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diff --git a/src/include/utils/datum.h b/src/include/utils/datum.h
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+/*-------------------------------------------------------------------------
+ *
+ * datum.h
+ *	  POSTGRES Datum (abstract data type) manipulation routines.
+ *
+ * These routines are driven by the 'typbyval' and 'typlen' information,
+ * which must previously have been obtained by the caller for the datatype
+ * of the Datum.  (We do it this way because in most situations the caller
+ * can look up the info just once and use it for many per-datum operations.)
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/datum.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DATUM_H
+#define DATUM_H
+
+/*
+ * datumGetSize - find the "real" length of a datum
+ */
+extern Size datumGetSize(Datum value, bool typByVal, int typLen);
+
+/*
+ * datumCopy - make a copy of a non-NULL datum.
+ *
+ * If the datatype is pass-by-reference, memory is obtained with palloc().
+ */
+extern Datum datumCopy(Datum value, bool typByVal, int typLen);
+
+/*
+ * datumTransfer - transfer a non-NULL datum into the current memory context.
+ *
+ * Differs from datumCopy() in its handling of read-write expanded objects.
+ */
+extern Datum datumTransfer(Datum value, bool typByVal, int typLen);
+
+/*
+ * datumIsEqual
+ * return true if two datums of the same type are equal, false otherwise.
+ *
+ * XXX : See comments in the code for restrictions!
+ */
+extern bool datumIsEqual(Datum value1, Datum value2,
+						 bool typByVal, int typLen);
+
+/*
+ * datum_image_eq
+ *
+ * Compares two datums for identical contents, based on byte images.  Return
+ * true if the two datums are equal, false otherwise.
+ */
+extern bool datum_image_eq(Datum value1, Datum value2,
+						   bool typByVal, int typLen);
+
+/*
+ * datum_image_hash
+ *
+ * Generates hash value for 'value' based on its bits rather than logical
+ * value.
+ */
+extern uint32 datum_image_hash(Datum value, bool typByVal, int typLen);
+
+/*
+ * Serialize and restore datums so that we can transfer them to parallel
+ * workers.
+ */
+extern Size datumEstimateSpace(Datum value, bool isnull, bool typByVal,
+							   int typLen);
+extern void datumSerialize(Datum value, bool isnull, bool typByVal,
+						   int typLen, char **start_address);
+extern Datum datumRestore(char **start_address, bool *isnull);
+
+#endif							/* DATUM_H */