Function ExecParallelHashTableAlloc

src/backend/executor/nodeHash.c:3813–3827

* Allocate an empty shared memory hash table for a given batch. */

 * Allocate an empty shared memory hash table for a given batch.
 */
void
ExecParallelHashTableAlloc(HashJoinTable hashtable, int batchno)
{
	ParallelHashJoinBatch *batch = hashtable->batches[batchno].shared;
	dsa_pointer_atomic *buckets;
	int			nbuckets = hashtable->parallel_state->nbuckets;
	int			i;

	batch->buckets =
		dsa_allocate(hashtable->area, sizeof(dsa_pointer_atomic) * nbuckets);
	buckets = (dsa_pointer_atomic *)
		dsa_get_address(hashtable->area, batch->buckets);
	for (i = 0; i < nbuckets; ++i)
		dsa_pointer_atomic_init(&buckets[i], InvalidDsaPointer);
}

/*
 * If we are currently attached to a shared hash join batch, detach.  If we