (file %s)\n",
-						 LSN_FORMAT_ARGS(state->stoppoint), stopxlogfile);
-	}
+	XLByteToSeg(state->stoppoint, stopsegno, wal_segment_size);
+	XLogFileName(stopxlogfile, state->stoptli, stopsegno, wal_segment_size);
+	appendStringInfo(result, "STOP WAL LOCATION: %X/%X (file %s)\n",
+						LSN_FORMAT_ARGS(state->stoppoint), stopxlogfile);
 
 	appendStringInfo(result, "CHECKPOINT LOCATION: %X/%X\n",
 					 LSN_FORMAT_ARGS(state->checkpointloc));
@@ -65,17 +59,12 @@ build_backup_content(BackupState *state, bool ishistoryfile)
 	appendStringInfo(result, "LABEL: %s\n", state->name);
 	appendStringInfo(result, "START TIMELINE: %u\n", state->starttli);
 
-	if (ishistoryfile)
-	{
-		char		stopstrfbuf[128];
-
-		/* Use the log timezone here, not the session timezone */
-		pg_strftime(stopstrfbuf, sizeof(stopstrfbuf), "%Y-%m-%d %H:%M:%S %Z",
-					pg_localtime(&state->stoptime, log_timezone));
+	/* Use the log timezone here, not the session timezone */
+	pg_strftime(stopstrfbuf, sizeof(stopstrfbuf), "%Y-%m-%d %H:%M:%S %Z",
+				pg_localtime(&state->stoptime, log_timezone));
 
-		appendStringInfo(result, "STOP TIME: %s\n", stopstrfbuf);
-		appendStringInfo(result, "STOP TIMELINE: %u\n", state->stoptli);
-	}
+	appendStringInfo(result, "STOP TIME: %s\n", stopstrfbuf);
+	appendStringInfo(result, "STOP TIMELINE: %u\n", state->stoptli);
 
 	data = result->data;
 	pfree(result);
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
index 45a70668b1c..2388a60a5e5 100644
--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -53,7 +53,7 @@ static MemoryContext backupcontext = NULL;
  * pg_backup_start: set up for taking an on-line backup dump
  *
  * Essentially what this does is to create the contents required for the
- * backup_label file and the tablespace map.
+ * the tablespace map.
  *
  * Permission checking for this function is managed through the normal
  * GRANT system.
@@ -61,6 +61,10 @@ static MemoryContext backupcontext = NULL;
 Datum
 pg_backup_start(PG_FUNCTION_ARGS)
 {
+#define PG_BACKUP_START_V2_COLS 3
+	TupleDesc	tupdesc;
+	Datum		values[PG_BACKUP_START_V2_COLS] = {0};
+	bool		nulls[PG_BACKUP_START_V2_COLS] = {0};
 	text	   *backupid = PG_GETARG_TEXT_PP(0);
 	bool		fast = PG_GETARG_BOOL(1);
 	char	   *backupidstr;
@@ -69,6 +73,10 @@ pg_backup_start(PG_FUNCTION_ARGS)
 
 	backupidstr = text_to_cstring(backupid);
 
+	/* Initialize attributes information in the tuple descriptor */
+	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+		elog(ERROR, "return type must be a row type");
+
 	if (status == SESSION_BACKUP_RUNNING)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
@@ -102,7 +110,12 @@ pg_backup_start(PG_FUNCTION_ARGS)
 	register_persistent_abort_backup_handler();
 	do_pg_backup_start(backupidstr, fast, NULL, backup_state, tablespace_map);
 
-	PG_RETURN_LSN(backup_state->startpoint);
+	values[0] = LSNGetDatum(backup_state->startpoint);
+	values[1] = Int64GetDatum(backup_state->starttli);
+	values[2] = TimestampTzGetDatum(time_t_to_timestamptz(backup_state->starttime));
+
+	/* Returns the record as Datum */
+	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
 }

@@ -113,14 +126,12 @@ pg_backup_start(PG_FUNCTION_ARGS)
  * allows the user to choose if they want to wait for the WAL to be archived
  * or if we should just return as soon as the WAL record is written.
  *
- * This function stops an in-progress backup, creates backup_label contents and
- * it returns the backup stop LSN, backup_label and tablespace_map contents.
+ * This function stops an in-progress backup and returns the backup stop LSN,
+ * pg_control and tablespace_map contents.
  *
- * The backup_label contains the user-supplied label string (typically this
- * would be used to tell where the backup dump will be stored), the starting
- * time, starting WAL location for the dump and so on.  It is the caller's
- * responsibility to write the backup_label and tablespace_map files in the
- * data folder that will be restored from this backup.
+ * The pg_control file contains the recovery information for the backup.  It is
+ * the caller's responsibility to write the pg_control and tablespace_map files
+ * in the data folder that will be restored from this backup.
  *
  * Permission checking for this function is managed through the normal
  * GRANT system.
@@ -128,12 +139,12 @@ pg_backup_start(PG_FUNCTION_ARGS)
 Datum
 pg_backup_stop(PG_FUNCTION_ARGS)
 {
-#define PG_BACKUP_STOP_V2_COLS 3
+#define PG_BACKUP_STOP_V2_COLS 5
 	TupleDesc	tupdesc;
 	Datum		values[PG_BACKUP_STOP_V2_COLS] = {0};
 	bool		nulls[PG_BACKUP_STOP_V2_COLS] = {0};
 	bool		waitforarchive = PG_GETARG_BOOL(0);
-	char	   *backup_label;
+	bytea	   *pg_control_bytea;
 	SessionBackupState status = get_backup_status();
 
 	/* Initialize attributes information in the tuple descriptor */
@@ -152,15 +163,16 @@ pg_backup_stop(PG_FUNCTION_ARGS)
 	/* Stop the backup */
 	do_pg_backup_stop(backup_state, waitforarchive);
 
-	/* Build the contents of backup_label */
-	backup_label = build_backup_content(backup_state, false);
-
-	values[0] = LSNGetDatum(backup_state->stoppoint);
-	values[1] = CStringGetTextDatum(backup_label);
-	values[2] = CStringGetTextDatum(tablespace_map->data);
+	/* Build the contents of pg_control */
+	pg_control_bytea = (bytea *) palloc(PG_CONTROL_MAX_SAFE_SIZE + VARHDRSZ);
+	SET_VARSIZE(pg_control_bytea, PG_CONTROL_MAX_SAFE_SIZE + VARHDRSZ);
+	memcpy(VARDATA(pg_control_bytea), backup_state->controlFile, PG_CONTROL_MAX_SAFE_SIZE);
 
-	/* Deallocate backup-related variables */
-	pfree(backup_label);
+	values[0] = PointerGetDatum(pg_control_bytea);
+	values[1] = CStringGetTextDatum(tablespace_map->data);
+	values[2] = LSNGetDatum(backup_state->stoppoint);
+	values[3] = Int64GetDatum(backup_state->stoptli);
+	values[4] = TimestampTzGetDatum(time_t_to_timestamptz(backup_state->stoptime));
 
 	/* Clean up the session-level state and its memory context */
 	backup_state = NULL;
diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index c61566666aa..f43ea39f963 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -6,7 +6,7 @@
  * This source file contains functions controlling WAL recovery.
  * InitWalRecovery() initializes the system for crash or archive recovery,
  * or standby mode, depending on configuration options and the state of
- * the control file and possible backup label file.  PerformWalRecovery()
+ * the control file and possible backup recovery.  PerformWalRecovery()
  * performs the actual WAL replay, calling the rmgr-specific redo routines.
  * FinishWalRecovery() performs end-of-recovery checks and cleanup actions,
  * and prepares information needed to initialize the WAL for writes.  In
@@ -152,11 +152,12 @@ static bool recovery_signal_file_found = false;
 
 /*
  * CheckPointLoc is the position of the checkpoint record that determines
- * where to start the replay.  It comes from the backup label file or the
- * control file.
+ * where to start the replay.  It comes from the control file, either from the
+ * default location or from a backup recovery field.
  *
- * RedoStartLSN is the checkpoint's REDO location, also from the backup label
- * file or the control file.  In standby mode, XLOG streaming usually starts
+ * RedoStartLSN is the checkpoint's REDO location, also from the default
+ * control file location or from a backup recovery field.  In standby mode,
+ * XLOG streaming usually starts
  * from the position where an invalid record was found.  But if we fail to
  * read even the initial checkpoint record, we use the REDO location instead
  * of the checkpoint location as the start position of XLOG streaming.
@@ -388,9 +389,6 @@ static void ApplyWalRecord(XLogReaderState *xlogreader, XLogRecord *record, Time
 static void EnableStandbyMode(void);
 static void readRecoverySignalFile(void);
 static void validateRecoveryParameters(void);
-static bool read_backup_label(XLogRecPtr *checkPointLoc,
-							  TimeLineID *backupLabelTLI,
-							  bool *backupEndRequired, bool *backupFromStandby);
 static bool read_tablespace_map(List **tablespaces);
 
 static void xlogrecovery_redo(XLogReaderState *record, TimeLineID replayTLI);
@@ -492,8 +490,8 @@ EnableStandbyMode(void)
  * Prepare the system for WAL recovery, if needed.
  *
  * This is called by StartupXLOG() which coordinates the server startup
- * sequence.  This function analyzes the control file and the backup label
- * file, if any, and figures out whether we need to perform crash recovery or
+ * sequence.  This function analyzes the control file and backup recovery
+ * info, if any, and figures out whether we need to perform crash recovery or
  * archive recovery, and how far we need to replay the WAL to reach a
  * consistent state.
  *
@@ -510,7 +508,7 @@ EnableStandbyMode(void)
  */
 void
 InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
-				bool *haveBackupLabel_ptr, bool *haveTblspcMap_ptr)
+				bool *haveTblspcMap_ptr)
 {
 	XLogPageReadPrivate *private;
 	struct stat st;
@@ -518,7 +516,7 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 	XLogRecord *record;
 	DBState		dbstate_at_startup;
 	bool		haveTblspcMap = false;
-	bool		haveBackupLabel = false;
+	bool		backupRecoveryRequired = false;
 	CheckPoint	checkPoint;
 	bool		backupFromStandby = false;
 
@@ -549,7 +547,7 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 
 	/*
 	 * Set the WAL reading processor now, as it will be needed when reading
-	 * the checkpoint record required (backup_label or not).
+	 * the checkpoint record required (backup recovery required or not).
 	 */
 	private = palloc0(sizeof(XLogPageReadPrivate));
 	xlogreader =
@@ -585,18 +583,34 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 	primary_image_masked = (char *) palloc(BLCKSZ);
 
 	/*
-	 * Read the backup_label file.  We want to run this part of the recovery
-	 * process after checking for signal files and after performing validation
-	 * of the recovery parameters.
+	 * Load recovery settings from pg_control.  We want to run this part of the
+	 * recovery process after checking for signal files and after performing
+	 * validation of the recovery parameters.
 	 */
-	if (read_backup_label(&CheckPointLoc, &CheckPointTLI, &backupEndRequired,
-						  &backupFromStandby))
+	if (ControlFile->backupRecoveryRequired)
 	{
 		List	   *tablespaces = NIL;
 
+		/* Initialize recovery from fields stored in pg_control */
+		CheckPointLoc = ControlFile->backupCheckPoint;
+		CheckPointTLI = ControlFile->backupStartPointTLI;
+		RedoStartLSN = ControlFile->backupStartPoint;
+		RedoStartTLI = ControlFile->backupStartPointTLI;
+		backupEndRequired = ControlFile->backupEndRequired;
+		backupFromStandby = ControlFile->backupFromStandby;
+
+		/* Clear fields used to initialize recovery */
+		ControlFile->backupCheckPoint = InvalidXLogRecPtr;
+		ControlFile->backupStartPointTLI = 0;
+		ControlFile->backupRecoveryRequired = false;
+		ControlFile->backupFromStandby = false;
+
+		/* Indicate that recovery was requested */
+		backupRecoveryRequired = true;
+
 		/*
-		 * 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 was requested, and thanks to the recovery
+		 * info, we know how far we need to replay to reach consistency. Enter
 		 * archive recovery directly.
 		 */
 		InArchiveRecovery = true;
@@ -604,8 +618,9 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 			EnableStandbyMode();
 
 		/*
-		 * When a backup_label file is present, we want to roll forward from
-		 * the checkpoint it identifies, rather than using pg_control.
+		 * When backup recovery is requested, we want to roll forward from
+		 * the checkpoint it identifies, rather than using the default
+		 * checkpoint.
 		 */
 		record = ReadCheckpointRecord(xlogprefetcher, CheckPointLoc,
 									  CheckPointTLI);
@@ -620,9 +635,8 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 
 			/*
 			 * Make sure that REDO location exists. This may not be the case
-			 * if there was a crash during an online backup, which left a
-			 * backup_label around that references a WAL segment that's
-			 * already been archived.
+			 * if recovery.signal is missing and the WAL has already been
+			 * archived.
 			 */
 			if (checkPoint.redo < CheckPointLoc)
 			{
@@ -631,20 +645,16 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 								checkPoint.ThisTimeLineID))
 					ereport(FATAL,
 							(errmsg("could not find redo location referenced by checkpoint record"),
-							 errhint("If you are restoring from a backup, touch \"%s/recovery.signal\" or \"%s/standby.signal\" and add required recovery options.\n"
-									 "If you are not restoring from a backup, try removing the file \"%s/backup_label\".\n"
-									 "Be careful: removing \"%s/backup_label\" will result in a corrupt cluster if restoring from a backup.",
-									 DataDir, DataDir, DataDir, DataDir)));
+							 errhint("If you are restoring from a backup, touch \"%s/recovery.signal\" or \"%s/standby.signal\" and add required recovery options.\n",
+									 DataDir, DataDir)));
 			}
 		}
 		else
 		{
 			ereport(FATAL,
 					(errmsg("could not locate required checkpoint record"),
-					 errhint("If you are restoring from a backup, touch \"%s/recovery.signal\" or \"%s/standby.signal\" and add required recovery options.\n"
-							 "If you are not restoring from a backup, try removing the file \"%s/backup_label\".\n"
-							 "Be careful: removing \"%s/backup_label\" will result in a corrupt cluster if restoring from a backup.",
-							 DataDir, DataDir, DataDir, DataDir)));
+					 errhint("If you are restoring from a backup, touch \"%s/recovery.signal\" or \"%s/standby.signal\" and add required recovery options.\n",
+							 DataDir, DataDir)));
 			wasShutdown = false;	/* keep compiler quiet */
 		}
 
@@ -679,37 +689,32 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 			/* tell the caller to delete it later */
 			haveTblspcMap = true;
 		}
-
-		/* tell the caller to delete it later */
-		haveBackupLabel = true;
 	}
 	else
 	{
-		/* No backup_label file has been found if we are here. */
-
 		/*
-		 * If tablespace_map file is present without backup_label file, there
-		 * is no use of such file.  There is no harm in retaining it, but it
-		 * is better to get rid of the map file so that we don't have any
+		 * If tablespace_map file is present without backup recovery requested,
+		 * there is no use of such file.  There is no harm in retaining it, but
+		 * it is better to get rid of the map file so that we don't have any
 		 * redundant file in data directory and it will avoid any sort of
 		 * confusion.  It seems prudent though to just rename the file out of
 		 * the way rather than delete it completely, also we ignore any error
 		 * that occurs in rename operation as even if map file is present
-		 * without backup_label file, it is harmless.
+		 * without backup recovery requested, it is harmless.
 		 */
 		if (stat(TABLESPACE_MAP, &st) == 0)
 		{
 			unlink(TABLESPACE_MAP_OLD);
 			if (durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, DEBUG1) == 0)
 				ereport(LOG,
-						(errmsg("ignoring file \"%s\" because no file \"%s\" exists",
-								TABLESPACE_MAP, BACKUP_LABEL_FILE),
+						(errmsg("ignoring file \"%s\" because backup recovery was not requested",
+								TABLESPACE_MAP),
 						 errdetail("File \"%s\" was renamed to \"%s\".",
 								   TABLESPACE_MAP, TABLESPACE_MAP_OLD)));
 			else
 				ereport(LOG,
-						(errmsg("ignoring file \"%s\" because no file \"%s\" exists",
-								TABLESPACE_MAP, BACKUP_LABEL_FILE),
+						(errmsg("ignoring file \"%s\" because backup recovery was not requested",
+								TABLESPACE_MAP),
 						 errdetail("Could not rename file \"%s\" to \"%s\": %m.",
 								   TABLESPACE_MAP, TABLESPACE_MAP_OLD)));
 		}
@@ -943,7 +948,7 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 		 * Any other state indicates that the backup somehow became corrupted
 		 * and we can't sensibly continue with recovery.
 		 */
-		if (haveBackupLabel)
+		if (backupRecoveryRequired)
 		{
 			ControlFile->backupStartPoint = checkPoint.redo;
 			ControlFile->backupEndRequired = backupEndRequired;
@@ -953,7 +958,7 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 				if (dbstate_at_startup != DB_IN_ARCHIVE_RECOVERY &&
 					dbstate_at_startup != DB_SHUTDOWNED_IN_RECOVERY)
 					ereport(FATAL,
-							(errmsg("backup_label contains data inconsistent with control file"),
+							(errmsg("pg_control contains inconsistent data for standby backup"),
 							 errhint("This means that the backup is corrupted and you will "
 									 "have to use another backup for recovery.")));
 				ControlFile->backupEndPoint = ControlFile->minRecoveryPoint;
@@ -983,7 +988,6 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 	missingContrecPtr = InvalidXLogRecPtr;
 
 	*wasShutdown_ptr = wasShutdown;
-	*haveBackupLabel_ptr = haveBackupLabel;
 	*haveTblspcMap_ptr = haveTblspcMap;
 }
 
@@ -1156,154 +1160,6 @@ validateRecoveryParameters(void)
 	}
 }
 
-/*
- * read_backup_label: check to see if a backup_label file is present
- *
- * If we see a backup_label during recovery, we assume that we are recovering
- * from a backup dump file, and we therefore roll forward from the checkpoint
- * identified by the label file, NOT what pg_control says.  This avoids the
- * problem that pg_control might have been archived one or more checkpoints
- * later than the start of the dump, and so if we rely on it as the start
- * point, we will fail to restore a consistent database state.
- *
- * Returns true if a backup_label was found (and fills the checkpoint
- * location and TLI into *checkPointLoc and *backupLabelTLI, respectively);
- * returns false if not. If this backup_label came from a streamed backup,
- * *backupEndRequired is set to true. If this backup_label was created during
- * recovery, *backupFromStandby is set to true.
- *
- * Also sets the global variables RedoStartLSN and RedoStartTLI with the LSN
- * and TLI read from the backup file.
- */
-static bool
-read_backup_label(XLogRecPtr *checkPointLoc, TimeLineID *backupLabelTLI,
-				  bool *backupEndRequired, bool *backupFromStandby)
-{
-	char		startxlogfilename[MAXFNAMELEN];
-	TimeLineID	tli_from_walseg,
-				tli_from_file;
-	FILE	   *lfp;
-	char		ch;
-	char		backuptype[20];
-	char		backupfrom[20];
-	char		backuplabel[MAXPGPATH];
-	char		backuptime[128];
-	uint32		hi,
-				lo;
-
-	/* suppress possible uninitialized-variable warnings */
-	*checkPointLoc = InvalidXLogRecPtr;
-	*backupLabelTLI = 0;
-	*backupEndRequired = false;
-	*backupFromStandby = false;
-
-	/*
-	 * See if label file is present
-	 */
-	lfp = AllocateFile(BACKUP_LABEL_FILE, "r");
-	if (!lfp)
-	{
-		if (errno != ENOENT)
-			ereport(FATAL,
-					(errcode_for_file_access(),
-					 errmsg("could not read file \"%s\": %m",
-							BACKUP_LABEL_FILE)));
-		return false;			/* it's not there, all is fine */
-	}
-
-	/*
-	 * Read and parse the START WAL LOCATION and CHECKPOINT lines (this code
-	 * is pretty crude, but we are not expecting any variability in the file
-	 * format).
-	 */
-	if (fscanf(lfp, "START WAL LOCATION: %X/%X (file %08X%16s)%c",
-			   &hi, &lo, &tli_from_walseg, startxlogfilename, &ch) != 5 || ch != '\n')
-		ereport(FATAL,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));
-	RedoStartLSN = ((uint64) hi) << 32 | lo;
-	RedoStartTLI = tli_from_walseg;
-	if (fscanf(lfp, "CHECKPOINT LOCATION: %X/%X%c",
-			   &hi, &lo, &ch) != 3 || ch != '\n')
-		ereport(FATAL,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));
-	*checkPointLoc = ((uint64) hi) << 32 | lo;
-	*backupLabelTLI = tli_from_walseg;
-
-	/*
-	 * BACKUP METHOD lets us know if this was a typical backup ("streamed",
-	 * which could mean either pg_basebackup or the pg_backup_start/stop
-	 * method was used) or if this label came from somewhere else (the only
-	 * other option today being from pg_rewind).  If this was a streamed
-	 * backup then we know that we need to play through until we get to the
-	 * end of the WAL which was generated during the backup (at which point we
-	 * will have reached consistency and backupEndRequired will be reset to be
-	 * false).
-	 */
-	if (fscanf(lfp, "BACKUP METHOD: %19s\n", backuptype) == 1)
-	{
-		if (strcmp(backuptype, "streamed") == 0)
-			*backupEndRequired = true;
-	}
-
-	/*
-	 * BACKUP FROM lets us know if this was from a primary or a standby.  If
-	 * it was from a standby, we'll double-check that the control file state
-	 * matches that of a standby.
-	 */
-	if (fscanf(lfp, "BACKUP FROM: %19s\n", backupfrom) == 1)
-	{
-		if (strcmp(backupfrom, "standby") == 0)
-			*backupFromStandby = true;
-	}
-
-	/*
-	 * Parse START TIME and LABEL. Those are not mandatory fields for recovery
-	 * but checking for their presence is useful for debugging and the next
-	 * sanity checks. Cope also with the fact that the result buffers have a
-	 * pre-allocated size, hence if the backup_label file has been generated
-	 * with strings longer than the maximum assumed here an incorrect parsing
-	 * happens. That's fine as only minor consistency checks are done
-	 * afterwards.
-	 */
-	if (fscanf(lfp, "START TIME: %127[^\n]\n", backuptime) == 1)
-		ereport(DEBUG1,
-				(errmsg_internal("backup time %s in file \"%s\"",
-								 backuptime, BACKUP_LABEL_FILE)));
-
-	if (fscanf(lfp, "LABEL: %1023[^\n]\n", backuplabel) == 1)
-		ereport(DEBUG1,
-				(errmsg_internal("backup label %s in file \"%s\"",
-								 backuplabel, BACKUP_LABEL_FILE)));
-
-	/*
-	 * START TIMELINE is new as of 11. Its parsing is not mandatory, still use
-	 * it as a sanity check if present.
-	 */
-	if (fscanf(lfp, "START TIMELINE: %u\n", &tli_from_file) == 1)
-	{
-		if (tli_from_walseg != tli_from_file)
-			ereport(FATAL,
-					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-					 errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE),
-					 errdetail("Timeline ID parsed is %u, but expected %u.",
-							   tli_from_file, tli_from_walseg)));
-
-		ereport(DEBUG1,
-				(errmsg_internal("backup timeline %u in file \"%s\"",
-								 tli_from_file, BACKUP_LABEL_FILE)));
-	}
-
-	if (ferror(lfp) || FreeFile(lfp))
-		ereport(FATAL,
-				(errcode_for_file_access(),
-				 errmsg("could not read file \"%s\": %m",
-						BACKUP_LABEL_FILE)));
-
-	return true;
-}
-
 /*
  * read_tablespace_map: check to see if a tablespace_map file is present
  *
diff --git a/src/backend/backup/basebackup.c b/src/backend/backup/basebackup.c
index f216b588422..a4bd79447fd 100644
--- a/src/backend/backup/basebackup.c
+++ b/src/backend/backup/basebackup.c
@@ -22,6 +22,7 @@
 #include "backup/basebackup.h"
 #include "backup/basebackup_sink.h"
 #include "backup/basebackup_target.h"
+#include "catalog/pg_control.h"
 #include "commands/defrem.h"
 #include "common/compression.h"
 #include "common/file_perm.h"
@@ -192,10 +193,9 @@ static const struct exclude_list_item excludeFiles[] =
 	{RELCACHE_INIT_FILENAME, true},
 
 	/*
-	 * backup_label and tablespace_map should not exist in a running cluster
-	 * capable of doing an online backup, but exclude them just in case.
+	 * tablespace_map should not exist in a running cluster capable of doing
+	 * an online backup, but exclude it just in case.
 	 */
-	{BACKUP_LABEL_FILE, false},
 	{TABLESPACE_MAP, false},
 
 	/*
@@ -325,19 +325,11 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 
 			if (ti->path == NULL)
 			{
-				struct stat statbuf;
 				bool		sendtblspclinks = true;
-				char	   *backup_label;
 
 				bbsink_begin_archive(sink, "base.tar");
 
-				/* In the main tar, include the backup_label first... */
-				backup_label = build_backup_content(backup_state, false);
-				sendFileWithContent(sink, BACKUP_LABEL_FILE,
-									backup_label, -1, &manifest);
-				pfree(backup_label);
-
-				/* Then the tablespace_map file, if required... */
+				/* Send the tablespace_map file, if required... */
 				if (opt->sendtblspcmapfile)
 				{
 					sendFileWithContent(sink, TABLESPACE_MAP,
@@ -349,14 +341,14 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 				sendDir(sink, ".", 1, false, state.tablespaces,
 						sendtblspclinks, &manifest, InvalidOid);
 
-				/* ... and pg_control after everything else. */
-				if (lstat(XLOG_CONTROL_FILE, &statbuf) != 0)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not stat file \"%s\": %m",
-									XLOG_CONTROL_FILE)));
-				sendFile(sink, XLOG_CONTROL_FILE, XLOG_CONTROL_FILE, &statbuf,
-						 false, InvalidOid, InvalidOid, &manifest);
+				/* End the backup before sending pg_control */
+				basebackup_progress_wait_wal_archive(&state);
+				do_pg_backup_stop(backup_state, !opt->nowait);
+
+				/* Send copy of pg_control containing recovery info */
+				sendFileWithContent(sink, XLOG_CONTROL_FILE,
+									(char *)backup_state->controlFile,
+									PG_CONTROL_MAX_SAFE_SIZE, &manifest);
 			}
 			else
 			{
@@ -390,9 +382,6 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 			}
 		}
 
-		basebackup_progress_wait_wal_archive(&state);
-		do_pg_backup_stop(backup_state, !opt->nowait);
-
 		endptr = backup_state->stoppoint;
 		endtli = backup_state->stoptli;
 
diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql
index 35d738d5763..24bf34b45eb 100644
--- a/src/backend/catalog/system_functions.sql
+++ b/src/backend/catalog/system_functions.sql
@@ -384,13 +384,15 @@ BEGIN ATOMIC
 END;
 
 CREATE OR REPLACE FUNCTION
-  pg_backup_start(label text, fast boolean DEFAULT false)
-  RETURNS pg_lsn STRICT VOLATILE LANGUAGE internal AS 'pg_backup_start'
+  pg_backup_start(label text, fast boolean DEFAULT false, OUT lsn pg_lsn,
+        OUT timeline_id int8, OUT start timestamptz)
+  RETURNS record STRICT VOLATILE LANGUAGE internal AS 'pg_backup_start'
   PARALLEL RESTRICTED;
 
 CREATE OR REPLACE FUNCTION pg_backup_stop (
-        wait_for_archive boolean DEFAULT true, OUT lsn pg_lsn,
-        OUT labelfile text, OUT spcmapfile text)
+        wait_for_archive boolean DEFAULT true, OUT pg_control_file bytea,
+        OUT tablespace_map_file text, OUT lsn pg_lsn, OUT timeline_id int8,
+        OUT stop timestamptz)
   RETURNS record STRICT VOLATILE LANGUAGE internal as 'pg_backup_stop'
   PARALLEL RESTRICTED;
 
diff --git a/src/bin/pg_basebackup/t/010_pg_basebackup.pl b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
index b9f5e1266b4..c655cb03352 100644
--- a/src/bin/pg_basebackup/t/010_pg_basebackup.pl
+++ b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
@@ -171,8 +171,8 @@ SKIP:
 
 # Write some files to test that they are not copied.
 foreach my $filename (
-	qw(backup_label tablespace_map postgresql.auto.conf.tmp
-	current_logfiles.tmp global/pg_internal.init.123))
+	qw(tablespace_map postgresql.auto.conf.tmp current_logfiles.tmp
+	   global/pg_internal.init.123))
 {
 	open my $file, '>>', "$pgdata/$filename";
 	print $file "DONOTCOPY";
@@ -261,14 +261,13 @@ foreach my $filename (@tempRelationFiles)
 		"base/$postgresOid/$filename not copied");
 }
 
-# Make sure existing backup_label was ignored.
-isnt(slurp_file("$tempdir/backup/backup_label"),
-	'DONOTCOPY', 'existing backup_label not copied');
+# Make sure existing tablespace_map was ignored.
+ok(!-f "$tempdir/backup/tablespace_map", 'tablespace_map not in backup');
 rmtree("$tempdir/backup");
 
-# Now delete the bogus backup_label file since it will interfere with startup
-unlink("$pgdata/backup_label")
-  or BAIL_OUT("unable to unlink $pgdata/backup_label");
+# Now delete the bogus tablespace_map file since it will interfere with startup
+unlink("$pgdata/tablespace_map")
+  or BAIL_OUT("unable to unlink $pgdata/tablespace_map");
 
 $node->command_ok(
 	[
diff --git a/src/bin/pg_controldata/pg_controldata.c b/src/bin/pg_controldata/pg_controldata.c
index 93e0837947c..cc515b622ff 100644
--- a/src/bin/pg_controldata/pg_controldata.c
+++ b/src/bin/pg_controldata/pg_controldata.c
@@ -277,10 +277,18 @@ main(int argc, char *argv[])
 		   LSN_FORMAT_ARGS(ControlFile->minRecoveryPoint));
 	printf(_("Min recovery ending loc's timeline:   %u\n"),
 		   ControlFile->minRecoveryPointTLI);
+	printf(_("Backup checkpoint location:           %X/%X\n"),
+		   LSN_FORMAT_ARGS(ControlFile->backupCheckPoint));
 	printf(_("Backup start location:                %X/%X\n"),
 		   LSN_FORMAT_ARGS(ControlFile->backupStartPoint));
+	printf(_("Backup start location's timeline:     %u\n"),
+		   ControlFile->backupStartPointTLI);
 	printf(_("Backup end location:                  %X/%X\n"),
 		   LSN_FORMAT_ARGS(ControlFile->backupEndPoint));
+	printf(_("Backup recovery required:        		%s\n"),
+		   ControlFile->backupRecoveryRequired ? _("yes") : _("no"));
+	printf(_("Backup from standby:        			%s\n"),
+		   ControlFile->backupFromStandby ? _("yes") : _("no"));
 	printf(_("End-of-backup record required:        %s\n"),
 		   ControlFile->backupEndRequired ? _("yes") : _("no"));
 	printf(_("wal_level setting:                    %s\n"),
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 3ae3fc06df2..255101ff3a1 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -870,8 +870,12 @@ RewriteControlFile(void)
 	ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
 	ControlFile.minRecoveryPoint = 0;
 	ControlFile.minRecoveryPointTLI = 0;
+	ControlFile.backupCheckPoint = 0;
 	ControlFile.backupStartPoint = 0;
+	ControlFile.backupStartPointTLI = 0;
 	ControlFile.backupEndPoint = 0;
+	ControlFile.backupRecoveryRequired = false;
+	ControlFile.backupFromStandby = false;
 	ControlFile.backupEndRequired = false;
 
 	/*
diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index ecadd69dc53..213f4e71b88 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -139,11 +139,10 @@ static const struct exclude_list_item excludeFiles[] =
 	{"pg_internal.init", true}, /* defined as RELCACHE_INIT_FILENAME */
 
 	/*
-	 * If there is a backup_label or tablespace_map file, it indicates that a
-	 * recovery failed and this cluster probably can't be rewound, but exclude
-	 * them anyway if they are found.
+	 * If there is a tablespace_map file, it indicates that a recovery failed
+	 * and this cluster probably can't be rewound, but exclude it anyway if it
+	 * is found.
 	 */
-	{"backup_label", false},	/* defined as BACKUP_LABEL_FILE */
 	{"tablespace_map", false},	/* defined as TABLESPACE_MAP */
 
 	/*
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index bfd44a284e2..f42782e2eab 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -39,9 +39,6 @@ static void perform_rewind(filemap_t *filemap, rewind_source *source,
 						   TimeLineID chkpttli,
 						   XLogRecPtr chkptredo);
 
-static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
-							  XLogRecPtr checkpointloc);
-
 static void digestControlFile(ControlFileData *ControlFile,
 							  const char *content, size_t size);
 static void getRestoreCommand(const char *argv0);
@@ -654,7 +651,7 @@ perform_rewind(filemap_t *filemap, rewind_source *source,
 		pg_log_info("creating backup label and updating control file");
 
 	/*
-	 * Create a backup label file, to tell the target where to begin the WAL
+	 * Get recovery fields to tell the target where to begin the WAL
 	 * replay. Normally, from the last common checkpoint between the source
 	 * and the target. But if the source is a standby server, it's possible
 	 * that the last common checkpoint is *after* the standby's restartpoint.
@@ -672,7 +669,6 @@ perform_rewind(filemap_t *filemap, rewind_source *source,
 		chkpttli = ControlFile_source.checkPointCopy.ThisTimeLineID;
 		chkptrec = ControlFile_source.checkPoint;
 	}
-	createBackupLabel(chkptredo, chkpttli, chkptrec);
 
 	/*
 	 * Update control file of target, to tell the target how far it must
@@ -722,6 +718,12 @@ perform_rewind(filemap_t *filemap, rewind_source *source,
 	ControlFile_new.minRecoveryPoint = endrec;
 	ControlFile_new.minRecoveryPointTLI = endtli;
 	ControlFile_new.state = DB_IN_ARCHIVE_RECOVERY;
+	ControlFile_new.backupRecoveryRequired = true;
+	ControlFile_new.backupFromStandby = true;
+	ControlFile_new.backupEndRequired = false;
+	ControlFile_new.backupCheckPoint = chkptrec;
+	ControlFile_new.backupStartPoint = chkptredo;
+	ControlFile_new.backupStartPointTLI = chkpttli;
 	if (!dry_run)
 		update_controlfile(datadir_target, &ControlFile_new, do_sync);
 }
@@ -729,7 +731,10 @@ perform_rewind(filemap_t *filemap, rewind_source *source,
 static void
 sanityChecks(void)
 {
-	/* TODO Check that there's no backup_label in either cluster */
+	/*
+	 * TODO Check that neither cluster has backupRecoveryRequested set in
+	 * pg_control.
+	 */
 
 	/* Check system_identifier match */
 	if (ControlFile_target.system_identifier != ControlFile_source.system_identifier)
@@ -951,51 +956,6 @@ findCommonAncestorTimeline(TimeLineHistoryEntry *a_history, int a_nentries,
 	}
 }
 
-
-/*
- * Create a backup_label file that forces recovery to begin at the last common
- * checkpoint.
- */
-static void
-createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli, XLogRecPtr checkpointloc)
-{
-	XLogSegNo	startsegno;
-	time_t		stamp_time;
-	char		strfbuf[128];
-	char		xlogfilename[MAXFNAMELEN];
-	struct tm  *tmp;
-	char		buf[1000];
-	int			len;
-
-	XLByteToSeg(startpoint, startsegno, WalSegSz);
-	XLogFileName(xlogfilename, starttli, startsegno, WalSegSz);
-
-	/*
-	 * Construct backup label file
-	 */
-	stamp_time = time(NULL);
-	tmp = localtime(&stamp_time);
-	strftime(strfbuf, sizeof(strfbuf), "%Y-%m-%d %H:%M:%S %Z", tmp);
-
-	len = snprintf(buf, sizeof(buf),
-				   "START WAL LOCATION: %X/%X (file %s)\n"
-				   "CHECKPOINT LOCATION: %X/%X\n"
-				   "BACKUP METHOD: pg_rewind\n"
-				   "BACKUP FROM: standby\n"
-				   "START TIME: %s\n",
-	/* omit LABEL: line */
-				   LSN_FORMAT_ARGS(startpoint), xlogfilename,
-				   LSN_FORMAT_ARGS(checkpointloc),
-				   strfbuf);
-	if (len >= sizeof(buf))
-		pg_fatal("backup label buffer too small");	/* shouldn't happen */
-
-	/* TODO: move old file out of the way, if any. */
-	open_target_file("backup_label", true); /* BACKUP_LABEL_FILE */
-	write_target_range(buf, 0, len);
-	close_target_file();
-}
-
 /*
  * Check CRC of control file
  */
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index a14126d164f..3aac6839a70 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -293,8 +293,6 @@ extern SessionBackupState get_backup_status(void);
 /* File path names (all relative to $PGDATA) */
 #define RECOVERY_SIGNAL_FILE	"recovery.signal"
 #define STANDBY_SIGNAL_FILE		"standby.signal"
-#define BACKUP_LABEL_FILE		"backup_label"
-#define BACKUP_LABEL_OLD		"backup_label.old"
 
 #define TABLESPACE_MAP			"tablespace_map"
 #define TABLESPACE_MAP_OLD		"tablespace_map.old"
diff --git a/src/include/access/xlogbackup.h b/src/include/access/xlogbackup.h
index 1611358137b..f2c3672fed6 100644
--- a/src/include/access/xlogbackup.h
+++ b/src/include/access/xlogbackup.h
@@ -15,6 +15,7 @@
 #define XLOG_BACKUP_H
 
 #include "access/xlogdefs.h"
+#include "catalog/pg_control.h"
 #include "pgtime.h"
 
 /* Structure to hold backup state. */
@@ -33,9 +34,18 @@ typedef struct BackupState
 	XLogRecPtr	stoppoint;		/* backup stop WAL location */
 	TimeLineID	stoptli;		/* backup stop TLI */
 	pg_time_t	stoptime;		/* backup stop time */
+
+	/*
+	 * After pg_backup_stop() returns this field will contain a copy of
+	 * pg_control that should be stored with the backup. Fields have been
+	 * updated for recovery and the CRC has been recalculated. The buffer
+	 * is padded to PG_CONTROL_MAX_SAFE_SIZE so that pg_control is always
+	 * a consistent size but smaller (and hopefully easier to handle) than
+	 * PG_CONTROL_FILE_SIZE. Bytes after sizeof(ControlFileData) are zeroed.
+	 */
+	uint8_t controlFile[PG_CONTROL_MAX_SAFE_SIZE];
 } BackupState;
 
-extern char *build_backup_content(BackupState *state,
-								  bool ishistoryfile);
+extern char *build_backup_history_content(BackupState *state);
 
 #endif							/* XLOG_BACKUP_H */
diff --git a/src/include/access/xlogrecovery.h b/src/include/access/xlogrecovery.h
index ee0bc742782..981266f7340 100644
--- a/src/include/access/xlogrecovery.h
+++ b/src/include/access/xlogrecovery.h
@@ -80,8 +80,7 @@ extern Size XLogRecoveryShmemSize(void);
 extern void XLogRecoveryShmemInit(void);
 
 extern void InitWalRecovery(ControlFileData *ControlFile,
-							bool *wasShutdown_ptr, bool *haveBackupLabel_ptr,
-							bool *haveTblspcMap_ptr);
+							bool *wasShutdown_ptr, bool *haveTblspcMap_ptr);
 extern void PerformWalRecovery(void);
 
 /*
diff --git a/src/include/catalog/pg_control.h b/src/include/catalog/pg_control.h
index 2ae72e3b266..8144c972ec1 100644
--- a/src/include/catalog/pg_control.h
+++ b/src/include/catalog/pg_control.h
@@ -146,6 +146,9 @@ typedef struct ControlFileData
 	 * to disk, we mustn't start up until we reach X again. Zero when not
 	 * doing archive recovery.
 	 *
+	 * backupCheckPoint is the backup start checkpoint and is set to zero after
+	 * recovery is initialized.
+	 *
 	 * backupStartPoint is the redo pointer of the backup start checkpoint, if
 	 * we are recovering from an online backup and haven't reached the end of
 	 * backup yet. It is reset to zero when the end of backup is reached, and
@@ -160,14 +163,27 @@ typedef struct ControlFileData
 	 * pg_control which was backed up last. It is reset to zero when the end
 	 * of backup is reached, and we mustn't start up before that.
 	 *
+	 * backupRecoveryRequired indicates that the pg_control file was provided
+	 * by a backup or pg_rewind and recovery settings need to be copied. It will
+	 * be set to false when the settings have been copied.
+	 *
+	 * backupFromStandby indicates that the backup was taken on a standby. It is
+	 * required to initialize recovery and set to false afterwards.
+	 *
 	 * If backupEndRequired is true, we know for sure that we're restoring
 	 * from a backup, and must see a backup-end record before we can safely
-	 * start up.
+	 * start up. Currently backupEndRequired should only be false if recovery
+	 * settings were configured by pg_rewind, which does not require an end
+	 * point.
 	 */
 	XLogRecPtr	minRecoveryPoint;
 	TimeLineID	minRecoveryPointTLI;
+	XLogRecPtr	backupCheckPoint;
 	XLogRecPtr	backupStartPoint;
 	XLogRecPtr	backupEndPoint;
+	TimeLineID	backupStartPointTLI;
+	bool 		backupRecoveryRequired;
+	bool 		backupFromStandby;
 	bool		backupEndRequired;
 
 	/*
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index f14aed422a7..cc8156c57e7 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6413,13 +6413,17 @@
   prosrc => 'pg_terminate_backend' },
 { oid => '2172', descr => 'prepare for taking an online backup',
   proname => 'pg_backup_start', provolatile => 'v', proparallel => 'r',
-  prorettype => 'pg_lsn', proargtypes => 'text bool',
+  prorettype => 'record', proargtypes => 'text bool',
+  proallargtypes => '{text,bool,pg_lsn,int8,timestamptz}',
+  proargmodes => '{i,i,o,o,o}',
+  proargnames => '{label,fast,lsn,timeline_id,start}',
   prosrc => 'pg_backup_start' },
 { oid => '2739', descr => 'finish taking an online backup',
   proname => 'pg_backup_stop', provolatile => 'v', proparallel => 'r',
   prorettype => 'record', proargtypes => 'bool',
-  proallargtypes => '{bool,pg_lsn,text,text}', proargmodes => '{i,o,o,o}',
-  proargnames => '{wait_for_archive,lsn,labelfile,spcmapfile}',
+  proallargtypes => '{bool,bytea,text,pg_lsn,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o}',
+  proargnames => '{wait_for_archive,pg_control_file,tablespace_map_file,lsn,timeline_id,stop}',
   prosrc => 'pg_backup_stop' },
 { oid => '3436', descr => 'promote standby server',
   proname => 'pg_promote', provolatile => 'v', prorettype => 'bool',
-- 
2.34.1

---

From: Michael Paquier <[email-masked]>
Date: Mon, 13 Nov 2023 13:36:56 +0900

> OK, hopefully it was just a blip.

Still nothing on this side.  So that seems really like a random blip
in the matrix.

> This has been split out.

Thanks, applied 0001.

> recovery field" vs "recovery from backup field".

Not sure.  I've never used this term when referring to recovery from a
backup.  Perhaps I'm just not used to it, still that sounds a bit
confusing here.

> consistent and before logons are allowed. Viewing them with pg_controldata
> makes sense, but I'm not sure pg_control_recovery() does.
> 
> end_of_backup_record_required ever non-zero when logged onto Postgres? Maybe
> I'm missing something?

Yeah, but custom backup/restore tools may want manipulate the contents
of the control file for their own work, so at least for the sake of
visibility it sounds important to me to show all the information at
hand, and that there is no need to.

-    The backup label

As a side note, it is a bit disappointing that we lose the backup
label from the backup itself, even if the patch changes correctly the
documentation to reflect the new behavior.  It is in the backup
history file on the node from where the base backup has been taken or
in the archives, hopefully.  However there is nothing that remains in
the base backup itself, and backups can be self-contained (easy with
pg_basebackup --wal-method=stream).  I think that we should retain a
minimum amount of information as a replacement for the backup_label,
at least.  With this state, the current patch slightly reduces the
debuggability of deployments.  That could be annoying for some users.

> New patches attached based on eb81e8e790.

Diving into the code for references about the backup label file, I
have spotted this log in pg_rewind that is now incorrect:
    if (showprogress)
        pg_log_info("creating backup label and updating control file");

Perhaps these two should be reversed to match with the header file.

+    /*

I don't mind the addition of a control file with the max safe size,
because it will never be higher than that.  However:

It seems to me that the base backup protocol should always send an 8k
file for the control file so as we maintain consistency with the
on-disk format.  Currently, a base backup taken with this patch
results in a control file of size 512B.

Similar comment for the control file returned by pg_backup_stop(),
which could just be made a 8k field?

And perhaps emphasize that this file should be an 8kB file in the
paragraph mentioning the data returned by pg_backup_stop()?

pg_control is mentioned twice, so perhaps this could be worded better?

PG_CONTROL_VERSION is important to not forget about..  Perhaps this
should be noted somewhere, or just changed in the patch itself.
Contrary to catalog changes, we do few of these in the control file so
there is close to zero risk of conflicts with other patches in the CF
app.
--
Michael

---

From: Michael Paquier <[email-masked]>
Date: Mon, 20 Nov 2023 10:15:49 +0900

(I am not exactly sure how, but we've lost pgsql-hackers on the way
when you sent v5.  Now added back in CC with the two latest patches
you've proposed attached.)

Here is a short summary of what has been missed by the lists:
- I've commented that the patch should not create, not show up in
fields returned the SQL functions or stream control files with a size
of 512B, just stick to 8kB.  If this is worth changing this should be
applied consistently across the board including initdb, discussed on
its own thread.
- The backup-related fields in the control file are reset at the end
of recovery.  I've suggested to not do that to keep a trace of what
was happening during recovery.  The latest version of the patch resets
the fields.
- With the backup_label file gone, we lose some information in the
backups themselves, which is not good.  Instead, you have suggested an
approach where this data is added to the backup manifest, meaning that
no information would be lost, particularly useful for self-contained
backups.  The fields planned to be added to the backup manifest are:
-- The start and end time of the backup, the end timestamp being
useful to know when stop time can be used for PITR.
-- The backup label.
I've agreed that it may be the best thing to do at this end to not
lose any data related to the removal of the backup_label file.

On Sun, Nov 19, 2023 at 02:14:32PM -0400, David Steele wrote:
> On 11/15/23 20:03, Michael Paquier wrote:
>> As the label is only an informational field, the parsing added to
>> pg_verifybackup is not really needed because it is used nowhere in the
>> validation process, so keeping the logic simpler would be the way to
>> go IMO.  This is contrary to the WAL range for example, where start
>> and end LSNs are used for validation with a pg_waldump command.
>> Robert, any comments about the addition of the label in the manifest?
>
> I'm sure Robert will comment on this when he gets the time, but for now I
> have backed off on passing the new info to pg_verifybackup and added
> start/stop time.

FWIW, I'm OK with the bits for the backup manifest as presented.  So
if there are no remarks and/or no objections, I'd like to apply it but
let give some room to others to comment on that as there's been a gap
in the emails exchanged on pgsql-hackers.  I hope that the summary
I've posted above covers everything.  So let's see about doing
something around the middle of next week.  With Thanksgiving in the
US, a lot of folks will not have the time to monitor what's happening
on this thread.

+      The end time for the backup. This is when the backup was stopped in
+      <productname>PostgreSQL</productname> and represents the earliest time
+      that can be used for time-based Point-In-Time Recovery.

This one is actually a very good point.  We'd lost this capacity with
the backup_label file gone without the end timestamps in the control
file.

> New patches attached based on b218fbb7.

I've noticed on the other thread the remark about being less
aggressive with the fields related to recovery in the control file, so
I assume that this patch should leave the fields be after the end of
recovery from the start and only rely on backupRecoveryRequired to
decide if the recovery should use the fields or not:
https://www.postgresql.org/message-id/241ccde1-1928-4ba2-a0bb-5350f7b191a8@=pgmasters.net

+	ControlFile->backupCheckPoint = InvalidXLogRecPtr;
 	ControlFile->backupStartPoint = InvalidXLogRecPtr;
+	ControlFile->backupStartPointTLI = 0;
 	ControlFile->backupEndPoint = InvalidXLogRecPtr;
+	ControlFile->backupFromStandby = false;
 	ControlFile->backupEndRequired = false;

Still, I get the temptation of being consistent with the current style
on HEAD to reset everything, as well.. 
--
Michael
From 97bb113b5bf5427449b748c3ee25b647a2c5fef5 Mon Sep 17 00:00:00 2001
From: David Steele <[email-masked]>
Date: Sun, 19 Nov 2023 16:54:36 +0000
Subject: Add label and start/stop time to backup manifest.

Add label passed by the user to pg_basebackup and backup start/stop time to
the backup_manifest file. Currently these fields are purely for informational
purposes.
---
 doc/src/sgml/backup-manifest.sgml        | 51 +++++++++++++++++++++
 src/backend/backup/backup_manifest.c     | 56 +++++++++++++++++++++++-
 src/backend/backup/basebackup.c          |  9 +++-
 src/bin/pg_verifybackup/parse_manifest.c | 40 +++++++++++++++++
 src/include/backup/backup_manifest.h     |  5 ++-
 5 files changed, 157 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/backup-manifest.sgml b/doc/src/sgml/backup-manifest.sgml
index 771be1310a..a80b79e587 100644
--- a/doc/src/sgml/backup-manifest.sgml
+++ b/doc/src/sgml/backup-manifest.sgml
@@ -42,6 +42,16 @@
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>Backup-Label</literal></term>
+    <listitem>
+     <para>
+      Backup label specified by the user. This will be set to a default value
+      if no backup label was specified.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>Files</literal></term>
     <listitem>
@@ -67,6 +77,17 @@
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>Time-Range</literal></term>
+    <listitem>
+     <para>
+      The associated value is always an object describing the start/stop time
+      of the backup. The structure of this object is further described in
+      <xref linkend="backup-manifest-time-range" />.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>Manifest-Checksum</literal></term>
     <listitem>
@@ -213,4 +234,34 @@
    for the same timeline.
   </para>
  </sect1>
+
+ <sect1 id="backup-manifest-time-range">
+  <title>Backup Manifest Time Range Object</title>
+
+  <para>
+   The object which describes the time range always has three keys:
+  </para>
+
+  <variablelist>
+   <varlistentry>
+    <term><literal>Start-Time</literal></term>
+    <listitem>
+     <para>
+      The start time for the backup.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>End-Time</literal></term>
+    <listitem>
+     <para>
+      The end time for the backup. This is when the backup was stopped in
+      <productname>PostgreSQL</productname> and represents the earliest time
+      that can be used for time-based Point-In-Time Recovery.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </sect1>
 </chapter>
diff --git a/src/backend/backup/backup_manifest.c b/src/backend/backup/backup_manifest.c
index aeed362a9a..9540f05964 100644
--- a/src/backend/backup/backup_manifest.c
+++ b/src/backend/backup/backup_manifest.c
@@ -56,7 +56,8 @@ IsManifestEnabled(backup_manifest_info *manifest)
 void
 InitializeBackupManifest(backup_manifest_info *manifest,
 						 backup_manifest_option want_manifest,
-						 pg_checksum_type manifest_checksum_type)
+						 pg_checksum_type manifest_checksum_type,
+						 const char *label)
 {
 	memset(manifest, 0, sizeof(backup_manifest_info));
 	manifest->checksum_type = manifest_checksum_type;
@@ -78,9 +79,21 @@ InitializeBackupManifest(backup_manifest_info *manifest,
 	manifest->still_checksumming = true;
 
 	if (want_manifest != MANIFEST_OPTION_NO)
+	{
+		StringInfoData buf;
+
 		AppendToManifest(manifest,
 						 "{ \"PostgreSQL-Backup-Manifest-Version\": 1,\n"
-						 "\"Files\": [");
+						 "\"Backup-Label\": ");
+
+		/* JSON encode label and add it to manifest */
+		initStringInfo(&buf);
+		escape_json(&buf, label);
+		AppendStringToManifest(manifest, buf.data);
+		pfree(buf.data);
+
+		AppendToManifest(manifest, ",\n\"Files\": [");
+	}
 }
 
 /*
@@ -308,6 +321,45 @@ AddWALInfoToBackupManifest(backup_manifest_info *manifest, XLogRecPtr startptr,
 	AppendStringToManifest(manifest, "\n],\n");
 }
 
+/*
+ * Add backup start/end time information to the manifest.
+ */
+void
+AddTimeInfoToBackupManifest(backup_manifest_info *manifest, pg_time_t starttime,
+							pg_time_t endtime)
+{
+	StringInfoData buf;
+
+	if (!IsManifestEnabled(manifest))
+		return;
+
+	/* Start the time range. */
+	AppendStringToManifest(manifest, "\"Time-Range\": { ");
+
+	/*
+	 * Convert start/end time to strings and append them to the manifest. Since
+	 * it's not clear what time zone to use and since time zone definitions can
+	 * change, possibly causing confusion, use GMT always.
+	 */
+	initStringInfo(&buf);
+
+	appendStringInfoString(&buf, "\"Start-Time\": \"");
+	enlargeStringInfo(&buf, 128);
+	buf.len += pg_strftime(&buf.data[buf.len], 128, "%Y-%m-%d %H:%M:%S %Z",
+						   pg_gmtime(&starttime));
+	appendStringInfoString(&buf, "\", \"End-Time\": \"");
+	enlargeStringInfo(&buf, 128);
+	buf.len += pg_strftime(&buf.data[buf.len], 128, "%Y-%m-%d %H:%M:%S %Z",
+						   pg_gmtime(&endtime));
+	appendStringInfoString(&buf, "\" },\n");
+
+	/* Add to the manifest. */
+	AppendStringToManifest(manifest, buf.data);
+
+	/* Avoid leaking memory. */
+	pfree(buf.data);
+}
+
 /*
  * Finalize the backup manifest, and send it to the client.
  */
diff --git a/src/backend/backup/basebackup.c b/src/backend/backup/basebackup.c
index 35dd79babc..c7b3ba3e6e 100644
--- a/src/backend/backup/basebackup.c
+++ b/src/backend/backup/basebackup.c
@@ -225,6 +225,8 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 	bbsink_state state;
 	XLogRecPtr	endptr;
 	TimeLineID	endtli;
+	pg_time_t	starttime;
+	pg_time_t	stoptime;
 	backup_manifest_info manifest;
 	BackupState *backup_state;
 	StringInfo	tablespace_map;
@@ -243,7 +245,7 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 	backup_started_in_recovery = RecoveryInProgress();
 
 	InitializeBackupManifest(&manifest, opt->manifest,
-							 opt->manifest_checksum_type);
+							 opt->manifest_checksum_type, opt->label);
 
 	total_checksum_failures = 0;
 
@@ -380,6 +382,10 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 		endptr = backup_state->stoppoint;
 		endtli = backup_state->stoptli;
 
+		/* Record start/stop time for manifest */
+		starttime = backup_state->starttime;
+		stoptime = backup_state->stoptime;
+
 		/* Deallocate backup-related variables. */
 		pfree(tablespace_map->data);
 		pfree(tablespace_map);
@@ -629,6 +635,7 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 
 	AddWALInfoToBackupManifest(&manifest, state.startptr, state.starttli,
 							   endptr, endtli);
+	AddTimeInfoToBackupManifest(&manifest, starttime, stoptime);
 
 	SendBackupManifest(&manifest, sink);
 
diff --git a/src/bin/pg_verifybackup/parse_manifest.c b/src/bin/pg_verifybackup/parse_manifest.c
index bf0227c668..408af88e58 100644
--- a/src/bin/pg_verifybackup/parse_manifest.c
+++ b/src/bin/pg_verifybackup/parse_manifest.c
@@ -25,6 +25,7 @@ typedef enum
 	JM_EXPECT_TOPLEVEL_END,
 	JM_EXPECT_TOPLEVEL_FIELD,
 	JM_EXPECT_VERSION_VALUE,
+	JM_EXPECT_BACKUP_LABEL_VALUE,
 	JM_EXPECT_FILES_START,
 	JM_EXPECT_FILES_NEXT,
 	JM_EXPECT_THIS_FILE_FIELD,
@@ -33,6 +34,9 @@ typedef enum
 	JM_EXPECT_WAL_RANGES_NEXT,
 	JM_EXPECT_THIS_WAL_RANGE_FIELD,
 	JM_EXPECT_THIS_WAL_RANGE_VALUE,
+	JM_EXPECT_TIME_RANGE_START,
+	JM_EXPECT_THIS_TIME_RANGE_FIELD,
+	JM_EXPECT_THIS_TIME_RANGE_VALUE,
 	JM_EXPECT_MANIFEST_CHECKSUM_VALUE,
 	JM_EXPECT_EOF,
 } JsonManifestSemanticState;
@@ -188,6 +192,9 @@ json_manifest_object_start(void *state)
 			parse->start_lsn = NULL;
 			parse->end_lsn = NULL;
 			break;
+		case JM_EXPECT_TIME_RANGE_START:
+			parse->state = JM_EXPECT_THIS_TIME_RANGE_FIELD;
+			break;
 		default:
 			json_manifest_parse_failure(parse->context,
 										"unexpected object start");
@@ -223,6 +230,9 @@ json_manifest_object_end(void *state)
 			json_manifest_finalize_wal_range(parse);
 			parse->state = JM_EXPECT_WAL_RANGES_NEXT;
 			break;
+		case JM_EXPECT_THIS_TIME_RANGE_FIELD:
+			parse->state = JM_EXPECT_TOPLEVEL_FIELD;
+			break;
 		default:
 			json_manifest_parse_failure(parse->context,
 										"unexpected object end");
@@ -312,6 +322,13 @@ json_manifest_object_field_start(void *state, char *fname, bool isnull)
 				break;
 			}
 
+			/* Is this the backup label? */
+			if (strcmp(fname, "Backup-Label") == 0)
+			{
+				parse->state = JM_EXPECT_BACKUP_LABEL_VALUE;
+				break;
+			}
+
 			/* Is this the list of files? */
 			if (strcmp(fname, "Files") == 0)
 			{
@@ -326,6 +343,13 @@ json_manifest_object_field_start(void *state, char *fname, bool isnull)
 				break;
 			}
 
+			/* Is this the time range? */
+			if (strcmp(fname, "Time-Range") == 0)
+			{
+				parse->state = JM_EXPECT_TIME_RANGE_START;
+				break;
+			}
+
 			/* Is this the manifest checksum? */
 			if (strcmp(fname, "Manifest-Checksum") == 0)
 			{
@@ -372,6 +396,14 @@ json_manifest_object_field_start(void *state, char *fname, bool isnull)
 			parse->state = JM_EXPECT_THIS_WAL_RANGE_VALUE;
 			break;
 
+		case JM_EXPECT_THIS_TIME_RANGE_FIELD:
+			if (strcmp(fname, "Start-Time") != 0 &&
+				strcmp(fname, "End-Time") != 0)
+				json_manifest_parse_failure(parse->context,
+											"unexpected time range field");
+			parse->state = JM_EXPECT_THIS_TIME_RANGE_VALUE;
+			break;
+
 		default:
 			json_manifest_parse_failure(parse->context,
 										"unexpected object field");
@@ -410,6 +442,10 @@ json_manifest_scalar(void *state, char *token, JsonTokenType tokentype)
 			parse->state = JM_EXPECT_TOPLEVEL_FIELD;
 			break;
 
+		case JM_EXPECT_BACKUP_LABEL_VALUE:
+			parse->state = JM_EXPECT_TOPLEVEL_FIELD;
+			break;
+
 		case JM_EXPECT_THIS_FILE_VALUE:
 			switch (parse->file_field)
 			{
@@ -451,6 +487,10 @@ json_manifest_scalar(void *state, char *token, JsonTokenType tokentype)
 			parse->state = JM_EXPECT_THIS_WAL_RANGE_FIELD;
 			break;
 
+		case JM_EXPECT_THIS_TIME_RANGE_VALUE:
+			parse->state = JM_EXPECT_THIS_TIME_RANGE_FIELD;
+			break;
+
 		case JM_EXPECT_MANIFEST_CHECKSUM_VALUE:
 			parse->state = JM_EXPECT_TOPLEVEL_END;
 			parse->manifest_checksum = token;
diff --git a/src/include/backup/backup_manifest.h b/src/include/backup/backup_manifest.h
index bd7067ae42..4ab1291bba 100644
--- a/src/include/backup/backup_manifest.h
+++ b/src/include/backup/backup_manifest.h
@@ -37,7 +37,8 @@ typedef struct backup_manifest_info
 
 extern void InitializeBackupManifest(backup_manifest_info *manifest,
 									 backup_manifest_option want_manifest,
-									 pg_checksum_type manifest_checksum_type);
+									 pg_checksum_type manifest_checksum_type,
+									 const char *label);
 extern void AddFileToBackupManifest(backup_manifest_info *manifest,
 									Oid spcoid,
 									const char *pathname, size_t size,
@@ -47,6 +48,8 @@ extern void AddWALInfoToBackupManifest(backup_manifest_info *manifest,
 									   XLogRecPtr startptr,
 									   TimeLineID starttli, XLogRecPtr endptr,
 									   TimeLineID endtli);
+extern void AddTimeInfoToBackupManifest(backup_manifest_info *manifest,
+										pg_time_t starttime, pg_time_t endtime);
 
 extern void SendBackupManifest(backup_manifest_info *manifest, bbsink *sink);
 extern void FreeBackupManifest(backup_manifest_info *manifest);
-- 
2.34.1

From 6b732c6e085a4ef2ec717af943b44d02cb4b9849 Mon Sep 17 00:00:00 2001
From: David Steele <[email-masked]>
Date: Sun, 19 Nov 2023 16:54:37 +0000
Subject: Add recovery to pg_control and remove backup_label.

Simplify and harden recovery by removing backup_label and storing recovery
information directly in pg_control. Instead of backup software copying
pg_control from PGDATA, it stores an updated version that is returned from
pg_backup_stop(). This is better for the following reasons:

* The user can no longer remove backup_label and get what looks like a
successful recovery (while almost certainly causing corruption). If pg_control
is removed the cluster will not start. The user may try pg_resetwal, but that
tool makes it pretty clear that corruption will result from its use. We could
also modify pg_resetwal to complain if recovery info is present in pg_control.

* We don't need to worry about backup software seeing a torn copy of pg_control,
since Postgres can safely read it out of memory and provide a valid copy via
pg_backup_stop(). This solves torn reads without needing to write pg_control via
a temp file, which may affect performance on a standby.

Since backup_label is now gone, the fields that used to be in backup_label are
now provided as columns returned from pg_backup_start() and pg_backup_stop() and
the backup history file is still written to the archive. For pg_basebackup, the
label passed on the cmd line as --label is now stored in the manifest.

Control and catalog version bumps are required.
---
 doc/src/sgml/backup.sgml                     |  31 ++-
 doc/src/sgml/func.sgml                       |  41 ++-
 doc/src/sgml/ref/pg_rewind.sgml              |   6 +-
 src/backend/access/transam/xlog.c            |  67 ++---
 src/backend/access/transam/xlogbackup.c      |  39 ++-
 src/backend/access/transam/xlogfuncs.c       |  50 ++--
 src/backend/access/transam/xlogrecovery.c    | 249 ++++---------------
 src/backend/backup/basebackup.c              |  37 +--
 src/backend/catalog/system_functions.sql     |  10 +-
 src/backend/utils/misc/pg_controldata.c      |  22 +-
 src/bin/pg_basebackup/t/010_pg_basebackup.pl |  15 +-
 src/bin/pg_controldata/pg_controldata.c      |   8 +
 src/bin/pg_resetwal/pg_resetwal.c            |   4 +
 src/bin/pg_rewind/filemap.c                  |   7 +-
 src/bin/pg_rewind/pg_rewind.c                |  64 +----
 src/include/access/xlog.h                    |   2 -
 src/include/access/xlogbackup.h              |  12 +-
 src/include/access/xlogrecovery.h            |   3 +-
 src/include/catalog/pg_control.h             |  19 +-
 src/include/catalog/pg_proc.dat              |  16 +-
 20 files changed, 293 insertions(+), 409 deletions(-)

index 8cb24d6ae5..584384875b 100644
 
    <para>
 
    <para>
-    The backup label
index 93f068edcf..5f27cce161 100644
@@ -26865,7 +26865,10 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
@@ -26877,6 +26880,13 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
@@ -26892,13 +26902,15 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
@@ -26930,13 +26942,18 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
+        of the backup and are required as part of the restore process. Note that
+        <filename>pg_control</filename> will be 8192KiB to match the on-disk
+        size of <filename>pg_control</filename>. The remainder of the columns
+        contain information about the end of the backup and can be ignored: the
+        <parameter>lsn</parameter> column holds the ending write-ahead log
+        location, the <parameter>timeline_id</parameter> column holds the ending
+        timeline, and the <parameter>stop</parameter> column holds the ending
+        timestamp.
index 8e0000d39f..404ce7c65e 100644
@@ -410,9 +409,8 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
-      the checkpoint created at failover and configure the
-      <filename>pg_control</filename> file with a minimum consistency LSN
+      the checkpoint created at failover and with a minimum consistency LSN
       when rewinding from a live source or the last checkpoint LSN when
       rewinding from a stopped source.
index 1159dff1a6..928cad0651 100644

-		/*
@@ -5951,8 +5936,11 @@ ReachedEndOfBackup(XLogRecPtr EndRecPtr, TimeLineID tli)
 		ControlFile->minRecoveryPointTLI = tli;
 	}
 
+	ControlFile->backupCheckPoint = InvalidXLogRecPtr;
 	ControlFile->backupStartPoint = InvalidXLogRecPtr;
+	ControlFile->backupStartPointTLI = 0;
 	ControlFile->backupEndPoint = InvalidXLogRecPtr;
+	ControlFile->backupFromStandby = false;
 	ControlFile->backupEndRequired = false;
 	UpdateControlFile();
 
@@ -8744,11 +8732,33 @@ do_pg_backup_stop(BackupState *state, bool waitforarchive)
 	int			seconds_before_warning;
 	int			waits = 0;
 	bool		reported_waiting = false;
+	ControlFileData *controlFileCopy = (ControlFileData *)state->controlFile;
 
 	Assert(state != NULL);

+	/*
+	memset(controlFileCopy, 0, PG_CONTROL_FILE_SIZE);
@@ -8850,11 +8860,8 @@ do_pg_backup_stop(BackupState *state, bool waitforarchive)
 
-
@@ -8896,7 +8903,7 @@ do_pg_backup_stop(BackupState *state, bool waitforarchive)
 							histfilepath)));

index 21d68133ae..22c95f3c4c 100644
 
 /*

-	if (ishistoryfile)
-	{

-	if (ishistoryfile)
-	{
-		char		stopstrfbuf[128];
-

 	data = result->data;
 	pfree(result);
index 45a70668b1..d81d36705f 100644

 

 
-	/* Build the contents of backup_label */
-	backup_label = build_backup_content(backup_state, false);
-
-	values[0] = LSNGetDatum(backup_state->stoppoint);
-	values[1] = CStringGetTextDatum(backup_label);
-	values[2] = CStringGetTextDatum(tablespace_map->data);
+	/* Build the contents of pg_control */
+	pg_control_bytea = (bytea *) palloc(PG_CONTROL_FILE_SIZE + VARHDRSZ);
+	SET_VARSIZE(pg_control_bytea, PG_CONTROL_FILE_SIZE + VARHDRSZ);
+	memcpy(VARDATA(pg_control_bytea), backup_state->controlFile, PG_CONTROL_FILE_SIZE);

index c61566666a..d05ff41f60 100644
 
 /*

 
 	/*
@@ -585,18 +583,33 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 
 	/*
 
+		/* Initialize recovery from fields stored in pg_control */
+		CheckPointLoc = ControlFile->backupCheckPoint;
+		CheckPointTLI = ControlFile->backupStartPointTLI;
+		RedoStartLSN = ControlFile->backupStartPoint;
+		RedoStartTLI = ControlFile->backupStartPointTLI;
+		backupEndRequired = ControlFile->backupEndRequired;
+		backupFromStandby = ControlFile->backupFromStandby;
+
+		/*
+		* Clear backupRecoveryRequired in ControlFile so we do not initialize
+		* recovery settings again, but also set a local variable so later logic
+		* knows that backup recovery was initialized.
+		*/
+		ControlFile->backupRecoveryRequired = false;
+		backupRecoveryRequired = true;
+
 		/*
-		 * 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 was requested, and thanks to the recovery
+		 * info, we know how far we need to replay to reach consistency. Enter
 		 * archive recovery directly.
 		 */
 		InArchiveRecovery = true;
@@ -604,8 +617,9 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 			EnableStandbyMode();
 
 		/*
@@ -620,9 +634,8 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 
 			/*
@@ -631,20 +644,16 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
 
@@ -679,37 +688,32 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
@@ -943,7 +947,7 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
@@ -953,7 +957,7 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,
@@ -983,7 +987,6 @@ InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdown_ptr,

@@ -1156,154 +1159,6 @@ validateRecoveryParameters(void)
 	}
 }
 
-/*
index c7b3ba3e6e..f6cd7d954c 100644
 
 	/*
 
 	/*
@@ -310,19 +310,11 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 
 			if (ti->path == NULL)
 			{
-				struct stat statbuf;

@@ -334,15 +326,14 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 
-				/* ... and pg_control after everything else. */
-				if (lstat(XLOG_CONTROL_FILE, &statbuf) != 0)
-					ereport(ERROR,
-							(errcode_for_file_access(),
-							 errmsg("could not stat file \"%s\": %m",
-									XLOG_CONTROL_FILE)));
-				sendFile(sink, XLOG_CONTROL_FILE, XLOG_CONTROL_FILE, &statbuf,
-						 false, InvalidOid, InvalidOid,
-						 InvalidRelFileNumber, 0, &manifest);
+				/* End the backup before sending pg_control */
+				basebackup_progress_wait_wal_archive(&state);
+				do_pg_backup_stop(backup_state, !opt->nowait);
+
+				/* Send copy of pg_control containing recovery info */
+				sendFileWithContent(sink, XLOG_CONTROL_FILE,
+									(char *)backup_state->controlFile,
+									PG_CONTROL_FILE_SIZE, &manifest);
 			}
 			else
 			{
@@ -376,9 +367,6 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 			}
 		}

@@ -1051,7 +1039,6 @@ sendFileWithContent(bbsink *sink, const char *filename, const char *content,
 	/*
 	 * Construct a stat struct for the file we're injecting in the tar.
 	 */
-
 	/* Windows doesn't have the concept of uid and gid */
 #ifdef WIN32
 	statbuf.st_uid = 0;
diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql
index 4206752881..1f37719cf2 100644
--- a/src/backend/catalog/system_functions.sql
+++ b/src/backend/catalog/system_functions.sql
@@ -384,13 +384,15 @@ BEGIN ATOMIC
 END;

 
diff --git a/src/backend/utils/misc/pg_controldata.c b/src/backend/utils/misc/pg_controldata.c
index a1003a464d..44c4e987ce 100644
--- a/src/backend/utils/misc/pg_controldata.c
+++ b/src/backend/utils/misc/pg_controldata.c
@@ -163,8 +163,8 @@ pg_control_checkpoint(PG_FUNCTION_ARGS)
 Datum
 pg_control_recovery(PG_FUNCTION_ARGS)
 {
-	Datum		values[5];
-	bool		nulls[5];
+	Datum		values[9];
+	bool		nulls[9];
 	TupleDesc	tupdesc;
 	HeapTuple	htup;
 	ControlFileData *ControlFile;
@@ -187,15 +187,27 @@ pg_control_recovery(PG_FUNCTION_ARGS)
 	values[1] = Int32GetDatum(ControlFile->minRecoveryPointTLI);
 	nulls[1] = false;
 
-	values[2] = LSNGetDatum(ControlFile->backupStartPoint);
+	values[2] = LSNGetDatum(ControlFile->backupCheckPoint);
 	nulls[2] = false;
 
-	values[3] = LSNGetDatum(ControlFile->backupEndPoint);
+	values[3] = LSNGetDatum(ControlFile->backupStartPoint);
 	nulls[3] = false;
 
-	values[4] = BoolGetDatum(ControlFile->backupEndRequired);
+	values[4] = Int32GetDatum(ControlFile->backupStartPointTLI);
 	nulls[4] = false;
 
+	values[5] = LSNGetDatum(ControlFile->backupEndPoint);
+	nulls[5] = false;
+
+	values[6] = BoolGetDatum(ControlFile->backupRecoveryRequired);
+	nulls[6] = false;
+
+	values[7] = BoolGetDatum(ControlFile->backupFromStandby);
+	nulls[7] = false;
+
+	values[8] = BoolGetDatum(ControlFile->backupEndRequired);
+	nulls[8] = false;
+
 	htup = heap_form_tuple(tupdesc, values, nulls);
 
 	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
diff --git a/src/bin/pg_basebackup/t/010_pg_basebackup.pl b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
index b9f5e1266b..c655cb0335 100644
--- a/src/bin/pg_basebackup/t/010_pg_basebackup.pl
+++ b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
@@ -171,8 +171,8 @@ SKIP:

 
 
 $node->command_ok(
 	[
index 93e0837947..cc515b622f 100644
index 3ae3fc06df..255101ff3a 100644
 
 	/*
index ecadd69dc5..213f4e71b8 100644
 
 	/*
 
 	/*
index bfd44a284e..6b23ed4a1c 100644
 
@@ -651,10 +648,10 @@ perform_rewind(filemap_t *filemap, rewind_source *source,
 	}
 
 	if (showprogress)
-		pg_log_info("creating backup label and updating control file");
+		pg_log_info("updating control file");
 
 	/*
 
 	/*

-
-/*
index a14126d164..3aac6839a7 100644
 
index 1611358137..9be80a4f7d 100644

 /* Structure to hold backup state. */
@@ -33,9 +34,16 @@ typedef struct BackupState
 	XLogRecPtr	stoppoint;		/* backup stop WAL location */
 	TimeLineID	stoptli;		/* backup stop TLI */
 	pg_time_t	stoptime;		/* backup stop time */
+
+	/*
+	 * After pg_backup_stop() returns this field will contain a copy of
+	 * pg_control that should be stored with the backup. Fields have been
+	 * updated for recovery and the CRC has been recalculated. Bytes after
+	 * sizeof(ControlFileData) are zeroed.
+	 */
+	uint8_t controlFile[PG_CONTROL_FILE_SIZE];
 } BackupState;

index ee0bc74278..981266f734 100644

 /*
index 2ae72e3b26..0ea2e73368 100644
@@ -160,14 +163,28 @@ typedef struct ControlFileData
+	 * by a backup or pg_rewind and recovery settings need to be copied to the
+	 * appropriate fields. It will be set to false when the settings have been
+	 * copied.
 
 	/*
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index fb58dee3bc..16346f0540 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6427,13 +6427,17 @@
   prosrc => 'pg_terminate_backend' },
 { oid => '2172', descr => 'prepare for taking an online backup',
   proname => 'pg_backup_start', provolatile => 'v', proparallel => 'r',
-  prorettype => 'pg_lsn', proargtypes => 'text bool',
+  prorettype => 'record', proargtypes => 'text bool',
+  proallargtypes => '{text,bool,pg_lsn,int8,timestamptz}',
+  proargmodes => '{i,i,o,o,o}',
+  proargnames => '{label,fast,lsn,timeline_id,start}',
   prosrc => 'pg_backup_start' },
 { oid => '2739', descr => 'finish taking an online backup',
   proname => 'pg_backup_stop', provolatile => 'v', proparallel => 'r',
   prorettype => 'record', proargtypes => 'bool',
-  proallargtypes => '{bool,pg_lsn,text,text}', proargmodes => '{i,o,o,o}',
-  proargnames => '{wait_for_archive,lsn,labelfile,spcmapfile}',
+  proallargtypes => '{bool,bytea,text,pg_lsn,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o}',
+  proargnames => '{wait_for_archive,pg_control_file,tablespace_map_file,lsn,timeline_id,stop}',
   prosrc => 'pg_backup_stop' },
 { oid => '3436', descr => 'promote standby server',
   proname => 'pg_promote', provolatile => 'v', prorettype => 'bool',
@@ -11917,9 +11921,9 @@
 { oid => '3443',
   descr => 'pg_controldata recovery state information as a function',
   proname => 'pg_control_recovery', provolatile => 'v', prorettype => 'record',
-  proargtypes => '', proallargtypes => '{pg_lsn,int4,pg_lsn,pg_lsn,bool}',
-  proargmodes => '{o,o,o,o,o}',
-  proargnames => '{min_recovery_end_lsn,min_recovery_end_timeline,backup_start_lsn,backup_end_lsn,end_of_backup_record_required}',
+  proargtypes => '', proallargtypes => '{pg_lsn,int4,pg_lsn,pg_lsn,int4,pg_lsn,bool,bool,bool}',
+  proargmodes => '{o,o,o,o,o,o,o,o,o}',
+  proargnames => '{min_recovery_end_lsn,min_recovery_end_timeline,backup_checkpoint_lsn,backup_start_lsn,backup_start_tli,backup_end_lsn,backup_recovery_required,backup_from_standby,end_of_backup_record_required}',
   prosrc => 'pg_control_recovery' },
 
 { oid => '3444',
-- 
2.34.1

---

From: David Steele <[email-masked]>
Date: Mon, 20 Nov 2023 09:50:56 -0400

> you've proposed attached.)

Ugh, I must have hit reply instead of reply all. It's a rookie error and 
you hate to see it.

> lose any data related to the removal of the backup_label file.

This looks right to me.

> US, a lot of folks will not have the time to monitor what's happening

Timing sounds good to me.

> the backup_label file gone without the end timestamps in the control

Yeah, the end time is very important for recovery scenarios. We 
definitely need that recorded somewhere.

> on HEAD to reset everything, as well..

I'd rather reset everything for now (as we do now) and think about 
keeping these values as a separate patch. It may be that we don't want 
to keep all of them, or we need a separate flag to say recovery was 
completed. We are accumulating a lot of booleans here, maybe we need a 
state var (recoveryRequired, recoveryInProgress, recoveryComplete) and 
then define which other vars are valid in each state.

Regards,
-David

---

From: Robert Haas <[email-masked]>
Date: Mon, 20 Nov 2023 11:11:13 -0500

> lose any data related to the removal of the backup_label file.

I think we need more votes to make a change this big. I have a
concern, which I think I've expressed before, that we keep whacking
around the backup APIs, and that has a cost which is potentially
larger than the benefits. The last time we changed the API, we changed
pg_stop_backup to pg_backup_stop, but this doesn't do that, and I
wonder if that's OK. Even if it is, do we really want to change this
API around again after such a short time?

That said, I don't have an intrinsic problem with moving this
information from the backup_label to the backup_manifest file since it
is purely informational. I do think there should perhaps be some
additions to the test cases, though.

I am concerned about the interaction of this proposal with incremental
backup. When you take an incremental backup, you get something that
looks a lot like a usable data directory but isn't. To prevent that
from causing avoidable disasters, the present version of the patch
adds INCREMENTAL FROM LSN and INCREMENTAL FROM TLI fields to the
backup_label. pg_combinebackup knows to look for those fields, and the
server knows that if they are present it should refuse to start. With
this change, though, I suppose those fields would end up in
pg_control. But that does not feel entirely great, because we have a
goal of keeping the amount of real data in pg_control below 512 bytes,
the traditional sector size, and this adds another 12 bytes of stuff
to that file that currently doesn't need to be there. I feel like
that's kind of a problem.

But my main point here is ... if we have a few more senior hackers
weigh in and vote in favor of this change, well then that's one thing.
But IMHO a discussion that's mostly between 2 people is not nearly a
strong enough consensus to justify this amount of disruption.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

---

From: Michael Paquier <[email-masked]>
Date: Tue, 21 Nov 2023 08:37:01 +0900

> API around again after such a short time?

Agreed.

> additions to the test cases, though.

Yep, cool.  Even if we decide to not go with what's discussed in this
patch, I think that's useful for some users at the end to get more
redundancy, as well.  And that's in a format easier to parse.

> that's kind of a problem.

I don't recall one time where the addition of new fields to the
control file was easy to discuss because of its 512B hard limit.
Anyway, putting the addition aside for a second, and I've not looked
at the incremental backup patch, does the removal of the backup_label
make the combine logic more complicated, or that's just moving a chunk
of code to do a control file lookup instead of a backup_file parsing?
Making the information less readable is definitely an issue for me.  A
different alternative that I've mentioned upthread is to keep an
equivalent of the backup_label and rename it to something like
backup.debug or similar, with a name good enough to tell people that
we don't care about it being removed.
--
Michael

---

From: vignesh C <[email-masked]>
Date: Fri, 26 Jan 2024 18:27:30 +0530

> on HEAD to reset everything, as well..

CFBot shows that the patch does not apply anymore as in [1]:

=== Applying patches on top of PostgreSQL commit ID
7014c9a4bba2d1b67d60687afb5b2091c1d07f73 ===
=== applying patch ./recovery-in-pgcontrol-v7-0001-add-info-to-manifest.patch
patching file doc/src/sgml/backup-manifest.sgml
patching file src/backend/backup/backup_manifest.c
patching file src/backend/backup/basebackup.c
Hunk #1 succeeded at 238 (offset 13 lines).
Hunk #2 succeeded at 258 (offset 13 lines).
Hunk #3 succeeded at 399 (offset 17 lines).
Hunk #4 succeeded at 652 (offset 17 lines).
can't find file to patch at input line 219
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff --git a/src/bin/pg_verifybackup/parse_manifest.c
b/src/bin/pg_verifybackup/parse_manifest.c
|index bf0227c668..408af88e58 100644
|--- a/src/bin/pg_verifybackup/parse_manifest.c
|+++ b/src/bin/pg_verifybackup/parse_manifest.c
--------------------------
No file to patch.  Skipping patch.
9 out of 9 hunks ignored
patching file src/include/backup/backup_manifest.h

Please post an updated version for the same.

[1] - http://cfbot.cputube.org/patch_46_3511.log

Regards,
Vignesh

---

From: Michael Paquier <[email-masked]>
Date: Mon, 29 Jan 2024 08:11:32 +0900

> [1] - http://cfbot.cputube.org/patch_46_3511.log

With the recent introduction of incremental backups that depend on
backup_label and the rather negative feedback received, I think that
it would be better to return this entry as RwF for now.  What do you
think?
--
Michael

---

From: David Steele <[email-masked]>
Date: Sun, 28 Jan 2024 19:28:41 -0400

> it would be better to return this entry as RwF for now.  What do you

I've been thinking it makes little sense to update the patch. It would 
be a lot of work with all the new changes for incremental backup and 
since Andres and Robert appear to be very against the idea, I doubt it 
would be worth the effort.

I have withdrawn the patch.

Regards,
-David