Add archive_mode='always' option.

In 'always' mode, the standby independently archives all files it receives
from the primary.

Original patch by Fujii Masao, docs and review by me.

7 files changed, 83 insertions, 27 deletions

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 5f0551a3cbd..0485bb5201e 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -86,7 +86,7 @@ int			min_wal_size = 5;		/* 80 MB */
 int			wal_keep_segments = 0;
 int			XLOGbuffers = -1;
 int			XLogArchiveTimeout = 0;
-bool		XLogArchiveMode = false;
+int			XLogArchiveMode = ARCHIVE_MODE_OFF;
 char	   *XLogArchiveCommand = NULL;
 bool		EnableHotStandby = false;
 bool		fullPageWrites = true;
@@ -140,6 +140,24 @@ const struct config_enum_entry sync_method_options[] = {
 	{NULL, 0, false}
 };
 
+
+/*
+ * Although only "on", "off", and "always" are documented,
+ * we accept all the likely variants of "on" and "off".
+ */
+const struct config_enum_entry archive_mode_options[] = {
+	{"always", ARCHIVE_MODE_ALWAYS, false},
+	{"on", ARCHIVE_MODE_ON, false},
+	{"off", ARCHIVE_MODE_OFF, false},
+	{"true", ARCHIVE_MODE_ON, true},
+	{"false", ARCHIVE_MODE_OFF, true},
+	{"yes", ARCHIVE_MODE_ON, true},
+	{"no", ARCHIVE_MODE_OFF, true},
+	{"1", ARCHIVE_MODE_ON, true},
+	{"0", ARCHIVE_MODE_OFF, true},
+	{NULL, 0, false}
+};
+
 /*
  * Statistics for current checkpoint are collected in this global struct.
  * Because only the checkpointer or a stand-alone backend can perform
@@ -767,7 +785,7 @@ static MemoryContext walDebugCxt = NULL;
 #endif
 
 static void readRecoveryCommandFile(void);
-static void exitArchiveRecovery(TimeLineID endTLI, XLogSegNo endLogSegNo);
+static void exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog);
 static bool recoveryStopsBefore(XLogReaderState *record);
 static bool recoveryStopsAfter(XLogReaderState *record);
 static void recoveryPausesHere(void);
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index f435f65e98b..4c69b738bc1 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -480,7 +480,10 @@ KeepFileRestoredFromArchive(char *path, char *xlogfname)
 	 * Create .done file forcibly to prevent the restored segment from being
 	 * archived again later.
 	 */
-	XLogArchiveForceDone(xlogfname);
+	if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
+		XLogArchiveForceDone(xlogfname);
+	else
+		XLogArchiveNotify(xlogfname);
 
 	/*
 	 * If the existing file was replaced, since walsenders might have it open,
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index a9f20ac1b44..36440cbdccd 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -828,9 +828,9 @@ PostmasterMain(int argc, char *argv[])
 		write_stderr("%s: max_wal_senders must be less than max_connections\n", progname);
 		ExitPostmaster(1);
 	}
-	if (XLogArchiveMode && wal_level == WAL_LEVEL_MINIMAL)
+	if (XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_MINIMAL)
 		ereport(ERROR,
-				(errmsg("WAL archival (archive_mode=on) requires wal_level \"archive\", \"hot_standby\", or \"logical\"")));
+				(errmsg("WAL archival cannot be enabled when wal_level is \"minimal\"")));
 	if (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL)
 		ereport(ERROR,
 				(errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"archive\", \"hot_standby\", or \"logical\"")));
@@ -1645,13 +1645,21 @@ ServerLoop(void)
 				start_autovac_launcher = false; /* signal processed */
 		}
 
-		/* If we have lost the archiver, try to start a new one */
-		if (XLogArchivingActive() && PgArchPID == 0 && pmState == PM_RUN)
-			PgArchPID = pgarch_start();
-
-		/* If we have lost the stats collector, try to start a new one */
-		if (PgStatPID == 0 && pmState == PM_RUN)
-			PgStatPID = pgstat_start();
+		/*
+		 * If we have lost the archiver, try to start a new one.
+		 *
+		 * If WAL archiving is enabled always, we try to start a new archiver
+		 * even during recovery.
+		 */
+		if (PgArchPID == 0 && wal_level >= WAL_LEVEL_ARCHIVE)
+		{
+			if ((pmState == PM_RUN && XLogArchiveMode > ARCHIVE_MODE_OFF) ||
+				((pmState == PM_RECOVERY || pmState == PM_HOT_STANDBY) &&
+				 XLogArchiveMode == ARCHIVE_MODE_ALWAYS))
+			{
+				PgArchPID = pgarch_start();
+			}
+		}
 
 		/* If we need to signal the autovacuum launcher, do so now */
 		if (avlauncher_needs_signal)
@@ -4807,6 +4815,17 @@ sigusr1_handler(SIGNAL_ARGS)
 		Assert(BgWriterPID == 0);
 		BgWriterPID = StartBackgroundWriter();
 
+		/*
+		 * Start the archiver if we're responsible for (re-)archiving received
+		 * files.
+		 */
+		Assert(PgArchPID == 0);
+		if (wal_level >= WAL_LEVEL_ARCHIVE &&
+			XLogArchiveMode == ARCHIVE_MODE_ALWAYS)
+		{
+			PgArchPID = pgarch_start();
+		}
+
 		pmState = PM_RECOVERY;
 	}
 	if (CheckPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY) &&
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 9c7710f0dbd..41e57f24397 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -540,7 +540,10 @@ WalReceiverMain(void)
 			 * being archived later.
 			 */
 			XLogFileName(xlogfname, recvFileTLI, recvSegNo);
-			XLogArchiveForceDone(xlogfname);
+			if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
+				XLogArchiveForceDone(xlogfname);
+			else
+				XLogArchiveNotify(xlogfname);
 		}
 		recvFile = -1;
 
@@ -897,7 +900,10 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 				 * from being archived later.
 				 */
 				XLogFileName(xlogfname, recvFileTLI, recvSegNo);
-				XLogArchiveForceDone(xlogfname);
+				if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
+					XLogArchiveForceDone(xlogfname);
+				else
+					XLogArchiveNotify(xlogfname);
 			}
 			recvFile = -1;
 
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 222228ae5a7..3038d7c9dda 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -396,6 +396,7 @@ static const struct config_enum_entry row_security_options[] = {
  * Options for enum values stored in other modules
  */
 extern const struct config_enum_entry wal_level_options[];
+extern const struct config_enum_entry archive_mode_options[];
 extern const struct config_enum_entry sync_method_options[];
 extern const struct config_enum_entry dynamic_shared_memory_options[];
 
@@ -1530,16 +1531,6 @@ static struct config_bool ConfigureNamesBool[] =
 	},
 
 	{
-		{"archive_mode", PGC_POSTMASTER, WAL_ARCHIVING,
-			gettext_noop("Allows archiving of WAL files using archive_command."),
-			NULL
-		},
-		&XLogArchiveMode,
-		false,
-		NULL, NULL, NULL
-	},
-
-	{
 		{"hot_standby", PGC_POSTMASTER, REPLICATION_STANDBY,
 			gettext_noop("Allows connections and queries during recovery."),
 			NULL
@@ -3552,6 +3543,16 @@ static struct config_enum ConfigureNamesEnum[] =
 	},
 
 	{
+		{"archive_mode", PGC_POSTMASTER, WAL_ARCHIVING,
+			gettext_noop("Allows archiving of WAL files using archive_command."),
+			NULL
+		},
+		&XLogArchiveMode,
+		ARCHIVE_MODE_OFF, archive_mode_options,
+		NULL, NULL, NULL
+	},
+
+	{
 		{"trace_recovery_messages", PGC_SIGHUP, DEVELOPER_OPTIONS,
 			gettext_noop("Enables logging of recovery-related debugging information."),
 			gettext_noop("Each level includes all the levels that follow it. The later"
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 110983f1764..06dfc067b03 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -206,7 +206,7 @@
 
 # - Archiving -
 
-#archive_mode = off		# allows archiving to be done
+#archive_mode = off		# enables archiving; off, on, or always
 				# (change requires restart)
 #archive_command = ''		# command to use to archive a logfile segment
 				# placeholders: %p = path of file to archive
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 961e0506221..9567379f49d 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -98,7 +98,6 @@ extern int	wal_keep_segments;
 extern int	XLOGbuffers;
 extern int	XLogArchiveTimeout;
 extern int	wal_retrieve_retry_interval;
-extern bool XLogArchiveMode;
 extern char *XLogArchiveCommand;
 extern bool EnableHotStandby;
 extern bool fullPageWrites;
@@ -108,6 +107,15 @@ extern bool log_checkpoints;
 
 extern int	CheckPointSegments;
 
+/* Archive modes */
+typedef enum ArchiveMode
+{
+	ARCHIVE_MODE_OFF = 0,	/* disabled */
+	ARCHIVE_MODE_ON,		/* enabled while server is running normally */
+	ARCHIVE_MODE_ALWAYS		/* enabled always (even during recovery) */
+} ArchiveMode;
+extern int	XLogArchiveMode;
+
 /* WAL levels */
 typedef enum WalLevel
 {
@@ -118,7 +126,8 @@ typedef enum WalLevel
 } WalLevel;
 extern int	wal_level;
 
-#define XLogArchivingActive()	(XLogArchiveMode && wal_level >= WAL_LEVEL_ARCHIVE)
+#define XLogArchivingActive() \
+	(XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level >= WAL_LEVEL_ARCHIVE)
 #define XLogArchiveCommandSet() (XLogArchiveCommand[0] != '\0')
 
 /*