min-consistent-update-v3.patch

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 493f1db7b9..74692a128d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2723,9 +2723,13 @@ UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force)
 	 * i.e., we're doing crash recovery.  We never modify the control file's
 	 * value in that case, so we can short-circuit future checks here too. The
 	 * local values of minRecoveryPoint and minRecoveryPointTLI should not be
-	 * updated until crash recovery finishes.
+	 * updated until crash recovery finishes.  We only do this for the startup
+	 * process as it should not update its own reference of minRecoveryPoint
+	 * until it has finished crash recovery to make sure that all WAL
+	 * available is replayed in this case.  This also saves from extra locks
+	 * taken on the control file from the startup process.
 	 */
-	if (XLogRecPtrIsInvalid(minRecoveryPoint))
+	if (XLogRecPtrIsInvalid(minRecoveryPoint) && InRecovery)
 	{
 		updateMinRecoveryPoint = false;
 		return;
@@ -2737,7 +2741,9 @@ UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force)
 	minRecoveryPoint = ControlFile->minRecoveryPoint;
 	minRecoveryPointTLI = ControlFile->minRecoveryPointTLI;
 
-	if (force || minRecoveryPoint < lsn)
+	if (XLogRecPtrIsInvalid(minRecoveryPoint))
+		updateMinRecoveryPoint = false;
+	else if (force || minRecoveryPoint < lsn)
 	{
 		XLogRecPtr	newMinRecoveryPoint;
 		TimeLineID	newMinRecoveryPointTLI;
@@ -3124,12 +3130,15 @@ XLogNeedsFlush(XLogRecPtr record)
 	if (RecoveryInProgress())
 	{
 		/*
-		 * An invalid minRecoveryPoint means that we need to recover all the
-		 * WAL, i.e., we're doing crash recovery.  We never modify the control
-		 * file's value in that case, so we can short-circuit future checks
-		 * here too.
+		 * An invalid minRecoveryPoint on the startup process means that we
+		 * need to recover all the WAL, i.e., we're doing crash recovery.  We
+		 * never modify the control file's value in that case, so we can
+		 * short-circuit future checks here too.  This triggers a quick exit
+		 * path for the startup process, which cannot update its local copy of
+		 * minRecoveryPoint as long as it has not replayed all WAL available
+		 * when doing crash recovery.
 		 */
-		if (XLogRecPtrIsInvalid(minRecoveryPoint))
+		if (XLogRecPtrIsInvalid(minRecoveryPoint) && InRecovery)
 			updateMinRecoveryPoint = false;
 
 		/* Quick exit if already known to be updated or cannot be updated */
@@ -3146,6 +3155,12 @@ XLogNeedsFlush(XLogRecPtr record)
 		minRecoveryPointTLI = ControlFile->minRecoveryPointTLI;
 		LWLockRelease(ControlFileLock);
 
+		/*
+		 * No other process than the startup doesn't reach here before crash
+		 * recovery ends. So minRecoveryPoint must have a valid value here.
+		 */
+		Assert(minRecoveryPoint != InvalidXLogRecPtr);
+
 		/* check again */
 		return record > minRecoveryPoint;
 	}