Allow pg_basebackup from standby node with safety checking.

Base backup follows recommended procedure, plus goes to great
lengths to ensure that partial page writes are avoided.

Jun Ishizuka and Fujii Masao, with minor modifications

3 files changed, 13 insertions, 2 deletions

diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 1ddf4bf15f9..f8aecef665b 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -192,6 +192,7 @@ extern int	XLogArchiveTimeout;
 extern bool XLogArchiveMode;
 extern char *XLogArchiveCommand;
 extern bool EnableHotStandby;
+extern bool fullPageWrites;
 extern bool log_checkpoints;
 
 /* WAL levels */
@@ -307,6 +308,7 @@ extern void CreateCheckPoint(int flags);
 extern bool CreateRestartPoint(int flags);
 extern void XLogPutNextOid(Oid nextOid);
 extern XLogRecPtr XLogRestorePoint(const char *rpName);
+extern void UpdateFullPageWrites(void);
 extern XLogRecPtr GetRedoRecPtr(void);
 extern XLogRecPtr GetInsertRecPtr(void);
 extern XLogRecPtr GetFlushRecPtr(void);
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index db6380f7de4..b81c1568818 100644
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -71,7 +71,7 @@ typedef struct XLogContRecord
 /*
  * Each page of XLOG file has a header like this:
  */
-#define XLOG_PAGE_MAGIC 0xD069	/* can be used as WAL version indicator */
+#define XLOG_PAGE_MAGIC 0xD070	/* can be used as WAL version indicator */
 
 typedef struct XLogPageHeaderData
 {
diff --git a/src/include/catalog/pg_control.h b/src/include/catalog/pg_control.h
index d0d2e9e39d5..1031e565127 100644
--- a/src/include/catalog/pg_control.h
+++ b/src/include/catalog/pg_control.h
@@ -21,7 +21,7 @@
 
 
 /* Version identifier for this pg_control format */
-#define PG_CONTROL_VERSION	921
+#define PG_CONTROL_VERSION	922
 
 /*
  * Body of CheckPoint XLOG records.  This is declared here because we keep
@@ -33,6 +33,7 @@ typedef struct CheckPoint
 	XLogRecPtr	redo;			/* next RecPtr available when we began to
 								 * create CheckPoint (i.e. REDO start point) */
 	TimeLineID	ThisTimeLineID; /* current TLI */
+	bool			fullPageWrites;	/* current full_page_writes */
 	uint32		nextXidEpoch;	/* higher-order bits of nextXid */
 	TransactionId nextXid;		/* next free XID */
 	Oid			nextOid;		/* next free OID */
@@ -60,6 +61,7 @@ typedef struct CheckPoint
 #define XLOG_BACKUP_END					0x50
 #define XLOG_PARAMETER_CHANGE			0x60
 #define XLOG_RESTORE_POINT				0x70
+#define XLOG_FPW_CHANGE				0x80
 
 
 /*
@@ -138,6 +140,12 @@ typedef struct ControlFileData
 	 * record, to make sure the end-of-backup record corresponds the base
 	 * backup we're recovering from.
 	 *
+	 * backupEndPoint is the backup end location, if we are recovering from
+	 * an online backup which was taken from the standby and haven't reached
+	 * the end of backup yet. It is initialized to the minimum recovery point
+	 * in 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.
+	 *
 	 * 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. If it's false, but backupStartPoint is set, a backup_label
@@ -146,6 +154,7 @@ typedef struct ControlFileData
 	 */
 	XLogRecPtr	minRecoveryPoint;
 	XLogRecPtr	backupStartPoint;
+	XLogRecPtr	backupEndPoint;
 	bool		backupEndRequired;
 
 	/*