问题导读
1.GROUPING SETS与另外哪种方式等价?
2.根据GROUP BY的维度的所有组合进行聚合由哪个关键字完成?
3.ROLLUP与ROLLUP关系是什么?
接上篇
Hive分析窗口函数(四) LAG,LEAD,FIRST_VALUE,LAST_VALUE
GROUPING SETS,GROUPING__ID,CUBE,ROLLUP 这几个分析函数通常用于OLAP中,不能累加,而且需要根据不同维度上钻和下钻的指标统计,比如,分小时、天、月的UV数。 Hive版本为 apache-hive-0.13.1数据准备:
- 2015-03,2015-03-10,cookie1
- 2015-03,2015-03-10,cookie5
- 2015-03,2015-03-12,cookie7
- 2015-04,2015-04-12,cookie3
- 2015-04,2015-04-13,cookie2
- 2015-04,2015-04-13,cookie4
- 2015-04,2015-04-16,cookie4
- 2015-03,2015-03-10,cookie2
- 2015-03,2015-03-10,cookie3
- 2015-04,2015-04-12,cookie5
- 2015-04,2015-04-13,cookie6
- 2015-04,2015-04-15,cookie3
- 2015-04,2015-04-15,cookie2
- 2015-04,2015-04-16,cookie1
-
- CREATE EXTERNAL TABLE lxw1234 (
- month STRING,
- day STRING,
- cookieid STRING
- ) ROW FORMAT DELIMITED
- FIELDS TERMINATED BY ','
- stored as textfile location '/tmp/lxw11/';
-
-
- hive> select * from lxw1234;
- OK
- 2015-03 2015-03-10 cookie1
- 2015-03 2015-03-10 cookie5
- 2015-03 2015-03-12 cookie7
- 2015-04 2015-04-12 cookie3
- 2015-04 2015-04-13 cookie2
- 2015-04 2015-04-13 cookie4
- 2015-04 2015-04-16 cookie4
- 2015-03 2015-03-10 cookie2
- 2015-03 2015-03-10 cookie3
- 2015-04 2015-04-12 cookie5
- 2015-04 2015-04-13 cookie6
- 2015-04 2015-04-15 cookie3
- 2015-04 2015-04-15 cookie2
- 2015-04 2015-04-16 cookie1
复制代码
GROUPING SETS
在一个GROUP BY查询中,根据不同的维度组合进行聚合,等价于将不同维度的GROUP BY结果集进行UNION ALL - SELECT
- month,
- day,
- COUNT(DISTINCT cookieid) AS uv,
- GROUPING__ID
- FROM lxw1234
- GROUP BY month,day
- GROUPING SETS (month,day)
- ORDER BY GROUPING__ID;
-
- month day uv GROUPING__ID
- ------------------------------------------------
- 2015-03 NULL 5 1
- 2015-04 NULL 6 1
- NULL 2015-03-10 4 2
- NULL 2015-03-12 1 2
- NULL 2015-04-12 2 2
- NULL 2015-04-13 3 2
- NULL 2015-04-15 2 2
- NULL 2015-04-16 2 2
-
-
- 等价于
- SELECT month,NULL,COUNT(DISTINCT cookieid) AS uv,1 AS GROUPING__ID FROM lxw1234 GROUP BY month
- UNION ALL
- SELECT NULL,day,COUNT(DISTINCT cookieid) AS uv,2 AS GROUPING__ID FROM lxw1234 GROUP BY day
复制代码
再如: - SELECT
- month,
- day,
- COUNT(DISTINCT cookieid) AS uv,
- GROUPING__ID
- FROM lxw1234
- GROUP BY month,day
- GROUPING SETS (month,day,(month,day))
- ORDER BY GROUPING__ID;
-
- month day uv GROUPING__ID
- ------------------------------------------------
- 2015-03 NULL 5 1
- 2015-04 NULL 6 1
- NULL 2015-03-10 4 2
- NULL 2015-03-12 1 2
- NULL 2015-04-12 2 2
- NULL 2015-04-13 3 2
- NULL 2015-04-15 2 2
- NULL 2015-04-16 2 2
- 2015-03 2015-03-10 4 3
- 2015-03 2015-03-12 1 3
- 2015-04 2015-04-12 2 3
- 2015-04 2015-04-13 3 3
- 2015-04 2015-04-15 2 3
- 2015-04 2015-04-16 2 3
-
-
- 等价于
- SELECT month,NULL,COUNT(DISTINCT cookieid) AS uv,1 AS GROUPING__ID FROM lxw1234 GROUP BY month
- UNION ALL
- SELECT NULL,day,COUNT(DISTINCT cookieid) AS uv,2 AS GROUPING__ID FROM lxw1234 GROUP BY day
- UNION ALL
- SELECT month,day,COUNT(DISTINCT cookieid) AS uv,3 AS GROUPING__ID FROM lxw1234 GROUP BY month,day
复制代码
其中的 GROUPING__ID,表示结果属于哪一个分组集合。
CUBE
根据GROUP BY的维度的所有组合进行聚合。 - SELECT
- month,
- day,
- COUNT(DISTINCT cookieid) AS uv,
- GROUPING__ID
- FROM lxw1234
- GROUP BY month,day
- WITH CUBE
- ORDER BY GROUPING__ID;
-
-
- month day uv GROUPING__ID
- --------------------------------------------
- NULL NULL 7 0
- 2015-03 NULL 5 1
- 2015-04 NULL 6 1
- NULL 2015-04-12 2 2
- NULL 2015-04-13 3 2
- NULL 2015-04-15 2 2
- NULL 2015-04-16 2 2
- NULL 2015-03-10 4 2
- NULL 2015-03-12 1 2
- 2015-03 2015-03-10 4 3
- 2015-03 2015-03-12 1 3
- 2015-04 2015-04-16 2 3
- 2015-04 2015-04-12 2 3
- 2015-04 2015-04-13 3 3
- 2015-04 2015-04-15 2 3
-
-
-
- 等价于
- SELECT NULL,NULL,COUNT(DISTINCT cookieid) AS uv,0 AS GROUPING__ID FROM lxw1234
- UNION ALL
- SELECT month,NULL,COUNT(DISTINCT cookieid) AS uv,1 AS GROUPING__ID FROM lxw1234 GROUP BY month
- UNION ALL
- SELECT NULL,day,COUNT(DISTINCT cookieid) AS uv,2 AS GROUPING__ID FROM lxw1234 GROUP BY day
- UNION ALL
- SELECT month,day,COUNT(DISTINCT cookieid) AS uv,3 AS GROUPING__ID FROM lxw1234 GROUP BY month,day
复制代码
ROLLUP
是CUBE的子集,以最左侧的维度为主,从该维度进行层级聚合。 - 比如,以month维度进行层级聚合:
- SELECT
- month,
- day,
- COUNT(DISTINCT cookieid) AS uv,
- GROUPING__ID
- FROM lxw1234
- GROUP BY month,day
- WITH ROLLUP
- ORDER BY GROUPING__ID;
-
- month day uv GROUPING__ID
- ---------------------------------------------------
- NULL NULL 7 0
- 2015-03 NULL 5 1
- 2015-04 NULL 6 1
- 2015-03 2015-03-10 4 3
- 2015-03 2015-03-12 1 3
- 2015-04 2015-04-12 2 3
- 2015-04 2015-04-13 3 3
- 2015-04 2015-04-15 2 3
- 2015-04 2015-04-16 2 3
-
- 可以实现这样的上钻过程:
- 月天的UV->月的UV->总UV
复制代码
- --把month和day调换顺序,则以day维度进行层级聚合:
-
- SELECT
- day,
- month,
- COUNT(DISTINCT cookieid) AS uv,
- GROUPING__ID
- FROM lxw1234
- GROUP BY day,month
- WITH ROLLUP
- ORDER BY GROUPING__ID;
-
-
- day month uv GROUPING__ID
- -------------------------------------------------------
- NULL NULL 7 0
- 2015-04-13 NULL 3 1
- 2015-03-12 NULL 1 1
- 2015-04-15 NULL 2 1
- 2015-03-10 NULL 4 1
- 2015-04-16 NULL 2 1
- 2015-04-12 NULL 2 1
- 2015-04-12 2015-04 2 3
- 2015-03-10 2015-03 4 3
- 2015-03-12 2015-03 1 3
- 2015-04-13 2015-04 3 3
- 2015-04-15 2015-04 2 3
- 2015-04-16 2015-04 2 3
-
- 可以实现这样的上钻过程:
- 天月的UV->天的UV->总UV
- (这里,根据天和月进行聚合,和根据天聚合结果一样,因为有父子关系,如果是其他维度组合的话,就会不一样)
复制代码
这种函数,需要结合实际场景和数据去使用和研究,只看说明的话,很难理解。
相关内容:
Hive分析窗口函数(一) SUM,AVG,MIN,MAX
Hive分析窗口函数(二) NTILE,ROW_NUMBER,RANK,DENSE_RANK
Hive分析窗口函数(四) LAG,LEAD,FIRST_VALUE,LAST_VALUE
Hive分析窗口函数(五) GROUPING SETS,GROUPING__ID,CUBE,ROLLUP
来源:西安 大数据 » Hive分析窗口函数(五) GROUPING SETS,GROUPING__ID,CUBE,ROLLUP
|