Function hash_agg_enter_spill_mode

src/backend/executor/nodeAgg.c:1952–1992

* Enter "spill mode", meaning that no new groups are added to any of the hash * tables. Tuples that would create a new group are instead spilled, and * processed later. */

 * processed later.
 */
static void
hash_agg_enter_spill_mode(AggState *aggstate)
{
	if (aggstate->streaming)
	{
		/* don't spill, only mark the hash table as filled. */
		aggstate->table_filled = true;
		return;
	}

	aggstate->hash_spill_mode = true;
	hashagg_recompile_expressions(aggstate, aggstate->table_filled, true);

	if (!aggstate->hash_ever_spilled)
	{
		Assert(aggstate->hash_tapeinfo == NULL);
		Assert(aggstate->hash_spills == NULL);

		aggstate->hash_ever_spilled = true;

		hashagg_tapeinfo_init(aggstate);

		aggstate->hash_spills = palloc(sizeof(HashAggSpill) * aggstate->num_hashes);

		for (int setno = 0; setno < aggstate->num_hashes; setno++)
		{
			AggStatePerHash perhash = &aggstate->perhash[setno];
			HashAggSpill *spill = &aggstate->hash_spills[setno];

			hashagg_spill_init(aggstate, spill, aggstate->hash_tapeinfo, 0,
							   perhash->aggnode->numGroups,
							   aggstate->hashentrysize);
			perhash->num_spill_parts += spill->npartitions;
		}

		if (aggstate->ss.ps.instrument)
		{
			aggstate->ss.ps.instrument->workfileCreated = true;
		}
	}
}

/*
 * Update metrics after filling the hash table.