Function process_ordered_aggregate_multi

src/backend/executor/nodeAgg.c:979–1058

* Run the transition function for a DISTINCT or ORDER BY aggregate * with more than one input. This is called after we have completed * entering all the input values into the sort object. We complete the * sort, read out the values in sorted order, and run the transition * function on each value (applying DISTINCT if appropriate). * * This function handles only one grouping set (already se

 * When called, CurrentMemoryContext should be the per-query context.
 */
static void
process_ordered_aggregate_multi(AggState *aggstate,
								AggStatePerTrans pertrans,
								AggStatePerGroup pergroupstate)
{
	ExprContext *tmpcontext = aggstate->tmpcontext;
	FunctionCallInfo fcinfo = pertrans->transfn_fcinfo;
	TupleTableSlot *slot1 = pertrans->sortslot;
	TupleTableSlot *slot2 = pertrans->uniqslot;
	int			numTransInputs = pertrans->numTransInputs;
	int			numDistinctCols = pertrans->numDistinctCols;
	Datum		newAbbrevVal = (Datum) 0;
	Datum		oldAbbrevVal = (Datum) 0;
	bool		haveOldValue = false;
	TupleTableSlot *save = aggstate->tmpcontext->ecxt_outertuple;
	int			i;

	tuplesort_performsort(pertrans->sortstates[aggstate->current_set]);

	ExecClearTuple(slot1);
	if (slot2)
		ExecClearTuple(slot2);

	while (tuplesort_gettupleslot(pertrans->sortstates[aggstate->current_set],
								  true, true, slot1, &newAbbrevVal))
	{
		CHECK_FOR_INTERRUPTS();

		tmpcontext->ecxt_outertuple = slot1;
		tmpcontext->ecxt_innertuple = slot2;

		if (numDistinctCols == 0 ||
			!haveOldValue ||
			newAbbrevVal != oldAbbrevVal ||
			!ExecQual(pertrans->equalfnMulti, tmpcontext))
		{
			/*
			 * Extract the first numTransInputs columns as datums to pass to
			 * the transfn.
			 */
			slot_getsomeattrs(slot1, numTransInputs);

			/* Load values into fcinfo */
			/* Start from 1, since the 0th arg will be the transition value */
			for (i = 0; i < numTransInputs; i++)
			{
				fcinfo->args[i + 1].value = slot1->tts_values[i];
				fcinfo->args[i + 1].isnull = slot1->tts_isnull[i];
			}

			advance_transition_function(aggstate, pertrans, pergroupstate);

			if (numDistinctCols > 0)
			{
				/* swap the slot pointers to retain the current tuple */
				TupleTableSlot *tmpslot = slot2;

				slot2 = slot1;