src/include/utils/datum.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * datum.h
   4  *        POSTGRES Datum (abstract data type) manipulation routines.
   5  *
   6  * These routines are driven by the 'typbyval' and 'typlen' information,
   7  * which must previously have been obtained by the caller for the datatype
   8  * of the Datum.  (We do it this way because in most situations the caller
   9  * can look up the info just once and use it for many per-datum operations.)
  10  *
  11  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  12  * Portions Copyright (c) 1994, Regents of the University of California
  13  *
  14  * $PostgreSQL$
  15  *
  16  *-------------------------------------------------------------------------
  17  */
  18 #ifndef DATUM_H
  19 #define DATUM_H
  20
  21 /*
  22  * datumGetSize - find the "real" length of a datum
  23  */
  24 extern Size datumGetSize(Datum value, bool typByVal, int typLen);
  25
  26 /*
  27  * datumCopy - make a copy of a datum.
  28  *
  29  * If the datatype is pass-by-reference, memory is obtained with palloc().
  30  */
  31 extern Datum datumCopy(Datum value, bool typByVal, int typLen);
  32
  33 /*
  34  * datumFree - free a datum previously allocated by datumCopy, if any.
  35  *
  36  * Does nothing if datatype is pass-by-value.
  37  */
  38 extern void datumFree(Datum value, bool typByVal, int typLen);
  39
  40 /*
  41  * datumIsEqual
  42  * return true if two datums of the same type are equal, false otherwise.
  43  *
  44  * XXX : See comments in the code for restrictions!
  45  */
  46 extern bool datumIsEqual(Datum value1, Datum value2,
  47                          bool typByVal, int typLen);
  48
  49 #endif   /* DATUM_H */