Function numeric_deserialize

src/backend/utils/adt/numeric.c:5234–5297

* numeric_deserialize * Deserialization function for NumericAggState for numeric aggregates that * require sumX2. Deserializes bytea into into NumericAggState using the * standard pq API. * * numeric_serialize(numeric_deserialize(bytea)) must result in a value which * matches the original bytea value. */

 * matches the original bytea value.
 */
Datum
numeric_deserialize(PG_FUNCTION_ARGS)
{
	bytea	   *sstate;
	NumericAggState *result;
	Datum		temp;
	NumericVar	sumX_var;
	NumericVar	sumX2_var;
	StringInfoData buf;

	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));

	result = makeNumericAggStateCurrentContext(false);

	/* N */
	result->N = pq_getmsgint64(&buf);

	/* sumX */
	temp = DirectFunctionCall3(numeric_recv,
							   PointerGetDatum(&buf),
							   ObjectIdGetDatum(InvalidOid),
							   Int32GetDatum(-1));
	init_var_from_num(DatumGetNumeric(temp), &sumX_var);
	accum_sum_add(&(result->sumX), &sumX_var);

	/* sumX2 */
	temp = DirectFunctionCall3(numeric_recv,
							   PointerGetDatum(&buf),
							   ObjectIdGetDatum(InvalidOid),
							   Int32GetDatum(-1));
	init_var_from_num(DatumGetNumeric(temp), &sumX2_var);
	accum_sum_add(&(result->sumX2), &sumX2_var);

	/* maxScale */
	result->maxScale = pq_getmsgint(&buf, 4);

	/* maxScaleCount */
	result->maxScaleCount = pq_getmsgint64(&buf);

	/* NaNcount */
	result->NaNcount = pq_getmsgint64(&buf);

	/* pInfcount */
	result->pInfcount = pq_getmsgint64(&buf);

	/* nInfcount */
	result->nInfcount = pq_getmsgint64(&buf);