Integrate FullTransactionIds deeper into two-phase code

This refactoring is a follow-up of the work done in 5a1dfde8334b, that
has switched 2PC file names to use FullTransactionIds when written on
disk.  This will help with the integration of a follow-up solution
related to the handling of two-phase files during recovery, to address
older defects while reading these from disk after a crash.

This change is useful in itself as it reduces the need to build the
file names from epoch numbers and TransactionIds, because we can use
directly FullTransactionIds from which the 2PC file names are guessed.
So this avoids a lot of back-and-forth between the FullTransactionIds
retrieved from the file names and how these are passed around in the
internal 2PC logic.

Note that the core of the change is the use of a FullTransactionId
instead of a TransactionId in GlobalTransactionData, that tracks 2PC
file information in shared memory.  The change in TwoPhaseCallback makes
this commit unfit for stable branches.

Noah has contributed a good chunk of this patch.  I have spent some time
on it as well while working on the issues with two-phase state files and
recovery.

Author: Noah Misch <[email protected]>
Co-Authored-by: Michael Paquier <[email protected]>
Discussion: https://postgr.es/m/[email protected]
Discussion: https://postgr.es/m/[email protected]

12 files changed, 200 insertions, 154 deletions

diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 3c06ac45532..7a7afe3edc6 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -1847,7 +1847,7 @@ AtPrepare_MultiXact(void)
  *		Clean up after successful PREPARE TRANSACTION
  */
 void
-PostPrepare_MultiXact(TransactionId xid)
+PostPrepare_MultiXact(FullTransactionId fxid)
 {
 	MultiXactId myOldestMember;
 
@@ -1858,7 +1858,7 @@ PostPrepare_MultiXact(TransactionId xid)
 	myOldestMember = OldestMemberMXactId[MyProcNumber];
 	if (MultiXactIdIsValid(myOldestMember))
 	{
-		ProcNumber	dummyProcNumber = TwoPhaseGetDummyProcNumber(xid, false);
+		ProcNumber	dummyProcNumber = TwoPhaseGetDummyProcNumber(fxid, false);
 
 		/*
 		 * Even though storing MultiXactId is atomic, acquire lock to make
@@ -1896,10 +1896,10 @@ PostPrepare_MultiXact(TransactionId xid)
  *		Recover the state of a prepared transaction at startup
  */
 void
-multixact_twophase_recover(TransactionId xid, uint16 info,
+multixact_twophase_recover(FullTransactionId fxid, uint16 info,
 						   void *recdata, uint32 len)
 {
-	ProcNumber	dummyProcNumber = TwoPhaseGetDummyProcNumber(xid, false);
+	ProcNumber	dummyProcNumber = TwoPhaseGetDummyProcNumber(fxid, false);
 	MultiXactId oldestMember;
 
 	/*
@@ -1917,10 +1917,10 @@ multixact_twophase_recover(TransactionId xid, uint16 info,
  *		Similar to AtEOXact_MultiXact but for COMMIT PREPARED
  */
 void
-multixact_twophase_postcommit(TransactionId xid, uint16 info,
+multixact_twophase_postcommit(FullTransactionId fxid, uint16 info,
 							  void *recdata, uint32 len)
 {
-	ProcNumber	dummyProcNumber = TwoPhaseGetDummyProcNumber(xid, true);
+	ProcNumber	dummyProcNumber = TwoPhaseGetDummyProcNumber(fxid, true);
 
 	Assert(len == sizeof(MultiXactId));
 
@@ -1932,10 +1932,10 @@ multixact_twophase_postcommit(TransactionId xid, uint16 info,
  *		This is actually just the same as the COMMIT case.
  */
 void
-multixact_twophase_postabort(TransactionId xid, uint16 info,
+multixact_twophase_postabort(FullTransactionId fxid, uint16 info,
 							 void *recdata, uint32 len)
 {
-	multixact_twophase_postcommit(xid, info, recdata, len);
+	multixact_twophase_postcommit(fxid, info, recdata, len);
 }
 
 /*
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 73a80559194..8975dc6d3c8 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -159,7 +159,7 @@ typedef struct GlobalTransactionData
 	 */
 	XLogRecPtr	prepare_start_lsn;	/* XLOG offset of prepare record start */
 	XLogRecPtr	prepare_end_lsn;	/* XLOG offset of prepare record end */
-	TransactionId xid;			/* The GXACT id */
+	FullTransactionId fxid;		/* The GXACT full xid */
 
 	Oid			owner;			/* ID of user that executed the xact */
 	ProcNumber	locking_backend;	/* backend currently working on the xact */
@@ -197,6 +197,7 @@ static GlobalTransaction MyLockedGxact = NULL;
 
 static bool twophaseExitRegistered = false;
 
+static void PrepareRedoRemoveFull(FullTransactionId fxid, bool giveWarning);
 static void RecordTransactionCommitPrepared(TransactionId xid,
 											int nchildren,
 											TransactionId *children,
@@ -216,19 +217,19 @@ static void RecordTransactionAbortPrepared(TransactionId xid,
 										   int nstats,
 										   xl_xact_stats_item *stats,
 										   const char *gid);
-static void ProcessRecords(char *bufptr, TransactionId xid,
+static void ProcessRecords(char *bufptr, FullTransactionId fxid,
 						   const TwoPhaseCallback callbacks[]);
 static void RemoveGXact(GlobalTransaction gxact);
 
 static void XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len);
-static char *ProcessTwoPhaseBuffer(TransactionId xid,
+static char *ProcessTwoPhaseBuffer(FullTransactionId fxid,
 								   XLogRecPtr prepare_start_lsn,
 								   bool fromdisk, bool setParent, bool setNextXid);
-static void MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid,
+static void MarkAsPreparingGuts(GlobalTransaction gxact, FullTransactionId fxid,
 								const char *gid, TimestampTz prepared_at, Oid owner,
 								Oid databaseid);
-static void RemoveTwoPhaseFile(TransactionId xid, bool giveWarning);
-static void RecreateTwoPhaseFile(TransactionId xid, void *content, int len);
+static void RemoveTwoPhaseFile(FullTransactionId fxid, bool giveWarning);
+static void RecreateTwoPhaseFile(FullTransactionId fxid, void *content, int len);
 
 /*
  * Initialization of shared memory
@@ -356,7 +357,7 @@ PostPrepare_Twophase(void)
  *		Reserve the GID for the given transaction.
  */
 GlobalTransaction
-MarkAsPreparing(TransactionId xid, const char *gid,
+MarkAsPreparing(FullTransactionId fxid, const char *gid,
 				TimestampTz prepared_at, Oid owner, Oid databaseid)
 {
 	GlobalTransaction gxact;
@@ -407,7 +408,7 @@ MarkAsPreparing(TransactionId xid, const char *gid,
 	gxact = TwoPhaseState->freeGXacts;
 	TwoPhaseState->freeGXacts = gxact->next;
 
-	MarkAsPreparingGuts(gxact, xid, gid, prepared_at, owner, databaseid);
+	MarkAsPreparingGuts(gxact, fxid, gid, prepared_at, owner, databaseid);
 
 	gxact->ondisk = false;
 
@@ -430,11 +431,13 @@ MarkAsPreparing(TransactionId xid, const char *gid,
  * Note: This function should be called with appropriate locks held.
  */
 static void
-MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
-					TimestampTz prepared_at, Oid owner, Oid databaseid)
+MarkAsPreparingGuts(GlobalTransaction gxact, FullTransactionId fxid,
+					const char *gid, TimestampTz prepared_at, Oid owner,
+					Oid databaseid)
 {
 	PGPROC	   *proc;
 	int			i;
+	TransactionId xid = XidFromFullTransactionId(fxid);
 
 	Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
 
@@ -479,7 +482,7 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
 	proc->subxidStatus.count = 0;
 
 	gxact->prepared_at = prepared_at;
-	gxact->xid = xid;
+	gxact->fxid = fxid;
 	gxact->owner = owner;
 	gxact->locking_backend = MyProcNumber;
 	gxact->valid = false;
@@ -797,12 +800,12 @@ pg_prepared_xact(PG_FUNCTION_ARGS)
  * caller had better hold it.
  */
 static GlobalTransaction
-TwoPhaseGetGXact(TransactionId xid, bool lock_held)
+TwoPhaseGetGXact(FullTransactionId fxid, bool lock_held)
 {
 	GlobalTransaction result = NULL;
 	int			i;
 
-	static TransactionId cached_xid = InvalidTransactionId;
+	static FullTransactionId cached_fxid = {InvalidTransactionId};
 	static GlobalTransaction cached_gxact = NULL;
 
 	Assert(!lock_held || LWLockHeldByMe(TwoPhaseStateLock));
@@ -811,7 +814,7 @@ TwoPhaseGetGXact(TransactionId xid, bool lock_held)
 	 * During a recovery, COMMIT PREPARED, or ABORT PREPARED, we'll be called
 	 * repeatedly for the same XID.  We can save work with a simple cache.
 	 */
-	if (xid == cached_xid)
+	if (FullTransactionIdEquals(fxid, cached_fxid))
 		return cached_gxact;
 
 	if (!lock_held)
@@ -821,7 +824,7 @@ TwoPhaseGetGXact(TransactionId xid, bool lock_held)
 	{
 		GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
 
-		if (gxact->xid == xid)
+		if (FullTransactionIdEquals(gxact->fxid, fxid))
 		{
 			result = gxact;
 			break;
@@ -832,9 +835,10 @@ TwoPhaseGetGXact(TransactionId xid, bool lock_held)
 		LWLockRelease(TwoPhaseStateLock);
 
 	if (result == NULL)			/* should not happen */
-		elog(ERROR, "failed to find GlobalTransaction for xid %u", xid);
+		elog(ERROR, "failed to find GlobalTransaction for xid %u",
+			 XidFromFullTransactionId(fxid));
 
-	cached_xid = xid;
+	cached_fxid = fxid;
 	cached_gxact = result;
 
 	return result;
@@ -881,7 +885,7 @@ TwoPhaseGetXidByVirtualXID(VirtualTransactionId vxid,
 				*have_more = true;
 				break;
 			}
-			result = gxact->xid;
+			result = XidFromFullTransactionId(gxact->fxid);
 		}
 	}
 
@@ -892,7 +896,7 @@ TwoPhaseGetXidByVirtualXID(VirtualTransactionId vxid,
 
 /*
  * TwoPhaseGetDummyProcNumber
- *		Get the dummy proc number for prepared transaction specified by XID
+ *		Get the dummy proc number for prepared transaction
  *
  * Dummy proc numbers are similar to proc numbers of real backends.  They
  * start at MaxBackends, and are unique across all currently active real
@@ -900,24 +904,24 @@ TwoPhaseGetXidByVirtualXID(VirtualTransactionId vxid,
  * TwoPhaseStateLock will not be taken, so the caller had better hold it.
  */
 ProcNumber
-TwoPhaseGetDummyProcNumber(TransactionId xid, bool lock_held)
+TwoPhaseGetDummyProcNumber(FullTransactionId fxid, bool lock_held)
 {
-	GlobalTransaction gxact = TwoPhaseGetGXact(xid, lock_held);
+	GlobalTransaction gxact = TwoPhaseGetGXact(fxid, lock_held);
 
 	return gxact->pgprocno;
 }
 
 /*
  * TwoPhaseGetDummyProc
- *		Get the PGPROC that represents a prepared transaction specified by XID
+ *		Get the PGPROC that represents a prepared transaction
  *
  * If lock_held is set to true, TwoPhaseStateLock will not be taken, so the
  * caller had better hold it.
  */
 PGPROC *
-TwoPhaseGetDummyProc(TransactionId xid, bool lock_held)
+TwoPhaseGetDummyProc(FullTransactionId fxid, bool lock_held)
 {
-	GlobalTransaction gxact = TwoPhaseGetGXact(xid, lock_held);
+	GlobalTransaction gxact = TwoPhaseGetGXact(fxid, lock_held);
 
 	return GetPGProcByNumber(gxact->pgprocno);
 }
@@ -942,10 +946,8 @@ AdjustToFullTransactionId(TransactionId xid)
 }
 
 static inline int
-TwoPhaseFilePath(char *path, TransactionId xid)
+TwoPhaseFilePath(char *path, FullTransactionId fxid)
 {
-	FullTransactionId fxid = AdjustToFullTransactionId(xid);
-
 	return snprintf(path, MAXPGPATH, TWOPHASE_DIR "/%08X%08X",
 					EpochFromFullTransactionId(fxid),
 					XidFromFullTransactionId(fxid));
@@ -1049,7 +1051,7 @@ void
 StartPrepare(GlobalTransaction gxact)
 {
 	PGPROC	   *proc = GetPGProcByNumber(gxact->pgprocno);
-	TransactionId xid = gxact->xid;
+	TransactionId xid = XidFromFullTransactionId(gxact->fxid);
 	TwoPhaseFileHeader hdr;
 	TransactionId *children;
 	RelFileLocator *commitrels;
@@ -1281,10 +1283,11 @@ RegisterTwoPhaseRecord(TwoPhaseRmgrId rmid, uint16 info,
  * If it looks OK (has a valid magic number and CRC), return the palloc'd
  * contents of the file, issuing an error when finding corrupted data.  If
  * missing_ok is true, which indicates that missing files can be safely
- * ignored, then return NULL.  This state can be reached when doing recovery.
+ * ignored, then return NULL.  This state can be reached when doing recovery
+ * after discarding two-phase files from frozen epochs.
  */
 static char *
-ReadTwoPhaseFile(TransactionId xid, bool missing_ok)
+ReadTwoPhaseFile(FullTransactionId fxid, bool missing_ok)
 {
 	char		path[MAXPGPATH];
 	char	   *buf;
@@ -1296,7 +1299,7 @@ ReadTwoPhaseFile(TransactionId xid, bool missing_ok)
 				file_crc;
 	int			r;
 
-	TwoPhaseFilePath(path, xid);
+	TwoPhaseFilePath(path, fxid);
 
 	fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
 	if (fd < 0)
@@ -1461,6 +1464,7 @@ StandbyTransactionIdIsPrepared(TransactionId xid)
 	char	   *buf;
 	TwoPhaseFileHeader *hdr;
 	bool		result;
+	FullTransactionId fxid;
 
 	Assert(TransactionIdIsValid(xid));
 
@@ -1468,7 +1472,8 @@ StandbyTransactionIdIsPrepared(TransactionId xid)
 		return false;			/* nothing to do */
 
 	/* Read and validate file */
-	buf = ReadTwoPhaseFile(xid, true);
+	fxid = AdjustToFullTransactionId(xid);
+	buf = ReadTwoPhaseFile(fxid, true);
 	if (buf == NULL)
 		return false;
 
@@ -1488,6 +1493,7 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
 {
 	GlobalTransaction gxact;
 	PGPROC	   *proc;
+	FullTransactionId fxid;
 	TransactionId xid;
 	bool		ondisk;
 	char	   *buf;
@@ -1509,7 +1515,8 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
 	 */
 	gxact = LockGXact(gid, GetUserId());
 	proc = GetPGProcByNumber(gxact->pgprocno);
-	xid = gxact->xid;
+	fxid = gxact->fxid;
+	xid = XidFromFullTransactionId(fxid);
 
 	/*
 	 * Read and validate 2PC state data. State data will typically be stored
@@ -1517,7 +1524,7 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
 	 * to disk if for some reason they have lived for a long time.
 	 */
 	if (gxact->ondisk)
-		buf = ReadTwoPhaseFile(xid, false);
+		buf = ReadTwoPhaseFile(fxid, false);
 	else
 		XlogReadTwoPhaseData(gxact->prepare_start_lsn, &buf, NULL);
 
@@ -1636,11 +1643,11 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
 
 	/* And now do the callbacks */
 	if (isCommit)
-		ProcessRecords(bufptr, xid, twophase_postcommit_callbacks);
+		ProcessRecords(bufptr, fxid, twophase_postcommit_callbacks);
 	else
-		ProcessRecords(bufptr, xid, twophase_postabort_callbacks);
+		ProcessRecords(bufptr, fxid, twophase_postabort_callbacks);
 
-	PredicateLockTwoPhaseFinish(xid, isCommit);
+	PredicateLockTwoPhaseFinish(fxid, isCommit);
 
 	/*
 	 * Read this value while holding the two-phase lock, as the on-disk 2PC
@@ -1664,7 +1671,7 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
 	 * And now we can clean up any files we may have left.
 	 */
 	if (ondisk)
-		RemoveTwoPhaseFile(xid, true);
+		RemoveTwoPhaseFile(fxid, true);
 
 	MyLockedGxact = NULL;
 
@@ -1677,7 +1684,7 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
  * Scan 2PC state data in memory and call the indicated callbacks for each 2PC record.
  */
 static void
-ProcessRecords(char *bufptr, TransactionId xid,
+ProcessRecords(char *bufptr, FullTransactionId fxid,
 			   const TwoPhaseCallback callbacks[])
 {
 	for (;;)
@@ -1691,24 +1698,28 @@ ProcessRecords(char *bufptr, TransactionId xid,
 		bufptr += MAXALIGN(sizeof(TwoPhaseRecordOnDisk));
 
 		if (callbacks[record->rmid] != NULL)
-			callbacks[record->rmid] (xid, record->info, bufptr, record->len);
+			callbacks[record->rmid] (fxid, record->info, bufptr, record->len);
 
 		bufptr += MAXALIGN(record->len);
 	}
 }
 
 /*
- * Remove the 2PC file for the specified XID.
+ * Remove the 2PC file.
  *
  * If giveWarning is false, do not complain about file-not-present;
  * this is an expected case during WAL replay.
+ *
+ * This routine is used at early stages at recovery where future and
+ * past orphaned files are checked, hence the FullTransactionId to build
+ * a complete file name fit for the removal.
  */
 static void
-RemoveTwoPhaseFile(TransactionId xid, bool giveWarning)
+RemoveTwoPhaseFile(FullTransactionId fxid, bool giveWarning)
 {
 	char		path[MAXPGPATH];
 
-	TwoPhaseFilePath(path, xid);
+	TwoPhaseFilePath(path, fxid);
 	if (unlink(path))
 		if (errno != ENOENT || giveWarning)
 			ereport(WARNING,
@@ -1723,7 +1734,7 @@ RemoveTwoPhaseFile(TransactionId xid, bool giveWarning)
  * Note: content and len don't include CRC.
  */
 static void
-RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
+RecreateTwoPhaseFile(FullTransactionId fxid, void *content, int len)
 {
 	char		path[MAXPGPATH];
 	pg_crc32c	statefile_crc;
@@ -1734,7 +1745,7 @@ RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
 	COMP_CRC32C(statefile_crc, content, len);
 	FIN_CRC32C(statefile_crc);
 
-	TwoPhaseFilePath(path, xid);
+	TwoPhaseFilePath(path, fxid);
 
 	fd = OpenTransientFile(path,
 						   O_CREAT | O_TRUNC | O_WRONLY | PG_BINARY);
@@ -1846,7 +1857,7 @@ CheckPointTwoPhase(XLogRecPtr redo_horizon)
 			int			len;
 
 			XlogReadTwoPhaseData(gxact->prepare_start_lsn, &buf, &len);
-			RecreateTwoPhaseFile(gxact->xid, buf, len);
+			RecreateTwoPhaseFile(gxact->fxid, buf, len);
 			gxact->ondisk = true;
 			gxact->prepare_start_lsn = InvalidXLogRecPtr;
 			gxact->prepare_end_lsn = InvalidXLogRecPtr;
@@ -1897,19 +1908,17 @@ restoreTwoPhaseData(void)
 		if (strlen(clde->d_name) == 16 &&
 			strspn(clde->d_name, "0123456789ABCDEF") == 16)
 		{
-			TransactionId xid;
 			FullTransactionId fxid;
 			char	   *buf;
 
 			fxid = FullTransactionIdFromU64(strtou64(clde->d_name, NULL, 16));
-			xid = XidFromFullTransactionId(fxid);
 
-			buf = ProcessTwoPhaseBuffer(xid, InvalidXLogRecPtr,
+			buf = ProcessTwoPhaseBuffer(fxid, InvalidXLogRecPtr,
 										true, false, false);
 			if (buf == NULL)
 				continue;
 
-			PrepareRedoAdd(buf, InvalidXLogRecPtr,
+			PrepareRedoAdd(fxid, buf, InvalidXLogRecPtr,
 						   InvalidXLogRecPtr, InvalidRepOriginId);
 		}
 	}
@@ -1968,9 +1977,7 @@ PrescanPreparedTransactions(TransactionId **xids_p, int *nxids_p)
 
 		Assert(gxact->inredo);
 
-		xid = gxact->xid;
-
-		buf = ProcessTwoPhaseBuffer(xid,
+		buf = ProcessTwoPhaseBuffer(gxact->fxid,
 									gxact->prepare_start_lsn,
 									gxact->ondisk, false, true);
 
@@ -1981,6 +1988,7 @@ PrescanPreparedTransactions(TransactionId **xids_p, int *nxids_p)
 		 * OK, we think this file is valid.  Incorporate xid into the
 		 * running-minimum result.
 		 */
+		xid = XidFromFullTransactionId(gxact->fxid);
 		if (TransactionIdPrecedes(xid, result))
 			result = xid;
 
@@ -2036,15 +2044,12 @@ StandbyRecoverPreparedTransactions(void)
 	LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
 	for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
 	{
-		TransactionId xid;
 		char	   *buf;
 		GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
 
 		Assert(gxact->inredo);
 
-		xid = gxact->xid;
-
-		buf = ProcessTwoPhaseBuffer(xid,
+		buf = ProcessTwoPhaseBuffer(gxact->fxid,
 									gxact->prepare_start_lsn,
 									gxact->ondisk, true, false);
 		if (buf != NULL)
@@ -2077,16 +2082,14 @@ RecoverPreparedTransactions(void)
 	LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
 	for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
 	{
-		TransactionId xid;
 		char	   *buf;
 		GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
+		FullTransactionId fxid = gxact->fxid;
 		char	   *bufptr;
 		TwoPhaseFileHeader *hdr;
 		TransactionId *subxids;
 		const char *gid;
 
-		xid = gxact->xid;
-
 		/*
 		 * Reconstruct subtrans state for the transaction --- needed because
 		 * pg_subtrans is not preserved over a restart.  Note that we are
@@ -2096,17 +2099,20 @@ RecoverPreparedTransactions(void)
 		 * SubTransSetParent has been set before, if the prepared transaction
 		 * generated xid assignment records.
 		 */
-		buf = ProcessTwoPhaseBuffer(xid,
+		buf = ProcessTwoPhaseBuffer(gxact->fxid,
 									gxact->prepare_start_lsn,
 									gxact->ondisk, true, false);
 		if (buf == NULL)
 			continue;
 
 		ereport(LOG,
-				(errmsg("recovering prepared transaction %u from shared memory", xid)));
+				(errmsg("recovering prepared transaction %u of epoch %u from shared memory",
+						XidFromFullTransactionId(gxact->fxid),
+						EpochFromFullTransactionId(gxact->fxid))));
 
 		hdr = (TwoPhaseFileHeader *) buf;
-		Assert(TransactionIdEquals(hdr->xid, xid));
+		Assert(TransactionIdEquals(hdr->xid,
+								   XidFromFullTransactionId(gxact->fxid)));
 		bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
 		gid = (const char *) bufptr;
 		bufptr += MAXALIGN(hdr->gidlen);
@@ -2122,7 +2128,7 @@ RecoverPreparedTransactions(void)
 		 * Recreate its GXACT and dummy PGPROC. But, check whether it was
 		 * added in redo and already has a shmem entry for it.
 		 */
-		MarkAsPreparingGuts(gxact, xid, gid,
+		MarkAsPreparingGuts(gxact, gxact->fxid, gid,
 							hdr->prepared_at,
 							hdr->owner, hdr->database);
 
@@ -2137,7 +2143,7 @@ RecoverPreparedTransactions(void)
 		/*
 		 * Recover other state (notably locks) using resource managers.
 		 */
-		ProcessRecords(bufptr, xid, twophase_recover_callbacks);
+		ProcessRecords(bufptr, fxid, twophase_recover_callbacks);
 
 		/*
 		 * Release locks held by the standby process after we process each
@@ -2145,7 +2151,7 @@ RecoverPreparedTransactions(void)
 		 * additional locks at any one time.
 		 */
 		if (InHotStandby)
-			StandbyReleaseLockTree(xid, hdr->nsubxacts, subxids);
+			StandbyReleaseLockTree(hdr->xid, hdr->nsubxacts, subxids);
 
 		/*
 		 * We're done with recovering this transaction. Clear MyLockedGxact,
@@ -2164,7 +2170,7 @@ RecoverPreparedTransactions(void)
 /*
  * ProcessTwoPhaseBuffer
  *
- * Given a transaction id, read it either from disk or read it directly
+ * Given a FullTransactionId, read it either from disk or read it directly
  * via shmem xlog record pointer using the provided "prepare_start_lsn".
  *
  * If setParent is true, set up subtransaction parent linkages.
@@ -2173,13 +2179,12 @@ RecoverPreparedTransactions(void)
  * value scanned.
  */
 static char *
-ProcessTwoPhaseBuffer(TransactionId xid,
+ProcessTwoPhaseBuffer(FullTransactionId fxid,
 					  XLogRecPtr prepare_start_lsn,
 					  bool fromdisk,
 					  bool setParent, bool setNextXid)
 {
 	FullTransactionId nextXid = TransamVariables->nextXid;
-	TransactionId origNextXid = XidFromFullTransactionId(nextXid);
 	TransactionId *subxids;
 	char	   *buf;
 	TwoPhaseFileHeader *hdr;
@@ -2191,41 +2196,46 @@ ProcessTwoPhaseBuffer(TransactionId xid,
 		Assert(prepare_start_lsn != InvalidXLogRecPtr);
 
 	/* Already processed? */
-	if (TransactionIdDidCommit(xid) || TransactionIdDidAbort(xid))
+	if (TransactionIdDidCommit(XidFromFullTransactionId(fxid)) ||
+		TransactionIdDidAbort(XidFromFullTransactionId(fxid)))
 	{
 		if (fromdisk)
 		{
 			ereport(WARNING,
-					(errmsg("removing stale two-phase state file for transaction %u",
-							xid)));
-			RemoveTwoPhaseFile(xid, true);
+					(errmsg("removing stale two-phase state file for transaction %u of epoch %u",
+							XidFromFullTransactionId(fxid),
+							EpochFromFullTransactionId(fxid))));
+			RemoveTwoPhaseFile(fxid, true);
 		}
 		else
 		{
 			ereport(WARNING,
-					(errmsg("removing stale two-phase state from memory for transaction %u",
-							xid)));
-			PrepareRedoRemove(xid, true);
+					(errmsg("removing stale two-phase state from memory for transaction %u of epoch %u",
+							XidFromFullTransactionId(fxid),
+							EpochFromFullTransactionId(fxid))));
+			PrepareRedoRemoveFull(fxid, true);
 		}
 		return NULL;
 	}
 
 	/* Reject XID if too new */
-	if (TransactionIdFollowsOrEquals(xid, origNextXid))
+	if (FullTransactionIdFollowsOrEquals(fxid, nextXid))
 	{
 		if (fromdisk)
 		{
 			ereport(WARNING,
-					(errmsg("removing future two-phase state file for transaction %u",
-							xid)));
-			RemoveTwoPhaseFile(xid, true);
+					(errmsg("removing future two-phase state file for transaction %u of epoch %u",
+							XidFromFullTransactionId(fxid),
+							EpochFromFullTransactionId(fxid))));
+			RemoveTwoPhaseFile(fxid, true);
 		}
 		else
 		{
 			ereport(WARNING,
-					(errmsg("removing future two-phase state from memory for transaction %u",
-							xid)));
-			PrepareRedoRemove(xid, true);
+					(errmsg("removing future two-phase state from memory for transaction %u of epoch %u",
+							XidFromFullTransactionId(fxid),
+							EpochFromFullTransactionId(fxid))));
+			PrepareRedoRemoveFull(fxid, true);
 		}
 		return NULL;
 	}
@@ -2233,7 +2243,7 @@ ProcessTwoPhaseBuffer(TransactionId xid,
 	if (fromdisk)
 	{
 		/* Read and validate file */
-		buf = ReadTwoPhaseFile(xid, false);
+		buf = ReadTwoPhaseFile(fxid, false);
 	}
 	else
 	{
@@ -2243,18 +2253,20 @@ ProcessTwoPhaseBuffer(TransactionId xid,
 
 	/* Deconstruct header */
 	hdr = (TwoPhaseFileHeader *) buf;
-	if (!TransactionIdEquals(hdr->xid, xid))
+	if (!TransactionIdEquals(hdr->xid, XidFromFullTransactionId(fxid)))
 	{
 		if (fromdisk)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("corrupted two-phase state file for transaction %u",
-							xid)));
+					 errmsg("corrupted two-phase state file for transaction %u of epoch %u",
+							XidFromFullTransactionId(fxid),
+							EpochFromFullTransactionId(fxid))));
 		else
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg("corrupted two-phase state in memory for transaction %u",
-							xid)));
+					 errmsg("corrupted two-phase state in memory for transaction %u of epoch %u",
+							XidFromFullTransactionId(fxid),
+							EpochFromFullTransactionId(fxid))));
 	}
 
 	/*
@@ -2268,14 +2280,14 @@ ProcessTwoPhaseBuffer(TransactionId xid,
 	{
 		TransactionId subxid = subxids[i];
 
-		Assert(TransactionIdFollows(subxid, xid));
+		Assert(TransactionIdFollows(subxid, XidFromFullTransactionId(fxid)));
 
 		/* update nextXid if needed */
 		if (setNextXid)
 			AdvanceNextFullTransactionIdPastXid(subxid);
 
 		if (setParent)
-			SubTransSetParent(subxid, xid);
+			SubTransSetParent(subxid, XidFromFullTransactionId(fxid));
 	}
 
 	return buf;
@@ -2466,8 +2478,9 @@ RecordTransactionAbortPrepared(TransactionId xid,
  * data, the entry is marked as located on disk.
  */
 void
-PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
-			   XLogRecPtr end_lsn, RepOriginId origin_id)
+PrepareRedoAdd(FullTransactionId fxid, char *buf,
+			   XLogRecPtr start_lsn, XLogRecPtr end_lsn,
+			   RepOriginId origin_id)
 {
 	TwoPhaseFileHeader *hdr = (TwoPhaseFileHeader *) buf;
 	char	   *bufptr;
@@ -2477,6 +2490,13 @@ PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
 	Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
 	Assert(RecoveryInProgress());
 
+	if (!FullTransactionIdIsValid(fxid))
+	{
+		Assert(InRecovery);
+		fxid = FullTransactionIdFromAllowableAt(TransamVariables->nextXid,
+												hdr->xid);
+	}
+
 	bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
 	gid = (const char *) bufptr;
 
@@ -2505,7 +2525,8 @@ PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
 	{
 		char		path[MAXPGPATH];
 
-		TwoPhaseFilePath(path, hdr->xid);
+		Assert(InRecovery);
+		TwoPhaseFilePath(path, fxid);
 
 		if (access(path, F_OK) == 0)
 		{
@@ -2536,7 +2557,7 @@ PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
 	gxact->prepared_at = hdr->prepared_at;
 	gxact->prepare_start_lsn = start_lsn;
 	gxact->prepare_end_lsn = end_lsn;
-	gxact->xid = hdr->xid;
+	gxact->fxid = fxid;
 	gxact->owner = hdr->owner;
 	gxact->locking_backend = INVALID_PROC_NUMBER;
 	gxact->valid = false;
@@ -2555,11 +2576,13 @@ PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
 						   false /* backward */ , false /* WAL */ );
 	}
 
-	elog(DEBUG2, "added 2PC data in shared memory for transaction %u", gxact->xid);
+	elog(DEBUG2, "added 2PC data in shared memory for transaction %u of epoch %u",
+		 XidFromFullTransactionId(gxact->fxid),
+		 EpochFromFullTransactionId(gxact->fxid));
 }
 
 /*
- * PrepareRedoRemove
+ * PrepareRedoRemoveFull
  *
  * Remove the corresponding gxact entry from TwoPhaseState. Also remove
  * the 2PC file if a prepared transaction was saved via an earlier checkpoint.
@@ -2567,8 +2590,8 @@ PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
  * Caller must hold TwoPhaseStateLock in exclusive mode, because TwoPhaseState
  * is updated.
  */
-void
-PrepareRedoRemove(TransactionId xid, bool giveWarning)
+static void
+PrepareRedoRemoveFull(FullTransactionId fxid, bool giveWarning)
 {
 	GlobalTransaction gxact = NULL;
 	int			i;
@@ -2581,7 +2604,7 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)
 	{
 		gxact = TwoPhaseState->prepXacts[i];
 
-		if (gxact->xid == xid)
+		if (FullTransactionIdEquals(gxact->fxid, fxid))
 		{
 			Assert(gxact->inredo);
 			found = true;
@@ -2598,13 +2621,29 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)
 	/*
 	 * And now we can clean up any files we may have left.
 	 */
-	elog(DEBUG2, "removing 2PC data for transaction %u", xid);
+	elog(DEBUG2, "removing 2PC data for transaction %u of epoch %u ",
+		 XidFromFullTransactionId(fxid),
+		 EpochFromFullTransactionId(fxid));
+
 	if (gxact->ondisk)
-		RemoveTwoPhaseFile(xid, giveWarning);
+		RemoveTwoPhaseFile(fxid, giveWarning);
+
 	RemoveGXact(gxact);
 }
 
 /*
+ * Wrapper of PrepareRedoRemoveFull(), for TransactionIds.
+ */
+void
+PrepareRedoRemove(TransactionId xid, bool giveWarning)
+{
+	FullTransactionId fxid =
+		FullTransactionIdFromAllowableAt(TransamVariables->nextXid, xid);
+
+	PrepareRedoRemoveFull(fxid, giveWarning);
+}
+
+/*
  * LookupGXact
  *		Check if the prepared transaction with the given GID, lsn and timestamp
  *		exists.
@@ -2648,7 +2687,7 @@ LookupGXact(const char *gid, XLogRecPtr prepare_end_lsn,
 			 * between publisher and subscriber.
 			 */
 			if (gxact->ondisk)
-				buf = ReadTwoPhaseFile(gxact->xid, false);
+				buf = ReadTwoPhaseFile(gxact->fxid, false);
 			else
 			{
 				Assert(gxact->prepare_start_lsn);
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index b885513f765..41601fcb280 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2515,7 +2515,7 @@ static void
 PrepareTransaction(void)
 {
 	TransactionState s = CurrentTransactionState;
-	TransactionId xid = GetCurrentTransactionId();
+	FullTransactionId fxid = GetCurrentFullTransactionId();
 	GlobalTransaction gxact;
 	TimestampTz prepared_at;
 
@@ -2644,7 +2644,7 @@ PrepareTransaction(void)
 	 * Reserve the GID for this transaction. This could fail if the requested
 	 * GID is invalid or already in use.
 	 */
-	gxact = MarkAsPreparing(xid, prepareGID, prepared_at,
+	gxact = MarkAsPreparing(fxid, prepareGID, prepared_at,
 							GetUserId(), MyDatabaseId);
 	prepareGID = NULL;
 
@@ -2694,7 +2694,7 @@ PrepareTransaction(void)
 	 * ProcArrayClearTransaction().  Otherwise, a GetLockConflicts() would
 	 * conclude "xact already committed or aborted" for our locks.
 	 */
-	PostPrepare_Locks(xid);
+	PostPrepare_Locks(fxid);
 
 	/*
 	 * Let others know about no transaction in progress by me.  This has to be
@@ -2738,9 +2738,9 @@ PrepareTransaction(void)
 
 	PostPrepare_smgr();
 
-	PostPrepare_MultiXact(xid);
+	PostPrepare_MultiXact(fxid);
 
-	PostPrepare_PredicateLocks(xid);
+	PostPrepare_PredicateLocks(fxid);
 
 	ResourceOwnerRelease(TopTransactionResourceOwner,
 						 RESOURCE_RELEASE_LOCKS,
@@ -6420,7 +6420,8 @@ xact_redo(XLogReaderState *record)
 		 * gxact entry.
 		 */
 		LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
-		PrepareRedoAdd(XLogRecGetData(record),
+		PrepareRedoAdd(InvalidFullTransactionId,
+					   XLogRecGetData(record),
 					   record->ReadRecPtr,
 					   record->EndRecPtr,
 					   XLogRecGetOrigin(record));
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 2776ceb295b..62f3471448e 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -3539,9 +3539,9 @@ AtPrepare_Locks(void)
  * but that probably costs more cycles.
  */
 void
-PostPrepare_Locks(TransactionId xid)
+PostPrepare_Locks(FullTransactionId fxid)
 {
-	PGPROC	   *newproc = TwoPhaseGetDummyProc(xid, false);
+	PGPROC	   *newproc = TwoPhaseGetDummyProc(fxid, false);
 	HASH_SEQ_STATUS status;
 	LOCALLOCK  *locallock;
 	LOCK	   *lock;
@@ -4324,11 +4324,11 @@ DumpAllLocks(void)
  * and PANIC anyway.
  */
 void
-lock_twophase_recover(TransactionId xid, uint16 info,
+lock_twophase_recover(FullTransactionId fxid, uint16 info,
 					  void *recdata, uint32 len)
 {
 	TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
-	PGPROC	   *proc = TwoPhaseGetDummyProc(xid, false);
+	PGPROC	   *proc = TwoPhaseGetDummyProc(fxid, false);
 	LOCKTAG    *locktag;
 	LOCKMODE	lockmode;
 	LOCKMETHODID lockmethodid;
@@ -4505,7 +4505,7 @@ lock_twophase_recover(TransactionId xid, uint16 info,
  * starting up into hot standby mode.
  */
 void
-lock_twophase_standby_recover(TransactionId xid, uint16 info,
+lock_twophase_standby_recover(FullTransactionId fxid, uint16 info,
 							  void *recdata, uint32 len)
 {
 	TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
@@ -4524,7 +4524,7 @@ lock_twophase_standby_recover(TransactionId xid, uint16 info,
 	if (lockmode == AccessExclusiveLock &&
 		locktag->locktag_type == LOCKTAG_RELATION)
 	{
-		StandbyAcquireAccessExclusiveLock(xid,
+		StandbyAcquireAccessExclusiveLock(XidFromFullTransactionId(fxid),
 										  locktag->locktag_field1 /* dboid */ ,
 										  locktag->locktag_field2 /* reloid */ );
 	}
@@ -4537,11 +4537,11 @@ lock_twophase_standby_recover(TransactionId xid, uint16 info,
  * Find and release the lock indicated by the 2PC record.
  */
 void
-lock_twophase_postcommit(TransactionId xid, uint16 info,
+lock_twophase_postcommit(FullTransactionId fxid, uint16 info,
 						 void *recdata, uint32 len)
 {
 	TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
-	PGPROC	   *proc = TwoPhaseGetDummyProc(xid, true);
+	PGPROC	   *proc = TwoPhaseGetDummyProc(fxid, true);
 	LOCKTAG    *locktag;
 	LOCKMETHODID lockmethodid;
 	LockMethod	lockMethodTable;
@@ -4563,10 +4563,10 @@ lock_twophase_postcommit(TransactionId xid, uint16 info,
  * This is actually just the same as the COMMIT case.
  */
 void
-lock_twophase_postabort(TransactionId xid, uint16 info,
+lock_twophase_postabort(FullTransactionId fxid, uint16 info,
 						void *recdata, uint32 len)
 {
-	lock_twophase_postcommit(xid, info, recdata, len);
+	lock_twophase_postcommit(fxid, info, recdata, len);
 }
 
 /*
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index d82114ffca1..c07fb588355 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -191,7 +191,7 @@
  *		AtPrepare_PredicateLocks(void);
  *		PostPrepare_PredicateLocks(TransactionId xid);
  *		PredicateLockTwoPhaseFinish(TransactionId xid, bool isCommit);
- *		predicatelock_twophase_recover(TransactionId xid, uint16 info,
+ *		predicatelock_twophase_recover(FullTransactionId fxid, uint16 info,
  *									   void *recdata, uint32 len);
  */
 
@@ -4856,7 +4856,7 @@ AtPrepare_PredicateLocks(void)
  *		anyway. We only need to clean up our local state.
  */
 void
-PostPrepare_PredicateLocks(TransactionId xid)
+PostPrepare_PredicateLocks(FullTransactionId fxid)
 {
 	if (MySerializableXact == InvalidSerializableXact)
 		return;
@@ -4879,12 +4879,12 @@ PostPrepare_PredicateLocks(TransactionId xid)
  *		commits or aborts.
  */
 void
-PredicateLockTwoPhaseFinish(TransactionId xid, bool isCommit)
+PredicateLockTwoPhaseFinish(FullTransactionId fxid, bool isCommit)
 {
 	SERIALIZABLEXID *sxid;
 	SERIALIZABLEXIDTAG sxidtag;
 
-	sxidtag.xid = xid;
+	sxidtag.xid = XidFromFullTransactionId(fxid);
 
 	LWLockAcquire(SerializableXactHashLock, LW_SHARED);
 	sxid = (SERIALIZABLEXID *)
@@ -4906,10 +4906,11 @@ PredicateLockTwoPhaseFinish(TransactionId xid, bool isCommit)
  * Re-acquire a predicate lock belonging to a transaction that was prepared.
  */
 void
-predicatelock_twophase_recover(TransactionId xid, uint16 info,
+predicatelock_twophase_recover(FullTransactionId fxid, uint16 info,
 							   void *recdata, uint32 len)
 {
 	TwoPhasePredicateRecord *record;
+	TransactionId xid = XidFromFullTransactionId(fxid);
 
 	Assert(len == sizeof(TwoPhasePredicateRecord));
 
diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c
index 28587e2916b..69df741cbf6 100644
--- a/src/backend/utils/activity/pgstat_relation.c
+++ b/src/backend/utils/activity/pgstat_relation.c
@@ -744,7 +744,7 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
  * Load the saved counts into our local pgstats state.
  */
 void
-pgstat_twophase_postcommit(TransactionId xid, uint16 info,
+pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info,
 						   void *recdata, uint32 len)
 {
 	TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
@@ -780,7 +780,7 @@ pgstat_twophase_postcommit(TransactionId xid, uint16 info,
  * as aborted.
  */
 void
-pgstat_twophase_postabort(TransactionId xid, uint16 info,
+pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
 						  void *recdata, uint32 len)
 {
 	TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
diff --git a/src/include/access/multixact.h b/src/include/access/multixact.h
index 4e6b0eec2ff..b876e98f46e 100644
--- a/src/include/access/multixact.h
+++ b/src/include/access/multixact.h
@@ -11,6 +11,7 @@
 #ifndef MULTIXACT_H
 #define MULTIXACT_H
 
+#include "access/transam.h"
 #include "access/xlogreader.h"
 #include "lib/stringinfo.h"
 #include "storage/sync.h"
@@ -119,7 +120,7 @@ extern int	multixactmemberssyncfiletag(const FileTag *ftag, char *path);
 
 extern void AtEOXact_MultiXact(void);
 extern void AtPrepare_MultiXact(void);
-extern void PostPrepare_MultiXact(TransactionId xid);
+extern void PostPrepare_MultiXact(FullTransactionId fxid);
 
 extern Size MultiXactShmemSize(void);
 extern void MultiXactShmemInit(void);
@@ -145,11 +146,11 @@ extern void MultiXactAdvanceNextMXact(MultiXactId minMulti,
 extern void MultiXactAdvanceOldest(MultiXactId oldestMulti, Oid oldestMultiDB);
 extern int	MultiXactMemberFreezeThreshold(void);
 
-extern void multixact_twophase_recover(TransactionId xid, uint16 info,
+extern void multixact_twophase_recover(FullTransactionId fxid, uint16 info,
 									   void *recdata, uint32 len);
-extern void multixact_twophase_postcommit(TransactionId xid, uint16 info,
+extern void multixact_twophase_postcommit(FullTransactionId fxid, uint16 info,
 										  void *recdata, uint32 len);
-extern void multixact_twophase_postabort(TransactionId xid, uint16 info,
+extern void multixact_twophase_postabort(FullTransactionId fxid, uint16 info,
 										 void *recdata, uint32 len);
 
 extern void multixact_redo(XLogReaderState *record);
diff --git a/src/include/access/twophase.h b/src/include/access/twophase.h
index 9fa82355033..509bdad9a5d 100644
--- a/src/include/access/twophase.h
+++ b/src/include/access/twophase.h
@@ -36,10 +36,10 @@ extern void PostPrepare_Twophase(void);
 
 extern TransactionId TwoPhaseGetXidByVirtualXID(VirtualTransactionId vxid,
 												bool *have_more);
-extern PGPROC *TwoPhaseGetDummyProc(TransactionId xid, bool lock_held);
-extern int	TwoPhaseGetDummyProcNumber(TransactionId xid, bool lock_held);
+extern PGPROC *TwoPhaseGetDummyProc(FullTransactionId fxid, bool lock_held);
+extern int	TwoPhaseGetDummyProcNumber(FullTransactionId fxid, bool lock_held);
 
-extern GlobalTransaction MarkAsPreparing(TransactionId xid, const char *gid,
+extern GlobalTransaction MarkAsPreparing(FullTransactionId fxid, const char *gid,
 										 TimestampTz prepared_at,
 										 Oid owner, Oid databaseid);
 
@@ -56,8 +56,9 @@ extern void CheckPointTwoPhase(XLogRecPtr redo_horizon);
 
 extern void FinishPreparedTransaction(const char *gid, bool isCommit);
 
-extern void PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
-						   XLogRecPtr end_lsn, RepOriginId origin_id);
+extern void PrepareRedoAdd(FullTransactionId fxid, char *buf,
+						   XLogRecPtr start_lsn, XLogRecPtr end_lsn,
+						   RepOriginId origin_id);
 extern void PrepareRedoRemove(TransactionId xid, bool giveWarning);
 extern void restoreTwoPhaseData(void);
 extern bool LookupGXact(const char *gid, XLogRecPtr prepare_end_lsn,
diff --git a/src/include/access/twophase_rmgr.h b/src/include/access/twophase_rmgr.h
index 3ed154bb231..8f576402e36 100644
--- a/src/include/access/twophase_rmgr.h
+++ b/src/include/access/twophase_rmgr.h
@@ -14,7 +14,9 @@
 #ifndef TWOPHASE_RMGR_H
 #define TWOPHASE_RMGR_H
 
-typedef void (*TwoPhaseCallback) (TransactionId xid, uint16 info,
+#include "access/transam.h"
+
+typedef void (*TwoPhaseCallback) (FullTransactionId fxid, uint16 info,
 								  void *recdata, uint32 len);
 typedef uint8 TwoPhaseRmgrId;
 
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 378f2f2c2ba..202bd2d5ace 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -718,9 +718,9 @@ extern void pgstat_count_heap_delete(Relation rel);
 extern void pgstat_count_truncate(Relation rel);
 extern void pgstat_update_heap_dead_tuples(Relation rel, int delta);
 
-extern void pgstat_twophase_postcommit(TransactionId xid, uint16 info,
+extern void pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info,
 									   void *recdata, uint32 len);
-extern void pgstat_twophase_postabort(TransactionId xid, uint16 info,
+extern void pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
 									  void *recdata, uint32 len);
 
 extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry(Oid relid);
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h
index 4862b80eec3..826cf28fdbd 100644
--- a/src/include/storage/lock.h
+++ b/src/include/storage/lock.h
@@ -18,6 +18,7 @@
 #error "lock.h may not be included from frontend code"
 #endif
 
+#include "access/transam.h"
 #include "lib/ilist.h"
 #include "storage/lockdefs.h"
 #include "storage/lwlock.h"
@@ -581,7 +582,7 @@ extern bool LockHasWaiters(const LOCKTAG *locktag,
 extern VirtualTransactionId *GetLockConflicts(const LOCKTAG *locktag,
 											  LOCKMODE lockmode, int *countp);
 extern void AtPrepare_Locks(void);
-extern void PostPrepare_Locks(TransactionId xid);
+extern void PostPrepare_Locks(FullTransactionId fxid);
 extern bool LockCheckConflicts(LockMethod lockMethodTable,
 							   LOCKMODE lockmode,
 							   LOCK *lock, PROCLOCK *proclock);
@@ -597,13 +598,13 @@ extern BlockedProcsData *GetBlockerStatusData(int blocked_pid);
 extern xl_standby_lock *GetRunningTransactionLocks(int *nlocks);
 extern const char *GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode);
 
-extern void lock_twophase_recover(TransactionId xid, uint16 info,
+extern void lock_twophase_recover(FullTransactionId fxid, uint16 info,
 								  void *recdata, uint32 len);
-extern void lock_twophase_postcommit(TransactionId xid, uint16 info,
+extern void lock_twophase_postcommit(FullTransactionId fxid, uint16 info,
 									 void *recdata, uint32 len);
-extern void lock_twophase_postabort(TransactionId xid, uint16 info,
+extern void lock_twophase_postabort(FullTransactionId fxid, uint16 info,
 									void *recdata, uint32 len);
-extern void lock_twophase_standby_recover(TransactionId xid, uint16 info,
+extern void lock_twophase_standby_recover(FullTransactionId fxid, uint16 info,
 										  void *recdata, uint32 len);
 
 extern DeadLockState DeadLockCheck(PGPROC *proc);
diff --git a/src/include/storage/predicate.h b/src/include/storage/predicate.h
index 267d5d90e94..c1e3a4d9f64 100644
--- a/src/include/storage/predicate.h
+++ b/src/include/storage/predicate.h
@@ -72,9 +72,9 @@ extern void PreCommit_CheckForSerializationFailure(void);
 
 /* two-phase commit support */
 extern void AtPrepare_PredicateLocks(void);
-extern void PostPrepare_PredicateLocks(TransactionId xid);
-extern void PredicateLockTwoPhaseFinish(TransactionId xid, bool isCommit);
-extern void predicatelock_twophase_recover(TransactionId xid, uint16 info,
+extern void PostPrepare_PredicateLocks(FullTransactionId fxid);
+extern void PredicateLockTwoPhaseFinish(FullTransactionId xid, bool isCommit);
+extern void predicatelock_twophase_recover(FullTransactionId fxid, uint16 info,
 										   void *recdata, uint32 len);
 
 /* parallel query support */