Function hashagg_spill_finish

src/backend/executor/nodeAgg.c:3416–3453

* hashagg_spill_finish * * Transform spill partitions into new batches. */

 * Transform spill partitions into new batches.
 */
static void
hashagg_spill_finish(AggState *aggstate, HashAggSpill *spill, int setno)
{
	int			i;
	int			used_bits = 32 - spill->shift;

	if (spill->npartitions == 0)
		return;					/* didn't spill */

	for (i = 0; i < spill->npartitions; i++)
	{
		LogicalTapeSet *tapeset = aggstate->hash_tapeinfo->tapeset;
		int			tapenum = spill->partitions[i];
		HashAggBatch *new_batch;
		double		cardinality;

		/* if the partition is empty, don't create a new batch of work */
		if (spill->ntuples[i] == 0)
			continue;

		cardinality = estimateHyperLogLog(&spill->hll_card[i]);
		freeHyperLogLog(&spill->hll_card[i]);

		/* rewinding frees the buffer while not in use */
		LogicalTapeRewindForRead(tapeset, tapenum,
								 HASHAGG_READ_BUFFER_SIZE);

		new_batch = hashagg_batch_new(tapeset, tapenum, setno,
									  spill->ntuples[i], cardinality,
									  used_bits);
		aggstate->hash_batches = lappend(aggstate->hash_batches, new_batch);
		aggstate->hash_batches_used++;
	}

	pfree(spill->ntuples);
	pfree(spill->hll_card);
	pfree(spill->partitions);
}

/*
 * Free resources related to a spilled HashAgg.