77 lines
2.3 KiB
C
77 lines
2.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* datum.h
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* POSTGRES Datum (abstract data type) manipulation routines.
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*
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* These routines are driven by the 'typbyval' and 'typlen' information,
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* which must previously have been obtained by the caller for the datatype
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* of the Datum. (We do it this way because in most situations the caller
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* can look up the info just once and use it for many per-datum operations.)
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*
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* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/datum.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef DATUM_H
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#define DATUM_H
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/*
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* datumGetSize - find the "real" length of a datum
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*/
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extern Size datumGetSize(Datum value, bool typByVal, int typLen);
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/*
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* datumCopy - make a copy of a non-NULL datum.
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*
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* If the datatype is pass-by-reference, memory is obtained with palloc().
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*/
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extern Datum datumCopy(Datum value, bool typByVal, int typLen);
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/*
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* datumTransfer - transfer a non-NULL datum into the current memory context.
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*
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* Differs from datumCopy() in its handling of read-write expanded objects.
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*/
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extern Datum datumTransfer(Datum value, bool typByVal, int typLen);
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/*
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* datumIsEqual
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* return true if two datums of the same type are equal, false otherwise.
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*
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* XXX : See comments in the code for restrictions!
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*/
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extern bool datumIsEqual(Datum value1, Datum value2,
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bool typByVal, int typLen);
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/*
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* datum_image_eq
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*
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* Compares two datums for identical contents, based on byte images. Return
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* true if the two datums are equal, false otherwise.
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*/
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extern bool datum_image_eq(Datum value1, Datum value2,
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bool typByVal, int typLen);
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/*
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* datum_image_hash
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*
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* Generates hash value for 'value' based on its bits rather than logical
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* value.
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*/
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extern uint32 datum_image_hash(Datum value, bool typByVal, int typLen);
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/*
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* Serialize and restore datums so that we can transfer them to parallel
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* workers.
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*/
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extern Size datumEstimateSpace(Datum value, bool isnull, bool typByVal,
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int typLen);
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extern void datumSerialize(Datum value, bool isnull, bool typByVal,
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int typLen, char **start_address);
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extern Datum datumRestore(char **start_address, bool *isnull);
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#endif /* DATUM_H */
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