presto-main/src/main/java/io/prestosql/operator/aggregation/builder/SpillableHashAggregationBuilder.java/SpillableHashAggregationBuilder/rebuildHashAggregationBuilder
class SpillableHashAggregationBuilder:    private void rebuildHashAggregationBuilder()
    {
        if (hashAggregationBuilder != null) {
            hashCollisions += hashAggregationBuilder.getHashCollisions();
            expectedHashCollisions += hashAggregationBuilder.getExpectedHashCollisions();
            hashAggregationBuilder.close();
        }

        hashAggregationBuilder = new InMemoryHashAggregationBuilder(
                accumulatorFactories,
                step,
                expectedGroups,
                groupByTypes,
                groupByChannels,
                hashChannel,
                operatorContext,
                Optional.of(DataSize.succinctBytes(0)),
                joinCompiler,
                () -> {
                    updateMemory();
                    // TODO: Support GroupByHash yielding in spillable hash aggregation (https://github.com/prestosql/presto/issues/460)
                    return true;
                });
        emptyHashAggregationBuilderSize = hashAggregationBuilder.getSizeInMemory();
    }