From dbc08907e870a30a8a0264f2020933728a9e85f6 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki@enterprisedb.com>
Date: Wed, 28 Jan 2009 11:47:28 +0200
Subject: [PATCH] Fix two bugs: minSafeStartPoint must never move backwards,
 and recoveryLogRestartpoints needs to be accessible to bgwriter.

---
 src/backend/access/transam/xlog.c | 42 ++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 2a645b26c1..30fea49397 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -147,10 +147,13 @@ static char *recoveryRestoreCommand = NULL;
 static bool recoveryTarget = false;
 static bool recoveryTargetExact = false;
 static bool recoveryTargetInclusive = true;
-static bool recoveryLogRestartpoints = false;
 static TransactionId recoveryTargetXid;
 static TimestampTz recoveryTargetTime;
 static TimestampTz recoveryLastXTime = 0;
+/*
+ * log_restartpoints is stored in shared memory because it needs to be
+ * accessed by bgwriter when it performs restartpoints
+ */
 
 /* if recoveryStopsHere returns true, it saves actual stop xid/time here */
 static TransactionId recoveryStopXid;
@@ -346,6 +349,9 @@ typedef struct XLogCtlData
 	XLogRecPtr	lastCheckPointRecPtr;
 	CheckPoint	lastCheckPoint;
 
+	/* Should restartpoints be logged? Taken from recovery.conf */
+	bool		recoveryLogRestartpoints;
+
 	slock_t		info_lck;		/* locks shared variables shown above */
 } XLogCtlData;
 
@@ -2459,15 +2465,20 @@ XLogFileRead(uint32 log, uint32 seg, int emode)
 			 */
 			if (InArchiveRecovery)
 			{
-				uint32 nextLog = log;
-				uint32 nextSeg = seg;
+				XLogRecPtr	nextSegRecPtr;
+				uint32		nextLog = log;
+				uint32		nextSeg = seg;
 
 				NextLogSeg(nextLog, nextSeg);
+				nextSegRecPtr.xlogid = nextLog;
+				nextSegRecPtr.xrecoff = nextSeg * XLogSegSize;
 
 				LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
-				ControlFile->minSafeStartPoint.xlogid = nextLog;
-				ControlFile->minSafeStartPoint.xrecoff = nextSeg * XLogSegSize;
-				UpdateControlFile();
+				if (XLByteLT(ControlFile->minSafeStartPoint, nextSegRecPtr))
+				{
+					ControlFile->minSafeStartPoint = nextSegRecPtr;
+					UpdateControlFile();
+				}
 				LWLockRelease(ControlFileLock);
 			}
 
@@ -4654,7 +4665,7 @@ readRecoveryCommandFile(void)
 			/*
 			 * does nothing if a recovery_target is not also set
 			 */
-			if (!parse_bool(tok2, &recoveryLogRestartpoints))
+			if (!parse_bool(tok2, &XLogCtl->recoveryLogRestartpoints))
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 							errmsg("parameter \"log_restartpoints\" requires a Boolean value")));
@@ -5229,12 +5240,19 @@ StartupXLOG(void)
 			bool		recoveryContinue = true;
 			bool		recoveryApply = true;
 			ErrorContextCallback errcontext;
+			XLogRecPtr	minSafeStartPoint;
 
 			InRedo = true;
 			ereport(LOG,
 					(errmsg("redo starts at %X/%X",
 							ReadRecPtr.xlogid, ReadRecPtr.xrecoff)));
 
+			/*
+			 * Take a local copy of minSafeStartPoint at the beginning of
+			 * recovery, because it's updated as we go.
+			 */
+			minSafeStartPoint = ControlFile->minSafeStartPoint;
+
 			/*
 			 * main redo apply loop
 			 */
@@ -5303,7 +5321,7 @@ StartupXLOG(void)
 				 * latest LSN that recovery could have reached prior to crash.
 				 */
 				if (!reachedSafeStartPoint && 
-					 XLByteLE(ControlFile->minSafeStartPoint, EndRecPtr) && 
+					 XLByteLE(minSafeStartPoint, EndRecPtr) && 
 					 XLByteLE(ControlFile->minRecoveryPoint, EndRecPtr))
 				{
 					reachedSafeStartPoint = true;
@@ -6352,7 +6370,7 @@ CreateRestartPoint(int flags)
 		return;
 	}
 
-	if (recoveryLogRestartpoints)
+	if (XLogCtl->recoveryLogRestartpoints)
 	{
 		/*
 		 * Prepare to accumulate statistics.
@@ -6383,15 +6401,15 @@ CreateRestartPoint(int flags)
 	 */
 
 	/* All real work is done, but log before releasing lock. */
-	if (recoveryLogRestartpoints)
+	if (XLogCtl->recoveryLogRestartpoints)
 		LogCheckpointEnd(flags, true);
 
-	ereport((recoveryLogRestartpoints ? LOG : DEBUG2),
+	ereport((XLogCtl->recoveryLogRestartpoints ? LOG : DEBUG2),
 			(errmsg("recovery restart point at %X/%X",
 					lastCheckPoint.redo.xlogid, lastCheckPoint.redo.xrecoff)));
 
 	if (recoveryLastXTime)
-		ereport((recoveryLogRestartpoints ? LOG : DEBUG2),
+		ereport((XLogCtl->recoveryLogRestartpoints ? LOG : DEBUG2),
 			(errmsg("last completed transaction was at log time %s",
 					timestamptz_to_str(recoveryLastXTime))));
 
-- 
2.39.5