Function array_agg_deserialize

src/backend/utils/adt/array_userfuncs.c:745–867

}

Datum
array_agg_deserialize(PG_FUNCTION_ARGS)
{
	bytea	   *sstate;
	ArrayBuildState *result;
	StringInfoData buf;
	Oid			element_type;
	int64		nelems;
	const char *temp;

	if (!AggCheckCallContext(fcinfo, NULL))
		elog(ERROR, "aggregate function called in non-aggregate context");

	sstate = PG_GETARG_BYTEA_PP(0);

	/*
	 * Copy the bytea into a StringInfo so that we can "receive" it using the
	 * standard recv-function infrastructure.
	 */
	initStringInfo(&buf);
	appendBinaryStringInfo(&buf,
						   VARDATA_ANY(sstate), VARSIZE_ANY_EXHDR(sstate));

	/* element_type */
	element_type = pq_getmsgint(&buf, sizeof(Oid));

	/* nelems */
	nelems = pq_getmsgint64(&buf);

	/* Create output ArrayBuildState with the needed number of elements */
	result = initArrayResultWithSize(element_type, CurrentMemoryContext,
									 false, nelems);
	result->nelems = nelems;

	/* typlen */
	result->typlen = pq_getmsgint(&buf, sizeof(int16));

	/* typbyval */
	result->typbyval = pq_getmsgbyte(&buf);

	/* typalign */
	result->typalign = pq_getmsgbyte(&buf);

	/* dnulls */
	temp = pq_getmsgbytes(&buf, sizeof(bool) * nelems);
	memcpy(result->dnulls, temp, sizeof(bool) * nelems);

	/* dvalues --- see comment in array_agg_serialize */
	if (result->typbyval)
	{
		temp = pq_getmsgbytes(&buf, sizeof(Datum) * nelems);
		memcpy(result->dvalues, temp, sizeof(Datum) * nelems);
	}
	else
	{
		DeserialIOData *iodata;
		int			i;