groupBy 分组 分组字段值一样的在一组里
sortGroup  组内排序




final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
String file = "file:/path/events.txt";
DataSet<Tuple5<String,String,String,String, Double>> csvInput = env.readCsvFile(file)
        .types(String.class,String.class,String.class,String.class, Double.class);
            
csvInput.groupBy(2)
        .sortGroup(3, Order.ASCENDING)
        .sortGroup(1, Order.DESCENDING)       
        .combineGroup(new MyGroupCombineFunction())
        .print();
        

private static class MyGroupCombineFunction implements GroupCombineFunction<Tuple5<String,String,String,String, Double>,String>{
    private static final long serialVersionUID = 1L;

    public void combine(Iterable<Tuple5<String,String,String,String, Double>> values, Collector<String> out) throws Exception{
        for(Tuple5<String,String,String,String, Double> item:values) {
            out.collect(item.toString());       
        }   
            out.collect("-------");
    }
} 
 
以下两者的区别
  
csvInput.groupBy(2)
        .sortGroup(3, Order.ASCENDING)
        .sortGroup(1, Order.DESCENDING)
  
  
csvInput.groupBy(2,3)
.sortGroup(1, Order.DESCENDING)
  


groupBy 相同的key在一起

第一种输出
第3个字段一样的在一组里

(6,2021-01-03 03:00:00,a,b,6.0)
(5,2021-01-03 02:00:00,a,b,5.0)
(1,2021-01-01 00:00:00,a,b,1.0)
(11,2021-01-05 01:00:00,a,c,5.0)
(10,2021-01-05 00:00:00,a,c,3.0)
(2,2021-01-02 00:00:00,a,c,2.0)
(4,2021-01-03 01:00:00,a,d,4.0)
-------
(9,2021-01-04 00:00:00,b,a,3.0)
(8,2021-01-03 05:00:00,b,a,2.0)
(3,2021-01-03 00:00:00,b,a,3.0)
(7,2021-01-03 04:00:00,b,c,1.0)
-------
(0,2021-01-05 01:00:00,c,a,5.0)
-------





第二种输出
第3第4两字段一样的在一组里

(6,2021-01-03 03:00:00,a,b,6.0)
(5,2021-01-03 02:00:00,a,b,5.0)
(1,2021-01-01 00:00:00,a,b,1.0)
-------
(11,2021-01-05 01:00:00,a,c,5.0)
(10,2021-01-05 00:00:00,a,c,3.0)
(2,2021-01-02 00:00:00,a,c,2.0)
-------
(4,2021-01-03 01:00:00,a,d,4.0)
-------
(9,2021-01-04 00:00:00,b,a,3.0)
(8,2021-01-03 05:00:00,b,a,2.0)
(3,2021-01-03 00:00:00,b,a,3.0)
-------
(7,2021-01-03 04:00:00,b,c,1.0)
-------
(0,2021-01-05 01:00:00,c,a,5.0)
-------


完整代码

https://gitee.com/dyyx/demos/blob/master/flinkdemo/src/main/java/dyyx/zb/EventsGroupAndSort3.java

https://gitee.com/dyyx/demos/blob/master/flinkdemo/src/main/java/dyyx/zb/EventsGroupAndSort4.java

测试数据
https://gitee.com/dyyx/demos/blob/master/flinkdemo/docs/data/events.txt