Function array_send

src/backend/utils/adt/arrayfuncs.c:1561–1659

* array_send : * takes the internal representation of an array and returns a bytea * containing the array in its external binary format. */

 *		  containing the array in its external binary format.
 */
Datum
array_send(PG_FUNCTION_ARGS)
{
	AnyArrayType *v = PG_GETARG_ANY_ARRAY_P(0);
	Oid			element_type = AARR_ELEMTYPE(v);
	int			typlen;
	bool		typbyval;
	char		typalign;
	int			nitems,
				i;
	int			ndim,
			   *dim,
			   *lb;
	StringInfoData buf;
	array_iter	iter;
	ArrayMetaState *my_extra;

	/*
	 * We arrange to look up info about element type, including its send
	 * conversion proc, only once per series of calls, assuming the element
	 * type doesn't change underneath us.
	 */
	my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
	if (my_extra == NULL)
	{
		fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
													  sizeof(ArrayMetaState));
		my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
		my_extra->element_type = ~element_type;
	}

	if (my_extra->element_type != element_type)
	{
		/* Get info about element type, including its send proc */
		get_type_io_data(element_type, IOFunc_send,
						 &my_extra->typlen, &my_extra->typbyval,
						 &my_extra->typalign, &my_extra->typdelim,
						 &my_extra->typioparam, &my_extra->typiofunc);
		if (!OidIsValid(my_extra->typiofunc))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_FUNCTION),
					 errmsg("no binary output function available for type %s",
							format_type_be(element_type))));
		fmgr_info_cxt(my_extra->typiofunc, &my_extra->proc,
					  fcinfo->flinfo->fn_mcxt);
		my_extra->element_type = element_type;
	}
	typlen = my_extra->typlen;
	typbyval = my_extra->typbyval;
	typalign = my_extra->typalign;

	ndim = AARR_NDIM(v);
	dim = AARR_DIMS(v);
	lb = AARR_LBOUND(v);
	nitems = ArrayGetNItems(ndim, dim);

	pq_begintypsend(&buf);