Function EstimateParamExecSpace

src/backend/executor/execParallel.c:313–347

* Estimate the amount of space required to serialize the indicated parameters. */

 * Estimate the amount of space required to serialize the indicated parameters.
 */
static Size
EstimateParamExecSpace(EState *estate, Bitmapset *params)
{
	int			paramid;
	Size		sz = sizeof(int);

	paramid = -1;
	while ((paramid = bms_next_member(params, paramid)) >= 0)
	{
		Oid			typeOid;
		int16		typLen;
		bool		typByVal;
		ParamExecData *prm;

		prm = &(estate->es_param_exec_vals[paramid]);
		typeOid = list_nth_oid(estate->es_plannedstmt->paramExecTypes,
							   paramid);

		sz = add_size(sz, sizeof(int)); /* space for paramid */

		/* space for datum/isnull */
		if (OidIsValid(typeOid))
			get_typlenbyval(typeOid, &typLen, &typByVal);
		else
		{
			/* If no type OID, assume by-value, like copyParamList does. */
			typLen = sizeof(Datum);
			typByVal = true;
		}
		sz = add_size(sz,
					  datumEstimateSpace(prm->value, prm->isnull,
										 typByVal, typLen));
	}
	return sz;
}

/*
 * Serialize specified PARAM_EXEC parameters.