Hi,
The .backup files written to the archive (if archiving is on) are very
similar to the backup_label that's written/returned by
pg_stop_backup()/pg_backup_stop(), they just have a few extra lines
about the end of backup process that are missing from backup_label.
The parser in xlogrecovery.c however barfs on them because it does not
expect the additional STOP WAL LOCATION on line 2.
The attached makes parsing this line optional, so that one can use those
.backup files in place of backup_label. This is e.g. useful if the
backup_label got lost or the output of pg_stop_backup() was not
captured.
Michael
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>From 00b1b245f74a0496a4d60cfafff92735dbe73d22 Mon Sep 17 00:00:00 2001
From: Michael Banck <michael.ba...@credativ.de>
Date: Mon, 22 Aug 2022 16:20:14 +0200
Subject: [PATCH] Allow usage of archive .backup files as backup_label.
This lets the backup_label parser not bail if STOP WAL LOCATION is encountered,
which is the only meaningful difference between an archive .backup file and a
backup_label file, thus allowing to just copy the corresponding .backup file
from the archive as backup_label, in case the backup_label file got lost or was
never recorded.
---
src/backend/access/transam/xlogrecovery.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index a59a0e826b..a95946e391 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -1149,6 +1149,7 @@ read_backup_label(XLogRecPtr *checkPointLoc, TimeLineID *backupLabelTLI,
bool *backupEndRequired, bool *backupFromStandby)
{
char startxlogfilename[MAXFNAMELEN];
+ char stopxlogfilename[MAXFNAMELEN];
TimeLineID tli_from_walseg,
tli_from_file;
FILE *lfp;
@@ -1183,7 +1184,10 @@ read_backup_label(XLogRecPtr *checkPointLoc, TimeLineID *backupLabelTLI,
/*
* 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).
+ * format). Also allow STOP WAL LOCATION to be in the file. This line does
+ * not appear in backup_label, but it is written to the corresponding
+ * .backup file and allows users to rename or copy that file to
+ * backup_label without further editing.
*/
if (fscanf(lfp, "START WAL LOCATION: %X/%X (file %08X%16s)%c",
&hi, &lo, &tli_from_walseg, startxlogfilename, &ch) != 5 || ch != '\n')
@@ -1192,6 +1196,11 @@ read_backup_label(XLogRecPtr *checkPointLoc, TimeLineID *backupLabelTLI,
errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));
RedoStartLSN = ((uint64) hi) << 32 | lo;
RedoStartTLI = tli_from_walseg;
+ if (fscanf(lfp, "STOP WAL LOCATION: %X/%X (file %*08X%16s)%c",
+ &hi, &lo, stopxlogfilename, &ch) == 4)
+ ereport(DEBUG1,
+ (errmsg_internal("stop wal location %X/%X in file \"%s\"",
+ hi, lo, BACKUP_LABEL_FILE)));
if (fscanf(lfp, "CHECKPOINT LOCATION: %X/%X%c",
&hi, &lo, &ch) != 3 || ch != '\n')
ereport(FATAL,
--
2.30.2
