@ -7,7 +7,7 @@
* Portions Copyright ( c ) 1994 , Regents of the University of California
*
* IDENTIFICATION
* $ Header : / cvsroot / pgsql / src / backend / utils / cache / lsyscache . c , v 1.57 2001 / 08 / 21 16 : 36 : 05 tgl Exp $
* $ Header : / cvsroot / pgsql / src / backend / utils / cache / lsyscache . c , v 1.58 2001 / 09 / 06 02 : 07 : 42 tgl Exp $
*
* NOTES
* Eventually , the index information should go through here , too .
@ -750,23 +750,20 @@ get_typstorage(Oid typid)
/*
* get_typdefault
*
* Given a type OID , return the typdefault field associated with that
* type , or Datum ( NULL ) if there is no typdefault . ( This implies
* that pass - by - value types can ' t have a default value that has
* a representation of zero . Not worth fixing now . )
* The result points to palloc ' d storage for non - pass - by - value types .
* Given a type OID , return the type ' s default value , if any .
* Returns FALSE if there is no default ( effectively , default is NULL ) .
* The result points to palloc ' d storage for pass - by - reference types .
*/
Datum
get_typdefault ( Oid typid )
bool
get_typdefault ( Oid typid , Datum * defaultValue )
{
HeapTuple typeTuple ;
Form_pg_type type ;
struct varlena * typDefault ;
Oid typinput ,
typelem ;
Datum textDefaultVal ;
bool isNull ;
int32 dataSize ;
int32 typLen ;
bool typByVal ;
Datum returnValue ;
char * strDefaultVal ;
typeTuple = SearchSysCache ( TYPEOID ,
ObjectIdGetDatum ( typid ) ,
@ -777,66 +774,39 @@ get_typdefault(Oid typid)
type = ( Form_pg_type ) GETSTRUCT ( typeTuple ) ;
typinput = type - > typinput ;
typelem = type - > typelem ;
/*
* First , see if there is a non - null typdefault field ( usually there
* isn ' t )
* typdefault is potentially null , so don ' t try to access it as a struct
* field . Must do it the hard way with SysCacheGetAttr .
*/
typDefault = ( struct varlena * )
DatumGetPointer ( SysCacheGetAttr ( TYPEOID ,
textDefaultVal = SysCacheGetAttr ( TYPEOID ,
typeTuple ,
Anum_pg_type_typdefault ,
& isNull ) ) ;
& isNull ) ;
if ( isNull )
{
ReleaseSysCache ( typeTuple ) ;
return PointerGetDatum ( NULL ) ;
* defaultValue = ( Datum ) 0 ;
return false ;
}
/*
* Otherwise , extract / copy the value .
*/
dataSize = VARSIZE ( typDefault ) - VARHDRSZ ;
typLen = type - > typlen ;
typByVal = type - > typbyval ;
/* Convert text datum to C string */
strDefaultVal = DatumGetCString ( DirectFunctionCall1 ( textout ,
textDefaultVal ) ) ;
if ( typByVal )
{
if ( dataSize = = typLen )
returnValue = fetch_att ( VARDATA ( typDefault ) , typByVal , typLen ) ;
else
returnValue = PointerGetDatum ( NULL ) ;
}
else if ( typLen < 0 )
{
/* variable-size type */
if ( dataSize < 0 )
returnValue = PointerGetDatum ( NULL ) ;
else
{
returnValue = PointerGetDatum ( palloc ( VARSIZE ( typDefault ) ) ) ;
memcpy ( ( char * ) DatumGetPointer ( returnValue ) ,
( char * ) typDefault ,
( int ) VARSIZE ( typDefault ) ) ;
}
}
else
{
/* fixed-size pass-by-ref type */
if ( dataSize ! = typLen )
returnValue = PointerGetDatum ( NULL ) ;
else
{
returnValue = PointerGetDatum ( palloc ( dataSize ) ) ;
memcpy ( ( char * ) DatumGetPointer ( returnValue ) ,
VARDATA ( typDefault ) ,
( int ) dataSize ) ;
}
}
/* Convert C string to a value of the given type */
* defaultValue = OidFunctionCall3 ( typinput ,
CStringGetDatum ( strDefaultVal ) ,
ObjectIdGetDatum ( typelem ) ,
Int32GetDatum ( - 1 ) ) ;
pfree ( strDefaultVal ) ;
ReleaseSysCache ( typeTuple ) ;
return re tu rnVal ue;
return true ;
}
/*
Tom Lane
25 years ago