presto-main/src/main/java/io/prestosql/sql/planner/plan/AggregationNode.java/AggregationNode/isStreamable
class AggregationNode:    public boolean isStreamable()
    {
        return !preGroupedSymbols.isEmpty() && groupingSets.getGroupingSetCount() == 1 && groupingSets.getGlobalGroupingSets().isEmpty();
    }