@Override public void addToDag(Planner p) { if (wDef.kind() == SESSION) { addSessionWindow(p, wDef.downcast()); } else if (aggrOp.combineFn() == null) { // We don't use single-stage even when optimizing for memory because the // single-stage setup doesn't save memory with just one global key. addSlidingWindowSingleStage(p, wDef.downcast()); } else { addSlidingWindowTwoStage(p, wDef.downcast()); } }