watermark 设置的方式

 StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        DataStreamSource<Snapshot> dataStreamSource = env.addSource(new SourceFormClickhouse2());
  // 设置watermark
  WatermarkStrategy<Snapshot> snapshotWatermarkStrategy =
                WatermarkStrategy.<Snapshot>forBoundedOutOfOrderness(Duration.ofSeconds(10)).
                        withTimestampAssigner((s, timestamp) -> DateUtil.dateToStamp(s.getDateTime()));
	// 引入watermark
 SingleOutputStreamOperator<Snapshot> streamOperator = dataStreamSource.assignTimestampsAndWatermarks(snapshotWatermarkStrategy);

开窗 window (key 分组)

多个字段想分组，如何设置。
之前版本 有 keyBy(“field1,field2,field3”) 这种方法已经废弃。

1、方式一

使用元组来实现多个字段keyBy

 streamOperator.keyBy(snapshot -> Tuple2.of(snapshot.getHsSecurityId(), snapshot.getSecurityId()))
                .window(TumblingEventTimeWindows.of(Time.seconds(15)))
                .max("highPx")
                .print();

2、方式二

这种写法性能差些，也可以实现。

 streamOperator.keyBy(snapshot -> snapshot.getSecurityId())
                .keyBy(s->s.getHsSecurityId())
                .window(TumblingEventTimeWindows.of(Time.seconds(15)))
                .max("highPx")
                .print();

3、方式三

使用对象构造

 streamOperator.keyBy(snapshot -> new FieldSorting(snapshot.getSecurityId(),snapshot.getSecurityId()))
                .window(TumblingEventTimeWindows.of(Time.seconds(15)))
                .max("highPx")
                .print();