本文主要是介绍Hive分析窗口函数(四) GROUPING SETS,GROUPING__ID,CUBE,ROLLUP，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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。
数据准备：
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 cookie1GROUPING 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
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,dayROLLUP
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
--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）
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。
这篇关于Hive分析窗口函数(四) GROUPING SETS,GROUPING__ID,CUBE,ROLLUP的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
