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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 */
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