Function finalize_aggregates

src/backend/executor/nodeAgg.c:1355–1415

* Compute the final value of all aggregates for one group. * * This function handles only one grouping set at a time, which the caller must * have selected. It's also the caller's responsibility to adjust the supplied * pergroup parameter to point to the current set's transvalues. * * Results are stored in the output econtext aggvalues/aggnulls. */

 * Results are stored in the output econtext aggvalues/aggnulls.
 */
static void
finalize_aggregates(AggState *aggstate,
					AggStatePerAgg peraggs,
					AggStatePerGroup pergroup)
{
	ExprContext *econtext = aggstate->ss.ps.ps_ExprContext;
	Datum	   *aggvalues = econtext->ecxt_aggvalues;
	bool	   *aggnulls = econtext->ecxt_aggnulls;
	int			aggno;
	int			transno;

	/*
	 * If there were any DISTINCT and/or ORDER BY aggregates, sort their
	 * inputs and run the transition functions.
	 */
	for (transno = 0; transno < aggstate->numtrans; transno++)
	{
		AggStatePerTrans pertrans = &aggstate->pertrans[transno];
		AggStatePerGroup pergroupstate;
		if (!bms_is_member(transno, aggstate->aggs_used))
			continue;
		pergroupstate = &pergroup[transno];

		if (pertrans->numSortCols > 0)
		{
			Assert(aggstate->aggstrategy != AGG_HASHED &&
				   aggstate->aggstrategy != AGG_MIXED);

			if (pertrans->numInputs == 1)
				process_ordered_aggregate_single(aggstate,
												 pertrans,
												 pergroupstate);
			else
				process_ordered_aggregate_multi(aggstate,
												pertrans,
												pergroupstate);
		}
	}

	/*
	 * Run the final functions.
	 */
	for (aggno = 0; aggno < aggstate->numaggs; aggno++)
	{
		AggStatePerAgg peragg = &peraggs[aggno];
		int			transno = peragg->transno;
		AggStatePerGroup pergroupstate;

		if (!bms_is_member(transno, aggstate->aggs_used) || !peragg->aggref)
			continue;

		pergroupstate = &pergroup[transno];

		if (DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit))
			finalize_partialaggregate(aggstate, peragg, pergroupstate,
									  &aggvalues[aggno], &aggnulls[aggno]);
		else
			finalize_aggregate(aggstate, peragg, pergroupstate,