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diff --git a/src/include/access/transam.h b/src/include/access/transam.h
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+/*-------------------------------------------------------------------------
+ *
+ * transam.h
+ *	  postgres transaction access method support code
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/access/transam.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TRANSAM_H
+#define TRANSAM_H
+
+#include "access/xlogdefs.h"
+
+
+/* ----------------
+ *		Special transaction ID values
+ *
+ * BootstrapTransactionId is the XID for "bootstrap" operations, and
+ * FrozenTransactionId is used for very old tuples.  Both should
+ * always be considered valid.
+ *
+ * FirstNormalTransactionId is the first "normal" transaction id.
+ * Note: if you need to change it, you must change pg_class.h as well.
+ * ----------------
+ */
+#define InvalidTransactionId		((TransactionId) 0)
+#define BootstrapTransactionId		((TransactionId) 1)
+#define FrozenTransactionId			((TransactionId) 2)
+#define FirstNormalTransactionId	((TransactionId) 3)
+#define MaxTransactionId			((TransactionId) 0xFFFFFFFF)
+
+/* ----------------
+ *		transaction ID manipulation macros
+ * ----------------
+ */
+#define TransactionIdIsValid(xid)		((xid) != InvalidTransactionId)
+#define TransactionIdIsNormal(xid)		((xid) >= FirstNormalTransactionId)
+#define TransactionIdEquals(id1, id2)	((id1) == (id2))
+#define TransactionIdStore(xid, dest)	(*(dest) = (xid))
+#define StoreInvalidTransactionId(dest) (*(dest) = InvalidTransactionId)
+
+#define EpochFromFullTransactionId(x)	((uint32) ((x).value >> 32))
+#define XidFromFullTransactionId(x)		((uint32) (x).value)
+#define U64FromFullTransactionId(x)		((x).value)
+#define FullTransactionIdEquals(a, b)	((a).value == (b).value)
+#define FullTransactionIdPrecedes(a, b)	((a).value < (b).value)
+#define FullTransactionIdPrecedesOrEquals(a, b) ((a).value <= (b).value)
+#define FullTransactionIdFollows(a, b) ((a).value > (b).value)
+#define FullTransactionIdFollowsOrEquals(a, b) ((a).value >= (b).value)
+#define FullTransactionIdIsValid(x)		TransactionIdIsValid(XidFromFullTransactionId(x))
+#define InvalidFullTransactionId		FullTransactionIdFromEpochAndXid(0, InvalidTransactionId)
+#define FirstNormalFullTransactionId	FullTransactionIdFromEpochAndXid(0, FirstNormalTransactionId)
+#define FullTransactionIdIsNormal(x)	FullTransactionIdFollowsOrEquals(x, FirstNormalFullTransactionId)
+
+/*
+ * A 64 bit value that contains an epoch and a TransactionId.  This is
+ * wrapped in a struct to prevent implicit conversion to/from TransactionId.
+ * Not all values represent valid normal XIDs.
+ */
+typedef struct FullTransactionId
+{
+	uint64		value;
+} FullTransactionId;
+
+static inline FullTransactionId
+FullTransactionIdFromEpochAndXid(uint32 epoch, TransactionId xid)
+{
+	FullTransactionId result;
+
+	result.value = ((uint64) epoch) << 32 | xid;
+
+	return result;
+}
+
+static inline FullTransactionId
+FullTransactionIdFromU64(uint64 value)
+{
+	FullTransactionId result;
+
+	result.value = value;
+
+	return result;
+}
+
+/* advance a transaction ID variable, handling wraparound correctly */
+#define TransactionIdAdvance(dest)	\
+	do { \
+		(dest)++; \
+		if ((dest) < FirstNormalTransactionId) \
+			(dest) = FirstNormalTransactionId; \
+	} while(0)
+
+/*
+ * Retreat a FullTransactionId variable, stepping over xids that would appear
+ * to be special only when viewed as 32bit XIDs.
+ */
+static inline void
+FullTransactionIdRetreat(FullTransactionId *dest)
+{
+	dest->value--;
+
+	/*
+	 * In contrast to 32bit XIDs don't step over the "actual" special xids.
+	 * For 64bit xids these can't be reached as part of a wraparound as they
+	 * can in the 32bit case.
+	 */
+	if (FullTransactionIdPrecedes(*dest, FirstNormalFullTransactionId))
+		return;
+
+	/*
+	 * But we do need to step over XIDs that'd appear special only for 32bit
+	 * XIDs.
+	 */
+	while (XidFromFullTransactionId(*dest) < FirstNormalTransactionId)
+		dest->value--;
+}
+
+/*
+ * Advance a FullTransactionId variable, stepping over xids that would appear
+ * to be special only when viewed as 32bit XIDs.
+ */
+static inline void
+FullTransactionIdAdvance(FullTransactionId *dest)
+{
+	dest->value++;
+
+	/* see FullTransactionIdAdvance() */
+	if (FullTransactionIdPrecedes(*dest, FirstNormalFullTransactionId))
+		return;
+
+	while (XidFromFullTransactionId(*dest) < FirstNormalTransactionId)
+		dest->value++;
+}
+
+/* back up a transaction ID variable, handling wraparound correctly */
+#define TransactionIdRetreat(dest)	\
+	do { \
+		(dest)--; \
+	} while ((dest) < FirstNormalTransactionId)
+
+/* compare two XIDs already known to be normal; this is a macro for speed */
+#define NormalTransactionIdPrecedes(id1, id2) \
+	(AssertMacro(TransactionIdIsNormal(id1) && TransactionIdIsNormal(id2)), \
+	(int32) ((id1) - (id2)) < 0)
+
+/* compare two XIDs already known to be normal; this is a macro for speed */
+#define NormalTransactionIdFollows(id1, id2) \
+	(AssertMacro(TransactionIdIsNormal(id1) && TransactionIdIsNormal(id2)), \
+	(int32) ((id1) - (id2)) > 0)
+
+/* ----------
+ *		Object ID (OID) zero is InvalidOid.
+ *
+ *		OIDs 1-9999 are reserved for manual assignment (see .dat files in
+ *		src/include/catalog/).  Of these, 8000-9999 are reserved for
+ *		development purposes (such as in-progress patches and forks);
+ *		they should not appear in released versions.
+ *
+ *		OIDs 10000-11999 are reserved for assignment by genbki.pl, for use
+ *		when the .dat files in src/include/catalog/ do not specify an OID
+ *		for a catalog entry that requires one.  Note that genbki.pl assigns
+ *		these OIDs independently in each catalog, so they're not guaranteed
+ *		to be globally unique.  Furthermore, the bootstrap backend and
+ *		initdb's post-bootstrap processing can also assign OIDs in this range.
+ *		The normal OID-generation logic takes care of any OID conflicts that
+ *		might arise from that.
+ *
+ *		OIDs 12000-16383 are reserved for unpinned objects created by initdb's
+ *		post-bootstrap processing.  initdb forces the OID generator up to
+ *		12000 as soon as it's made the pinned objects it's responsible for.
+ *
+ *		OIDs beginning at 16384 are assigned from the OID generator
+ *		during normal multiuser operation.  (We force the generator up to
+ *		16384 as soon as we are in normal operation.)
+ *
+ * The choices of 8000, 10000 and 12000 are completely arbitrary, and can be
+ * moved if we run low on OIDs in any category.  Changing the macros below,
+ * and updating relevant documentation (see bki.sgml and RELEASE_CHANGES),
+ * should be sufficient to do this.  Moving the 16384 boundary between
+ * initdb-assigned OIDs and user-defined objects would be substantially
+ * more painful, however, since some user-defined OIDs will appear in
+ * on-disk data; such a change would probably break pg_upgrade.
+ *
+ * NOTE: if the OID generator wraps around, we skip over OIDs 0-16383
+ * and resume with 16384.  This minimizes the odds of OID conflict, by not
+ * reassigning OIDs that might have been assigned during initdb.  Critically,
+ * it also ensures that no user-created object will be considered pinned.
+ * ----------
+ */
+#define FirstGenbkiObjectId		10000
+#define FirstUnpinnedObjectId	12000
+#define FirstNormalObjectId		16384
+
+/*
+ * VariableCache is a data structure in shared memory that is used to track
+ * OID and XID assignment state.  For largely historical reasons, there is
+ * just one struct with different fields that are protected by different
+ * LWLocks.
+ *
+ * Note: xidWrapLimit and oldestXidDB are not "active" values, but are
+ * used just to generate useful messages when xidWarnLimit or xidStopLimit
+ * are exceeded.
+ */
+typedef struct VariableCacheData
+{
+	/*
+	 * These fields are protected by OidGenLock.
+	 */
+	Oid			nextOid;		/* next OID to assign */
+	uint32		oidCount;		/* OIDs available before must do XLOG work */
+
+	/*
+	 * These fields are protected by XidGenLock.
+	 */
+	FullTransactionId nextXid;	/* next XID to assign */
+
+	TransactionId oldestXid;	/* cluster-wide minimum datfrozenxid */
+	TransactionId xidVacLimit;	/* start forcing autovacuums here */
+	TransactionId xidWarnLimit; /* start complaining here */
+	TransactionId xidStopLimit; /* refuse to advance nextXid beyond here */
+	TransactionId xidWrapLimit; /* where the world ends */
+	Oid			oldestXidDB;	/* database with minimum datfrozenxid */
+
+	/*
+	 * These fields are protected by CommitTsLock
+	 */
+	TransactionId oldestCommitTsXid;
+	TransactionId newestCommitTsXid;
+
+	/*
+	 * These fields are protected by ProcArrayLock.
+	 */
+	FullTransactionId latestCompletedXid;	/* newest full XID that has
+											 * committed or aborted */
+
+	/*
+	 * Number of top-level transactions with xids (i.e. which may have
+	 * modified the database) that completed in some form since the start of
+	 * the server. This currently is solely used to check whether
+	 * GetSnapshotData() needs to recompute the contents of the snapshot, or
+	 * not. There are likely other users of this.  Always above 1.
+	 */
+	uint64		xactCompletionCount;
+
+	/*
+	 * These fields are protected by XactTruncationLock
+	 */
+	TransactionId oldestClogXid;	/* oldest it's safe to look up in clog */
+
+} VariableCacheData;
+
+typedef VariableCacheData *VariableCache;
+
+
+/* ----------------
+ *		extern declarations
+ * ----------------
+ */
+
+/* in transam/xact.c */
+extern bool TransactionStartedDuringRecovery(void);
+
+/* in transam/varsup.c */
+extern PGDLLIMPORT VariableCache ShmemVariableCache;
+
+/*
+ * prototypes for functions in transam/transam.c
+ */
+extern bool TransactionIdDidCommit(TransactionId transactionId);
+extern bool TransactionIdDidAbort(TransactionId transactionId);
+extern void TransactionIdCommitTree(TransactionId xid, int nxids, TransactionId *xids);
+extern void TransactionIdAsyncCommitTree(TransactionId xid, int nxids, TransactionId *xids, XLogRecPtr lsn);
+extern void TransactionIdAbortTree(TransactionId xid, int nxids, TransactionId *xids);
+extern bool TransactionIdPrecedes(TransactionId id1, TransactionId id2);
+extern bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2);
+extern bool TransactionIdFollows(TransactionId id1, TransactionId id2);
+extern bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2);
+extern TransactionId TransactionIdLatest(TransactionId mainxid,
+										 int nxids, const TransactionId *xids);
+extern XLogRecPtr TransactionIdGetCommitLSN(TransactionId xid);
+
+/* in transam/varsup.c */
+extern FullTransactionId GetNewTransactionId(bool isSubXact);
+extern void AdvanceNextFullTransactionIdPastXid(TransactionId xid);
+extern FullTransactionId ReadNextFullTransactionId(void);
+extern void SetTransactionIdLimit(TransactionId oldest_datfrozenxid,
+								  Oid oldest_datoid);
+extern void AdvanceOldestClogXid(TransactionId oldest_datfrozenxid);
+extern bool ForceTransactionIdLimitUpdate(void);
+extern Oid	GetNewObjectId(void);
+extern void StopGeneratingPinnedObjectIds(void);
+
+#ifdef USE_ASSERT_CHECKING
+extern void AssertTransactionIdInAllowableRange(TransactionId xid);
+#else
+#define AssertTransactionIdInAllowableRange(xid) ((void)true)
+#endif
+
+/*
+ * Some frontend programs include this header.  For compilers that emit static
+ * inline functions even when they're unused, that leads to unsatisfied
+ * external references; hence hide them with #ifndef FRONTEND.
+ */
+#ifndef FRONTEND
+
+/*
+ * For callers that just need the XID part of the next transaction ID.
+ */
+static inline TransactionId
+ReadNextTransactionId(void)
+{
+	return XidFromFullTransactionId(ReadNextFullTransactionId());
+}
+
+/* return transaction ID backed up by amount, handling wraparound correctly */
+static inline TransactionId
+TransactionIdRetreatedBy(TransactionId xid, uint32 amount)
+{
+	xid -= amount;
+
+	while (xid < FirstNormalTransactionId)
+		xid--;
+
+	return xid;
+}
+
+/* return the older of the two IDs */
+static inline TransactionId
+TransactionIdOlder(TransactionId a, TransactionId b)
+{
+	if (!TransactionIdIsValid(a))
+		return b;
+
+	if (!TransactionIdIsValid(b))
+		return a;
+
+	if (TransactionIdPrecedes(a, b))
+		return a;
+	return b;
+}
+
+/* return the older of the two IDs, assuming they're both normal */
+static inline TransactionId
+NormalTransactionIdOlder(TransactionId a, TransactionId b)
+{
+	Assert(TransactionIdIsNormal(a));
+	Assert(TransactionIdIsNormal(b));
+	if (NormalTransactionIdPrecedes(a, b))
+		return a;
+	return b;
+}
+
+/* return the newer of the two IDs */
+static inline FullTransactionId
+FullTransactionIdNewer(FullTransactionId a, FullTransactionId b)
+{
+	if (!FullTransactionIdIsValid(a))
+		return b;
+
+	if (!FullTransactionIdIsValid(b))
+		return a;
+
+	if (FullTransactionIdFollows(a, b))
+		return a;
+	return b;
+}
+
+#endif							/* FRONTEND */
+
+#endif							/* TRANSAM_H */