diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
new file mode 100644
index 2812681..f552800
*** a/src/backend/access/transam/twophase.c
--- b/src/backend/access/transam/twophase.c
*************** RecordTransactionCommitPrepared(Transact
*** 1977,2014 ****
  	xlrec.xid = xid;
  	xlrec.crec.xact_time = GetCurrentTimestamp();
  	xlrec.crec.xinfo = initfileinval ? XACT_COMPLETION_UPDATE_RELCACHE_FILE : 0;
- 	xlrec.crec.nmsgs = 0;
- 	xlrec.crec.nrels = nrels;
- 	xlrec.crec.nsubxacts = nchildren;
- 	xlrec.crec.nmsgs = ninvalmsgs;
- 
  	rdata[0].data = (char *) (&xlrec);
  	rdata[0].len = MinSizeOfXactCommitPrepared;
  	rdata[0].buffer = InvalidBuffer;
  	/* dump rels to delete */
  	if (nrels > 0)
  	{
  		rdata[0].next = &(rdata[1]);
! 		rdata[1].data = (char *) rels;
! 		rdata[1].len = nrels * sizeof(RelFileNode);
  		rdata[1].buffer = InvalidBuffer;
  		lastrdata = 1;
  	}
  	/* dump committed child Xids */
  	if (nchildren > 0)
  	{
  		rdata[lastrdata].next = &(rdata[2]);
! 		rdata[2].data = (char *) children;
! 		rdata[2].len = nchildren * sizeof(TransactionId);
  		rdata[2].buffer = InvalidBuffer;
  		lastrdata = 2;
  	}
! 	/* dump cache invalidation messages */
  	if (ninvalmsgs > 0)
  	{
  		rdata[lastrdata].next = &(rdata[3]);
! 		rdata[3].data = (char *) invalmsgs;
! 		rdata[3].len = ninvalmsgs * sizeof(SharedInvalidationMessage);
  		rdata[3].buffer = InvalidBuffer;
  		lastrdata = 3;
  	}
--- 1977,2034 ----
  	xlrec.xid = xid;
  	xlrec.crec.xact_time = GetCurrentTimestamp();
  	xlrec.crec.xinfo = initfileinval ? XACT_COMPLETION_UPDATE_RELCACHE_FILE : 0;
  	rdata[0].data = (char *) (&xlrec);
  	rdata[0].len = MinSizeOfXactCommitPrepared;
  	rdata[0].buffer = InvalidBuffer;
  	/* dump rels to delete */
  	if (nrels > 0)
  	{
+ 		xl_xact_commit_opt *opt_rels = (xl_xact_commit_opt *)
+ 										palloc(MinSizeOfXactCommitOpt +
+ 											nrels * sizeof(RelFileNode));
  		rdata[0].next = &(rdata[1]);
! 		xlrec.crec.xinfo |= XACT_COMPLETION_DROP_REL_NODES_PRESENT;
! 		opt_rels->nopts = nrels;
! 		memcpy(&(opt_rels->opts), rels, nrels * sizeof(RelFileNode));
! 		rdata[1].data = (char *) opt_rels;
! 		rdata[1].len = MinSizeOfXactCommitOpt +	nrels * sizeof(RelFileNode);
  		rdata[1].buffer = InvalidBuffer;
  		lastrdata = 1;
  	}
  	/* dump committed child Xids */
  	if (nchildren > 0)
  	{
+ 		xl_xact_commit_opt *opt_child =
+ 					(xl_xact_commit_opt *)
+ 									palloc(MinSizeOfXactCommitOpt +
+ 									nchildren * sizeof(TransactionId));
  		rdata[lastrdata].next = &(rdata[2]);
! 		xlrec.crec.xinfo |= XACT_COMPLETION_COMMITTED_SUB_PRESENT;
! 
! 		opt_child->nopts = nchildren;
! 		memcpy(&(opt_child->opts), children,
! 									nchildren * sizeof(TransactionId));
! 		rdata[2].data = (char *) opt_child;
! 		rdata[2].len = MinSizeOfXactCommitOpt +
! 									nchildren * sizeof(TransactionId);
  		rdata[2].buffer = InvalidBuffer;
  		lastrdata = 2;
  	}
! 	/* dump shared cache invalidation messages */
  	if (ninvalmsgs > 0)
  	{
+ 		xl_xact_commit_opt *opt_shr =
+ 							(xl_xact_commit_opt *)
+ 								palloc(MinSizeOfXactCommitOpt +
+ 								ninvalmsgs * sizeof(SharedInvalidationMessage));
  		rdata[lastrdata].next = &(rdata[3]);
! 		xlrec.crec.xinfo |= XACT_COMPLETION_SHARED_INV_PRESENT;
! 		opt_shr->nopts = ninvalmsgs;
! 		memcpy(&(opt_shr->opts), invalmsgs,
! 							ninvalmsgs * sizeof(SharedInvalidationMessage));
! 		rdata[3].data = (char *) opt_shr;
! 		rdata[3].len = MinSizeOfXactCommitOpt +
! 								ninvalmsgs * sizeof(SharedInvalidationMessage);
  		rdata[3].buffer = InvalidBuffer;
  		lastrdata = 3;
  	}
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
new file mode 100644
index 2ca1c14..730f0de
*** a/src/backend/access/transam/xact.c
--- b/src/backend/access/transam/xact.c
*************** RecordTransactionCommit(void)
*** 1003,1038 ****
  
  		SetCurrentTransactionStopTimestamp();
  		xlrec.xact_time = xactStopTimestamp;
- 		xlrec.nrels = nrels;
- 		xlrec.nsubxacts = nchildren;
- 		xlrec.nmsgs = nmsgs;
  		rdata[0].data = (char *) (&xlrec);
  		rdata[0].len = MinSizeOfXactCommit;
  		rdata[0].buffer = InvalidBuffer;
  		/* dump rels to delete */
  		if (nrels > 0)
  		{
  			rdata[0].next = &(rdata[1]);
! 			rdata[1].data = (char *) rels;
! 			rdata[1].len = nrels * sizeof(RelFileNode);
  			rdata[1].buffer = InvalidBuffer;
  			lastrdata = 1;
  		}
  		/* dump committed child Xids */
  		if (nchildren > 0)
  		{
  			rdata[lastrdata].next = &(rdata[2]);
! 			rdata[2].data = (char *) children;
! 			rdata[2].len = nchildren * sizeof(TransactionId);
  			rdata[2].buffer = InvalidBuffer;
  			lastrdata = 2;
  		}
  		/* dump shared cache invalidation messages */
  		if (nmsgs > 0)
  		{
  			rdata[lastrdata].next = &(rdata[3]);
! 			rdata[3].data = (char *) invalMessages;
! 			rdata[3].len = nmsgs * sizeof(SharedInvalidationMessage);
  			rdata[3].buffer = InvalidBuffer;
  			lastrdata = 3;
  		}
--- 1003,1060 ----
  
  		SetCurrentTransactionStopTimestamp();
  		xlrec.xact_time = xactStopTimestamp;
  		rdata[0].data = (char *) (&xlrec);
  		rdata[0].len = MinSizeOfXactCommit;
  		rdata[0].buffer = InvalidBuffer;
  		/* dump rels to delete */
  		if (nrels > 0)
  		{
+ 			xl_xact_commit_opt *opt_rels = (xl_xact_commit_opt *)
+ 											palloc(MinSizeOfXactCommitOpt +
+ 												nrels * sizeof(RelFileNode));
  			rdata[0].next = &(rdata[1]);
! 			xlrec.xinfo |= XACT_COMPLETION_DROP_REL_NODES_PRESENT;
! 			opt_rels->nopts = nrels;
! 			memcpy(&(opt_rels->opts), rels, nrels * sizeof(RelFileNode));
! 			rdata[1].data = (char *) opt_rels;
! 			rdata[1].len = MinSizeOfXactCommitOpt +	nrels * sizeof(RelFileNode);
  			rdata[1].buffer = InvalidBuffer;
  			lastrdata = 1;
  		}
  		/* dump committed child Xids */
  		if (nchildren > 0)
  		{
+ 			xl_xact_commit_opt *opt_child =
+ 						(xl_xact_commit_opt *)
+ 										palloc(MinSizeOfXactCommitOpt +
+ 										nchildren * sizeof(TransactionId));
  			rdata[lastrdata].next = &(rdata[2]);
! 			xlrec.xinfo |= XACT_COMPLETION_COMMITTED_SUB_PRESENT;
! 
! 			opt_child->nopts = nchildren;
! 			memcpy(&(opt_child->opts), children,
! 										nchildren * sizeof(TransactionId));
! 			rdata[2].data = (char *) opt_child;
! 			rdata[2].len = MinSizeOfXactCommitOpt +
! 										nchildren * sizeof(TransactionId);
  			rdata[2].buffer = InvalidBuffer;
  			lastrdata = 2;
  		}
  		/* dump shared cache invalidation messages */
  		if (nmsgs > 0)
  		{
+ 			xl_xact_commit_opt *opt_shr =
+ 								(xl_xact_commit_opt *)
+ 										palloc(MinSizeOfXactCommitOpt +
+ 										nmsgs * sizeof(SharedInvalidationMessage));
  			rdata[lastrdata].next = &(rdata[3]);
! 			xlrec.xinfo |= XACT_COMPLETION_SHARED_INV_PRESENT;
! 			opt_shr->nopts = nmsgs;
! 			memcpy(&(opt_shr->opts), invalMessages,
! 									nmsgs * sizeof(SharedInvalidationMessage));
! 			rdata[3].data = (char *) opt_shr;
! 			rdata[3].len = MinSizeOfXactCommitOpt +
! 								nmsgs * sizeof(SharedInvalidationMessage);
  			rdata[3].buffer = InvalidBuffer;
  			lastrdata = 3;
  		}
*************** xactGetCommittedChildren(TransactionId *
*** 4436,4441 ****
--- 4458,4500 ----
   *	XLOG support routines
   */
  
+ 
+ static void
+ xact_read_commit(xl_xact_commit *xlrec,
+ 					RelFileNode **drop_rels,
+ 					TransactionId **sub_xids,
+ 					SharedInvalidationMessage **inval_msgs,
+ 					int *nrels,
+ 					int *nsubxacts,
+ 					int *nmsgs)
+ {
+ 	xl_xact_commit_opt		*nextOpts = &xlrec->xnodes;
+ 	*nrels = 0;
+ 	*nsubxacts = 0;
+ 	*nmsgs = 0;
+ 
+ 	if (XactCompletionDropRelPresent(xlrec))
+ 	{
+ 		*drop_rels = (RelFileNode *) xlrec->xnodes.opts;
+ 		*nrels = xlrec->xnodes.nopts;
+ 		nextOpts = (xl_xact_commit_opt *)
+ 								&(xlrec->xnodes.opts[*nrels]);
+ 	}
+ 
+ 	if (XactCompletionCommittedSubPresent(xlrec))
+ 	{
+ 		*sub_xids = (TransactionId *) nextOpts->opts;
+ 		*nsubxacts = nextOpts->nopts;
+ 		nextOpts = (xl_xact_commit_opt *) &(nextOpts->opts[*nsubxacts]);
+ 	}
+ 
+ 	if (XactCompletionSharedInvPresent(xlrec))
+ 	{
+ 		*inval_msgs = (SharedInvalidationMessage *) nextOpts->opts;
+ 		*nmsgs = nextOpts->nopts;
+ 	}
+ }
+ 
  /*
   * Before 9.0 this was a fairly short function, but now it performs many
   * actions for which the order of execution is critical.
*************** xactGetCommittedChildren(TransactionId *
*** 4443,4459 ****
  static void
  xact_redo_commit(xl_xact_commit *xlrec, TransactionId xid, XLogRecPtr lsn)
  {
  	TransactionId *sub_xids;
  	SharedInvalidationMessage *inval_msgs;
  	TransactionId max_xid;
  	int			i;
  
! 	/* subxid array follows relfilenodes */
! 	sub_xids = (TransactionId *) &(xlrec->xnodes[xlrec->nrels]);
! 	/* invalidation messages array follows subxids */
! 	inval_msgs = (SharedInvalidationMessage *) &(sub_xids[xlrec->nsubxacts]);
! 
! 	max_xid = TransactionIdLatest(xid, xlrec->nsubxacts, sub_xids);
  
  	/*
  	 * Make sure nextXid is beyond any XID mentioned in the record.
--- 4502,4519 ----
  static void
  xact_redo_commit(xl_xact_commit *xlrec, TransactionId xid, XLogRecPtr lsn)
  {
+ 	RelFileNode		*drop_rels;
  	TransactionId *sub_xids;
  	SharedInvalidationMessage *inval_msgs;
  	TransactionId max_xid;
  	int			i;
+ 	int 		nrels = 0;
+ 	int 		nsubxacts = 0;
+ 	int 		nmsgs = 0;
  
! 	xact_read_commit(xlrec, &drop_rels, &sub_xids, &inval_msgs, &nrels,
! 						&nsubxacts, &nmsgs);
! 	max_xid = TransactionIdLatest(xid, nsubxacts, sub_xids);
  
  	/*
  	 * Make sure nextXid is beyond any XID mentioned in the record.
*************** xact_redo_commit(xl_xact_commit *xlrec, 
*** 4476,4482 ****
  		/*
  		 * Mark the transaction committed in pg_clog.
  		 */
! 		TransactionIdCommitTree(xid, xlrec->nsubxacts, sub_xids);
  	}
  	else
  	{
--- 4536,4542 ----
  		/*
  		 * Mark the transaction committed in pg_clog.
  		 */
! 		TransactionIdCommitTree(xid, nsubxacts, sub_xids);
  	}
  	else
  	{
*************** xact_redo_commit(xl_xact_commit *xlrec, 
*** 4500,4518 ****
  		 * bits set on changes made by transactions that haven't yet
  		 * recovered. It's unlikely but it's good to be safe.
  		 */
! 		TransactionIdAsyncCommitTree(xid, xlrec->nsubxacts, sub_xids, lsn);
  
  		/*
  		 * We must mark clog before we update the ProcArray.
  		 */
! 		ExpireTreeKnownAssignedTransactionIds(xid, xlrec->nsubxacts, sub_xids, max_xid);
  
  		/*
  		 * Send any cache invalidations attached to the commit. We must
  		 * maintain the same order of invalidation then release locks as
  		 * occurs in CommitTransaction().
  		 */
! 		ProcessCommittedInvalidationMessages(inval_msgs, xlrec->nmsgs,
  								  XactCompletionRelcacheInitFileInval(xlrec),
  											 xlrec->dbId, xlrec->tsId);
  
--- 4560,4578 ----
  		 * bits set on changes made by transactions that haven't yet
  		 * recovered. It's unlikely but it's good to be safe.
  		 */
! 		TransactionIdAsyncCommitTree(xid, nsubxacts, sub_xids, lsn);
  
  		/*
  		 * We must mark clog before we update the ProcArray.
  		 */
! 		ExpireTreeKnownAssignedTransactionIds(xid, nsubxacts, sub_xids, max_xid);
  
  		/*
  		 * Send any cache invalidations attached to the commit. We must
  		 * maintain the same order of invalidation then release locks as
  		 * occurs in CommitTransaction().
  		 */
! 		ProcessCommittedInvalidationMessages(inval_msgs, nmsgs,
  								  XactCompletionRelcacheInitFileInval(xlrec),
  											 xlrec->dbId, xlrec->tsId);
  
*************** xact_redo_commit(xl_xact_commit *xlrec, 
*** 4521,4540 ****
  		 * phase transactions. In effect we are ignoring the prepare phase and
  		 * just going straight to lock release.
  		 */
! 		StandbyReleaseLockTree(xid, xlrec->nsubxacts, sub_xids);
  	}
  
  	/* Make sure files supposed to be dropped are dropped */
! 	for (i = 0; i < xlrec->nrels; i++)
  	{
! 		SMgrRelation srel = smgropen(xlrec->xnodes[i], InvalidBackendId);
  		ForkNumber	fork;
  
  		for (fork = 0; fork <= MAX_FORKNUM; fork++)
  		{
  			if (smgrexists(srel, fork))
  			{
! 				XLogDropRelation(xlrec->xnodes[i], fork);
  				smgrdounlink(srel, fork, true);
  			}
  		}
--- 4581,4600 ----
  		 * phase transactions. In effect we are ignoring the prepare phase and
  		 * just going straight to lock release.
  		 */
! 		StandbyReleaseLockTree(xid, nsubxacts, sub_xids);
  	}
  
  	/* Make sure files supposed to be dropped are dropped */
! 	for (i = 0; i < nrels; i++)
  	{
! 		SMgrRelation srel = smgropen(drop_rels[i], InvalidBackendId);
  		ForkNumber	fork;
  
  		for (fork = 0; fork <= MAX_FORKNUM; fork++)
  		{
  			if (smgrexists(srel, fork))
  			{
! 				XLogDropRelation(drop_rels[i], fork);
  				smgrdounlink(srel, fork, true);
  			}
  		}
*************** xact_desc_commit(StringInfo buf, xl_xact
*** 4704,4745 ****
  {
  	int			i;
  	TransactionId *xacts;
  
! 	xacts = (TransactionId *) &xlrec->xnodes[xlrec->nrels];
  
  	appendStringInfoString(buf, timestamptz_to_str(xlrec->xact_time));
  
! 	if (xlrec->nrels > 0)
  	{
  		appendStringInfo(buf, "; rels:");
! 		for (i = 0; i < xlrec->nrels; i++)
  		{
! 			char	   *path = relpathperm(xlrec->xnodes[i], MAIN_FORKNUM);
  
  			appendStringInfo(buf, " %s", path);
  			pfree(path);
  		}
  	}
! 	if (xlrec->nsubxacts > 0)
  	{
  		appendStringInfo(buf, "; subxacts:");
! 		for (i = 0; i < xlrec->nsubxacts; i++)
  			appendStringInfo(buf, " %u", xacts[i]);
  	}
! 	if (xlrec->nmsgs > 0)
  	{
- 		SharedInvalidationMessage *msgs;
- 
- 		msgs = (SharedInvalidationMessage *) &xacts[xlrec->nsubxacts];
- 
  		if (XactCompletionRelcacheInitFileInval(xlrec))
  			appendStringInfo(buf, "; relcache init file inval dbid %u tsid %u",
  							 xlrec->dbId, xlrec->tsId);
  
  		appendStringInfo(buf, "; inval msgs:");
! 		for (i = 0; i < xlrec->nmsgs; i++)
  		{
! 			SharedInvalidationMessage *msg = &msgs[i];
  
  			if (msg->id >= 0)
  				appendStringInfo(buf, " catcache %d", msg->id);
--- 4764,4807 ----
  {
  	int			i;
  	TransactionId *xacts;
+ 	RelFileNode		*drop_rels;
+ 	SharedInvalidationMessage *inval_msgs;
+ 	int 		nrels = 0;
+ 	int 		nsubxacts = 0;
+ 	int 		nmsgs = 0;
  
! 	xact_read_commit(xlrec, &drop_rels, &xacts, &inval_msgs, &nrels,
! 						&nsubxacts, &nmsgs);
  
  	appendStringInfoString(buf, timestamptz_to_str(xlrec->xact_time));
  
! 	if (nrels > 0)
  	{
  		appendStringInfo(buf, "; rels:");
! 		for (i = 0; i < nrels; i++)
  		{
! 			char	   *path = relpathperm(drop_rels[i], MAIN_FORKNUM);
  
  			appendStringInfo(buf, " %s", path);
  			pfree(path);
  		}
  	}
! 	if (nsubxacts > 0)
  	{
  		appendStringInfo(buf, "; subxacts:");
! 		for (i = 0; i < nsubxacts; i++)
  			appendStringInfo(buf, " %u", xacts[i]);
  	}
! 	if (nmsgs > 0)
  	{
  		if (XactCompletionRelcacheInitFileInval(xlrec))
  			appendStringInfo(buf, "; relcache init file inval dbid %u tsid %u",
  							 xlrec->dbId, xlrec->tsId);
  
  		appendStringInfo(buf, "; inval msgs:");
! 		for (i = 0; i < nmsgs; i++)
  		{
! 			SharedInvalidationMessage *msg = &inval_msgs[i];
  
  			if (msg->id >= 0)
  				appendStringInfo(buf, " catcache %d", msg->id);
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
new file mode 100644
index cb440d4..9a6a7a2
*** a/src/include/access/xact.h
--- b/src/include/access/xact.h
*************** typedef struct xl_xact_assignment
*** 116,134 ****
  
  #define MinSizeOfXactAssignment offsetof(xl_xact_assignment, xsub)
  
  typedef struct xl_xact_commit
  {
  	TimestampTz xact_time;		/* time of commit */
  	uint32		xinfo;			/* info flags */
- 	int			nrels;			/* number of RelFileNodes */
- 	int			nsubxacts;		/* number of subtransaction XIDs */
- 	int			nmsgs;			/* number of shared inval msgs */
  	Oid			dbId;			/* MyDatabaseId */
  	Oid			tsId;			/* MyDatabaseTableSpace */
! 	/* Array of RelFileNode(s) to drop at commit */
! 	RelFileNode xnodes[1];		/* VARIABLE LENGTH ARRAY */
! 	/* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */
! 	/* ARRAY OF SHARED INVALIDATION MESSAGES FOLLOWS */
  } xl_xact_commit;
  
  #define MinSizeOfXactCommit offsetof(xl_xact_commit, xnodes)
--- 116,141 ----
  
  #define MinSizeOfXactAssignment offsetof(xl_xact_assignment, xsub)
  
+ typedef struct xl_xact_commit_opt
+ {
+ 	int 	nopts;
+ 	char	opts[1];
+ } xl_xact_commit_opt;
+ 
+ #define MinSizeOfXactCommitOpt offsetof(xl_xact_commit_opt, opts)
+ 
  typedef struct xl_xact_commit
  {
  	TimestampTz xact_time;		/* time of commit */
  	uint32		xinfo;			/* info flags */
  	Oid			dbId;			/* MyDatabaseId */
  	Oid			tsId;			/* MyDatabaseTableSpace */
! 	/* Array of RelFileNode(s) to drop at commit (optional) */
! 	xl_xact_commit_opt xnodes;
! 	/* ARRAY OF OPTIONAL xl_xact_commit_opt COMMITTED SUBTRANSACTION XIDs
! 	 * FOLLOWS */
! 	/* ARRAY OF OPTIONAL xl_xact_commit_opt SHARED INVALIDATION MESSAGES
! 	 * FOLLOWS */
  } xl_xact_commit;
  
  #define MinSizeOfXactCommit offsetof(xl_xact_commit, xnodes)
*************** typedef struct xl_xact_commit
*** 148,153 ****
--- 155,174 ----
  #define XactCompletionRelcacheInitFileInval(xlrec)	((xlrec)->xinfo & XACT_COMPLETION_UPDATE_RELCACHE_FILE)
  #define XactCompletionForceSyncCommit(xlrec)		((xlrec)->xinfo & XACT_COMPLETION_FORCE_SYNC_COMMIT)
  
+ /*
+  * These flags are set in the xinfo fields of WAL commit records,
+  * indicating the presence of optionals xl_xact_commit_opt structures
+  * (RelFileNodes to drop at commit, subtransaction XIDs, shared inval msgs)
+  */
+ #define XACT_COMPLETION_DROP_REL_NODES_PRESENT	0x04
+ #define XACT_COMPLETION_COMMITTED_SUB_PRESENT	0x08
+ #define XACT_COMPLETION_SHARED_INV_PRESENT		0x10
+ 
+ /* Access macros for above flags */
+ #define XactCompletionDropRelPresent(xlrec)	((xlrec)->xinfo & XACT_COMPLETION_DROP_REL_NODES_PRESENT)
+ #define XactCompletionCommittedSubPresent(xlrec)		((xlrec)->xinfo & XACT_COMPLETION_COMMITTED_SUB_PRESENT)
+ #define XactCompletionSharedInvPresent(xlrec)		((xlrec)->xinfo & XACT_COMPLETION_SHARED_INV_PRESENT)
+ 
  typedef struct xl_xact_abort
  {
  	TimestampTz xact_time;		/* time of abort */