Impala SQL:将行与重叠日期合并.存在的地方和不支持递归的CTE

Question

我试图将行与Impala SQL中表中的重叠日期间隔合并。但是，我发现解决此问题的解决方案不受Impala的支持。存在和递归ctes。

我将如何在Impala中为此编写查询？

    Table: @T
    ID  StartDate   EndDate
    1   20170101    20170201
    2   20170101    20170401
    3   20170505    20170531    
    4   20170530    20170531
    5   20170530    20170831
    6   20171001    20171005
    7   20171101    20171225
    8   20171105    20171110
    Required Output:
    StartDate   EndDate
    20170101    20170401
    20170505    20170831
    20171001    20171005

Impala中不支持我要实现的目标：

    SELECT 
           s1.StartDate,
           MIN(t1.EndDate) AS EndDate
    FROM @T s1 
    INNER JOIN @T t1 ON s1.StartDate <= t1.EndDate
      AND NOT EXISTS(SELECT * FROM @T t2 
             WHERE t1.EndDate >= t2.StartDate AND t1.EndDate < t2.EndDate) 
    WHERE NOT EXISTS(SELECT * FROM @T s2 
                     WHERE s1.StartDate > s2.StartDate AND s1.StartDate <= s2.EndDate) 
    GROUP BY s1.StartDate 
    ORDER BY s1.StartDate 

类似的问题：

合并重叠日期间隔

消除并减少重叠日期范围

https://gerireshef.wordpress.com/2010/05/02/packing-date-intervals/

https://www.sqlservercentral.com/forums/topic826031-8-1.aspx

Answer 1

select  min(StartDate)  as StartDate
       ,max(EndDate)    as EndDate
from   (select  StartDate,EndDate
               ,count (is_gap) over
                (
                    order by    StartDate,ID
                )   as range_id
        from   (select  ID,StartDate,EndDate
                       ,case 
                            when    max (EndDate) over
                                    (
                                        order by    StartDate,ID
                                        rows        between unbounded preceding 
                                                    and     1 preceding
                                    ) < StartDate
                            then    true
                        end as is_gap
                from    t
                ) t
        ) t
group by    range_id
order by    StartDate
;

---

+------------+------------+
| startdate  | enddate    |
+------------+------------+
| 2017-01-01 | 2017-04-01 |
| 2017-05-05 | 2017-08-31 |
| 2017-10-01 | 2017-10-05 |
| 2017-11-01 | 2017-12-25 |
+------------+------------+