From 1d577f5e49400465bd8cc3f91b67d03a551528c3 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 9 Nov 2008 17:51:15 +0000
Subject: [PATCH] Add a startup check that pg_xlog and pg_xlog/archive_status
exist. If the latter doesn't exist, automatically recreate it. (We don't do
this for pg_xlog, though, per discussion.)
Jonah Harris
---
doc/src/sgml/backup.sgml | 4 +--
src/backend/access/transam/xlog.c | 57 ++++++++++++++++++++++++++++++-
2 files changed, 57 insertions(+), 4 deletions(-)
diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index 3f62e8fa5a0..1c9b5cfb4bd 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.120 2008/07/18 17:33:17 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.121 2008/11/09 17:51:15 tgl Exp $ -->
<chapter id="backup">
<title>Backup and Restore</title>
@@ -945,8 +945,6 @@ SELECT pg_stop_backup();
If you didn't archive <filename>pg_xlog/</> at all, then recreate it,
being careful to ensure that you re-establish it as a symbolic link
if you had it set up that way before.
- Be sure to recreate the subdirectory
- <filename>pg_xlog/archive_status/</> as well.
</para>
</listitem>
<listitem>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 77ab05b53d6..f48dd5f7812 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.321 2008/10/31 15:04:59 heikki Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.322 2008/11/09 17:51:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -416,6 +416,7 @@ static bool RestoreArchivedFile(char *path, const char *xlogfname,
const char *recovername, off_t expectedSize);
static void PreallocXlogFiles(XLogRecPtr endptr);
static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr);
+static void ValidateXLOGDirectoryStructure(void);
static void CleanupBackupHistory(void);
static XLogRecord *ReadRecord(XLogRecPtr *RecPtr, int emode);
static bool ValidXLOGHeader(XLogPageHeader hdr, int emode);
@@ -2824,6 +2825,53 @@ RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr)
FreeDir(xldir);
}
+/*
+ * Verify whether pg_xlog and pg_xlog/archive_status exist.
+ * If the latter does not exist, recreate it.
+ *
+ * It is not the goal of this function to verify the contents of these
+ * directories, but to help in cases where someone has performed a cluster
+ * copy for PITR purposes but omitted pg_xlog from the copy.
+ *
+ * We could also recreate pg_xlog if it doesn't exist, but a deliberate
+ * policy decision was made not to. It is fairly common for pg_xlog to be
+ * a symlink, and if that was the DBA's intent then automatically making a
+ * plain directory would result in degraded performance with no notice.
+ */
+static void
+ValidateXLOGDirectoryStructure(void)
+{
+ char path[MAXPGPATH];
+ struct stat stat_buf;
+
+ /* Check for pg_xlog; if it doesn't exist, error out */
+ if (stat(XLOGDIR, &stat_buf) != 0 ||
+ !S_ISDIR(stat_buf.st_mode))
+ ereport(FATAL,
+ (errmsg("required WAL directory \"%s\" does not exist",
+ XLOGDIR)));
+
+ /* Check for archive_status */
+ snprintf(path, MAXPGPATH, XLOGDIR "/archive_status");
+ if (stat(path, &stat_buf) == 0)
+ {
+ /* Check for weird cases where it exists but isn't a directory */
+ if (!S_ISDIR(stat_buf.st_mode))
+ ereport(FATAL,
+ (errmsg("required WAL directory \"%s\" does not exist",
+ path)));
+ }
+ else
+ {
+ ereport(LOG,
+ (errmsg("creating missing WAL directory \"%s\"", path)));
+ if (mkdir(path, 0700) < 0)
+ ereport(FATAL,
+ (errmsg("could not create missing directory \"%s\": %m",
+ path)));
+ }
+}
+
/*
* Remove previous backup history files. This also retries creation of
* .ready files for any backup history files for which XLogArchiveNotify
@@ -4878,6 +4926,13 @@ StartupXLOG(void)
pg_usleep(60000000L);
#endif
+ /*
+ * Verify that pg_xlog and pg_xlog/archive_status exist. In cases where
+ * someone has performed a copy for PITR, these directories may have
+ * been excluded and need to be re-created.
+ */
+ ValidateXLOGDirectoryStructure();
+
/*
* Initialize on the assumption we want to recover to the same timeline
* that's active according to pg_control.
--
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