3 files changed, 22 insertions, 17 deletions

diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index a4599e96610..65aa8841f7c 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -295,7 +295,7 @@ TransactionIdSetPageStatus(TransactionId xid, int nsubxids,
 	 */
 	if (all_xact_same_page && xid == MyProc->xid &&
 		nsubxids <= THRESHOLD_SUBTRANS_CLOG_OPT &&
-		nsubxids == MyPgXact->nxids &&
+		nsubxids == MyProc->subxidStatus.count &&
 		memcmp(subxids, MyProc->subxids.xids,
 			   nsubxids * sizeof(TransactionId)) == 0)
 	{
@@ -510,16 +510,15 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 	while (nextidx != INVALID_PGPROCNO)
 	{
 		PGPROC	   *proc = &ProcGlobal->allProcs[nextidx];
-		PGXACT	   *pgxact = &ProcGlobal->allPgXact[nextidx];
 
 		/*
 		 * Transactions with more than THRESHOLD_SUBTRANS_CLOG_OPT sub-XIDs
 		 * should not use group XID status update mechanism.
 		 */
-		Assert(pgxact->nxids <= THRESHOLD_SUBTRANS_CLOG_OPT);
+		Assert(proc->subxidStatus.count <= THRESHOLD_SUBTRANS_CLOG_OPT);
 
 		TransactionIdSetPageStatusInternal(proc->clogGroupMemberXid,
-										   pgxact->nxids,
+										   proc->subxidStatus.count,
 										   proc->subxids.xids,
 										   proc->clogGroupMemberXidStatus,
 										   proc->clogGroupMemberLsn,
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 744b8a7f393..ef4f9981e35 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -21,9 +21,9 @@
  *		GIDs and aborts the transaction if there already is a global
  *		transaction in prepared state with the same GID.
  *
- *		A global transaction (gxact) also has dummy PGXACT and PGPROC; this is
- *		what keeps the XID considered running by TransactionIdIsInProgress.
- *		It is also convenient as a PGPROC to hook the gxact's locks to.
+ *		A global transaction (gxact) also has dummy PGPROC; this is what keeps
+ *		the XID considered running by TransactionIdIsInProgress.  It is also
+ *		convenient as a PGPROC to hook the gxact's locks to.
  *
  *		Information to recover prepared transactions in case of crash is
  *		now stored in WAL for the common case. In some cases there will be
@@ -447,14 +447,12 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
 					TimestampTz prepared_at, Oid owner, Oid databaseid)
 {
 	PGPROC	   *proc;
-	PGXACT	   *pgxact;
 	int			i;
 
 	Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
 
 	Assert(gxact != NULL);
 	proc = &ProcGlobal->allProcs[gxact->pgprocno];
-	pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
 
 	/* Initialize the PGPROC entry */
 	MemSet(proc, 0, sizeof(PGPROC));
@@ -480,8 +478,8 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
 	for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
 		SHMQueueInit(&(proc->myProcLocks[i]));
 	/* subxid data must be filled later by GXactLoadSubxactData */
-	pgxact->overflowed = false;
-	pgxact->nxids = 0;
+	proc->subxidStatus.overflowed = false;
+	proc->subxidStatus.count = 0;
 
 	gxact->prepared_at = prepared_at;
 	gxact->xid = xid;
@@ -510,19 +508,18 @@ GXactLoadSubxactData(GlobalTransaction gxact, int nsubxacts,
 					 TransactionId *children)
 {
 	PGPROC	   *proc = &ProcGlobal->allProcs[gxact->pgprocno];
-	PGXACT	   *pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
 
 	/* We need no extra lock since the GXACT isn't valid yet */
 	if (nsubxacts > PGPROC_MAX_CACHED_SUBXIDS)
 	{
-		pgxact->overflowed = true;
+		proc->subxidStatus.overflowed = true;
 		nsubxacts = PGPROC_MAX_CACHED_SUBXIDS;
 	}
 	if (nsubxacts > 0)
 	{
 		memcpy(proc->subxids.xids, children,
 			   nsubxacts * sizeof(TransactionId));
-		pgxact->nxids = nsubxacts;
+		proc->subxidStatus.count = nsubxacts;
 	}
 }
 
diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 4c91b343ecd..2d2b05be36c 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -222,22 +222,31 @@ GetNewTransactionId(bool isSubXact)
 	 */
 	if (!isSubXact)
 	{
+		Assert(ProcGlobal->subxidStates[MyProc->pgxactoff].count == 0);
+		Assert(!ProcGlobal->subxidStates[MyProc->pgxactoff].overflowed);
+		Assert(MyProc->subxidStatus.count == 0);
+		Assert(!MyProc->subxidStatus.overflowed);
+
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
 	}
 	else
 	{
-		int			nxids = MyPgXact->nxids;
+		XidCacheStatus *substat = &ProcGlobal->subxidStates[MyProc->pgxactoff];
+		int			nxids = MyProc->subxidStatus.count;
+
+		Assert(substat->count == MyProc->subxidStatus.count);
+		Assert(substat->overflowed == MyProc->subxidStatus.overflowed);
 
 		if (nxids < PGPROC_MAX_CACHED_SUBXIDS)
 		{
 			MyProc->subxids.xids[nxids] = xid;
 			pg_write_barrier();
-			MyPgXact->nxids = nxids + 1;
+			MyProc->subxidStatus.count = substat->count = nxids + 1;
 		}
 		else
-			MyPgXact->overflowed = true;
+			MyProc->subxidStatus.overflowed = substat->overflowed = true;
 	}
 
 	LWLockRelease(XidGenLock);