public static SelectResults createResultCollection(boolean distinct, ObjectType elementType,
      ExecutionContext context) {
    return distinct ? new ResultsSet(elementType)
        : new ResultsBag(elementType, context.getCachePerfStats());
  }
Return a SelectResults that is the union of c1 and c2. May or may not return a modified c1 or
c2.
geode-core/src/main/java/org/apache/geode/cache/query/internal/QueryUtils.java