Function orafce_replace_null_strings

gpcontrib/orafce/replace_empty_string.c:184–281

* Detects NULL in type text based fields and replaces them by empty string */

 * Detects NULL in type text based fields and replaces them by empty string
 */
Datum
orafce_replace_null_strings(PG_FUNCTION_ARGS)
{
	TriggerData	   *trigdata = (TriggerData *) fcinfo->context;
	HeapTuple		rettuple = NULL;
	TupleDesc		tupdesc;
	int			   *resetcols = NULL;
	Datum		   *values = NULL;
	bool		   *nulls = NULL;
	Oid				prev_typid = InvalidOid;
	bool			is_string = false;
	int				nresetcols = 0;
	int				attnum;
	bool			raise_warning = false;
	char		   *relname = NULL;

	trigger_sanity_check(fcinfo, "replace_null_strings");
	raise_warning = should_raise_warnings(fcinfo);

	rettuple = get_rettuple(fcinfo);

	/* return fast when there are not any NULL */
	if (!HeapTupleHasNulls(rettuple))
		return PointerGetDatum(rettuple);

	tupdesc = trigdata->tg_relation->rd_att;

	/* iterate over record's fields */
	for (attnum = 1; attnum <= tupdesc->natts; attnum++)
	{
		Oid typid;

		/* simple cache - lot of time columns with same type is side by side */
		typid = SPI_gettypeid(tupdesc, attnum);
		if (typid != prev_typid)
		{
			TYPCATEGORY category;
			bool		ispreferred;
			Oid base_typid;

			base_typid = getBaseType(typid);
			get_type_category_preferred(base_typid, &category, &ispreferred);

			is_string = (category == TYPCATEGORY_STRING);
			prev_typid = typid;
		}

		if (is_string)
		{
			bool		isnull;

			(void) SPI_getbinval(rettuple, tupdesc, attnum, &isnull);
			if (isnull)
			{
				if (!resetcols)
				{
					/* lazy allocation of dynamic memory */
					resetcols = palloc0(tupdesc->natts * sizeof(int));