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diff --git a/src/include/storage/itemptr.h b/src/include/storage/itemptr.h
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+/*-------------------------------------------------------------------------
+ *
+ * itemptr.h
+ *	  POSTGRES disk item pointer definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/itemptr.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ITEMPTR_H
+#define ITEMPTR_H
+
+#include "storage/block.h"
+#include "storage/off.h"
+
+/*
+ * ItemPointer:
+ *
+ * This is a pointer to an item within a disk page of a known file
+ * (for example, a cross-link from an index to its parent table).
+ * ip_blkid tells us which block, ip_posid tells us which entry in
+ * the linp (ItemIdData) array we want.
+ *
+ * Note: because there is an item pointer in each tuple header and index
+ * tuple header on disk, it's very important not to waste space with
+ * structure padding bytes.  The struct is designed to be six bytes long
+ * (it contains three int16 fields) but a few compilers will pad it to
+ * eight bytes unless coerced.  We apply appropriate persuasion where
+ * possible.  If your compiler can't be made to play along, you'll waste
+ * lots of space.
+ */
+typedef struct ItemPointerData
+{
+	BlockIdData ip_blkid;
+	OffsetNumber ip_posid;
+}
+
+/* If compiler understands packed and aligned pragmas, use those */
+#if defined(pg_attribute_packed) && defined(pg_attribute_aligned)
+			pg_attribute_packed()
+			pg_attribute_aligned(2)
+#endif
+ItemPointerData;
+
+typedef ItemPointerData *ItemPointer;
+
+/* ----------------
+ *		special values used in heap tuples (t_ctid)
+ * ----------------
+ */
+
+/*
+ * If a heap tuple holds a speculative insertion token rather than a real
+ * TID, ip_posid is set to SpecTokenOffsetNumber, and the token is stored in
+ * ip_blkid. SpecTokenOffsetNumber must be higher than MaxOffsetNumber, so
+ * that it can be distinguished from a valid offset number in a regular item
+ * pointer.
+ */
+#define SpecTokenOffsetNumber		0xfffe
+
+/*
+ * When a tuple is moved to a different partition by UPDATE, the t_ctid of
+ * the old tuple version is set to this magic value.
+ */
+#define MovedPartitionsOffsetNumber 0xfffd
+#define MovedPartitionsBlockNumber	InvalidBlockNumber
+
+
+/* ----------------
+ *		support macros
+ * ----------------
+ */
+
+/*
+ * ItemPointerIsValid
+ *		True iff the disk item pointer is not NULL.
+ */
+#define ItemPointerIsValid(pointer) \
+	((bool) (PointerIsValid(pointer) && ((pointer)->ip_posid != 0)))
+
+/*
+ * ItemPointerGetBlockNumberNoCheck
+ *		Returns the block number of a disk item pointer.
+ */
+#define ItemPointerGetBlockNumberNoCheck(pointer) \
+( \
+	BlockIdGetBlockNumber(&(pointer)->ip_blkid) \
+)
+
+/*
+ * ItemPointerGetBlockNumber
+ *		As above, but verifies that the item pointer looks valid.
+ */
+#define ItemPointerGetBlockNumber(pointer) \
+( \
+	AssertMacro(ItemPointerIsValid(pointer)), \
+	ItemPointerGetBlockNumberNoCheck(pointer) \
+)
+
+/*
+ * ItemPointerGetOffsetNumberNoCheck
+ *		Returns the offset number of a disk item pointer.
+ */
+#define ItemPointerGetOffsetNumberNoCheck(pointer) \
+( \
+	(pointer)->ip_posid \
+)
+
+/*
+ * ItemPointerGetOffsetNumber
+ *		As above, but verifies that the item pointer looks valid.
+ */
+#define ItemPointerGetOffsetNumber(pointer) \
+( \
+	AssertMacro(ItemPointerIsValid(pointer)), \
+	ItemPointerGetOffsetNumberNoCheck(pointer) \
+)
+
+/*
+ * ItemPointerSet
+ *		Sets a disk item pointer to the specified block and offset.
+ */
+#define ItemPointerSet(pointer, blockNumber, offNum) \
+( \
+	AssertMacro(PointerIsValid(pointer)), \
+	BlockIdSet(&((pointer)->ip_blkid), blockNumber), \
+	(pointer)->ip_posid = offNum \
+)
+
+/*
+ * ItemPointerSetBlockNumber
+ *		Sets a disk item pointer to the specified block.
+ */
+#define ItemPointerSetBlockNumber(pointer, blockNumber) \
+( \
+	AssertMacro(PointerIsValid(pointer)), \
+	BlockIdSet(&((pointer)->ip_blkid), blockNumber) \
+)
+
+/*
+ * ItemPointerSetOffsetNumber
+ *		Sets a disk item pointer to the specified offset.
+ */
+#define ItemPointerSetOffsetNumber(pointer, offsetNumber) \
+( \
+	AssertMacro(PointerIsValid(pointer)), \
+	(pointer)->ip_posid = (offsetNumber) \
+)
+
+/*
+ * ItemPointerCopy
+ *		Copies the contents of one disk item pointer to another.
+ *
+ * Should there ever be padding in an ItemPointer this would need to be handled
+ * differently as it's used as hash key.
+ */
+#define ItemPointerCopy(fromPointer, toPointer) \
+( \
+	AssertMacro(PointerIsValid(toPointer)), \
+	AssertMacro(PointerIsValid(fromPointer)), \
+	*(toPointer) = *(fromPointer) \
+)
+
+/*
+ * ItemPointerSetInvalid
+ *		Sets a disk item pointer to be invalid.
+ */
+#define ItemPointerSetInvalid(pointer) \
+( \
+	AssertMacro(PointerIsValid(pointer)), \
+	BlockIdSet(&((pointer)->ip_blkid), InvalidBlockNumber), \
+	(pointer)->ip_posid = InvalidOffsetNumber \
+)
+
+/*
+ * ItemPointerIndicatesMovedPartitions
+ *		True iff the block number indicates the tuple has moved to another
+ *		partition.
+ */
+#define ItemPointerIndicatesMovedPartitions(pointer) \
+( \
+	ItemPointerGetOffsetNumber(pointer) == MovedPartitionsOffsetNumber && \
+	ItemPointerGetBlockNumberNoCheck(pointer) == MovedPartitionsBlockNumber \
+)
+
+/*
+ * ItemPointerSetMovedPartitions
+ *		Indicate that the item referenced by the itempointer has moved into a
+ *		different partition.
+ */
+#define ItemPointerSetMovedPartitions(pointer) \
+	ItemPointerSet((pointer), MovedPartitionsBlockNumber, MovedPartitionsOffsetNumber)
+
+/* ----------------
+ *		externs
+ * ----------------
+ */
+
+extern bool ItemPointerEquals(ItemPointer pointer1, ItemPointer pointer2);
+extern int32 ItemPointerCompare(ItemPointer arg1, ItemPointer arg2);
+extern void ItemPointerInc(ItemPointer pointer);
+extern void ItemPointerDec(ItemPointer pointer);
+
+#endif							/* ITEMPTR_H */