2017-07-20#Hive Analytics Functions : row_number rank over

2017-07-20#Hive Analytics Functions : row_number rank over

在做数据分析是，会统计用户访问app不同页面的开始时间，理论上同一个用户访问不同页面的开始时间应该不同。为了排查app端是否存在bug，用到row_number() over () 窗口函数。

row_number over

sql如下

select
a.gu_id,starttime,
row_number() over (partition by gu_id order by starttime) rn
from test.fct_path_list_off_5levels a
where a.date = '2017-07-19'
and gu_id = "00000000-0000-0030-ffff-ffffef748aff";

效果如下：

a.gu_id	starttime	rn
00000000-0000-0030-ffff-ffffef748aff	1500437284798	1
00000000-0000-0030-ffff-ffffef748aff	1500437284798	2
00000000-0000-0030-ffff-ffffef748aff	1500437285979	3
00000000-0000-0030-ffff-ffffef748aff	1500437286845	4
00000000-0000-0030-ffff-ffffef748aff	1500437287872	5
00000000-0000-0030-ffff-ffffef748aff	1500437290902	6
00000000-0000-0030-ffff-ffffef748aff	1500437291624	7
00000000-0000-0030-ffff-ffffef748aff	1500437298189	8
00000000-0000-0030-ffff-ffffef748aff	1500437316584	9
00000000-0000-0030-ffff-ffffef748aff	1500437328388	10
00000000-0000-0030-ffff-ffffef748aff	1500437328548	11
00000000-0000-0030-ffff-ffffef748aff	1500437340583	12
00000000-0000-0030-ffff-ffffef748aff	1500448200225	13
00000000-0000-0030-ffff-ffffef748aff	1500448202219	14
00000000-0000-0030-ffff-ffffef748aff	1500448202987	15

根据这个结果，我们可以知道，尽管有相同的记录，row_number还是会根据order by字段依次递增编号，且编号不重复。

rank() OVER

sql如下

select
a.gu_id,starttime,
rank() OVER (partition by gu_id order by starttime) rn
from test.fct_path_list_off_5levels a
where a.date = '2017-07-19'
and gu_id = "00000000-0000-0030-ffff-ffffef748aff";

结果如下：

a.gu_id	starttime	rn
00000000-0000-0030-ffff-ffffef748aff	1500437284798	1
00000000-0000-0030-ffff-ffffef748aff	1500437284798	1
00000000-0000-0030-ffff-ffffef748aff	1500437285979	3
00000000-0000-0030-ffff-ffffef748aff	1500437286845	4
00000000-0000-0030-ffff-ffffef748aff	1500437287872	5
00000000-0000-0030-ffff-ffffef748aff	1500437290902	6
00000000-0000-0030-ffff-ffffef748aff	1500437291624	7
00000000-0000-0030-ffff-ffffef748aff	1500437298189	8
00000000-0000-0030-ffff-ffffef748aff	1500437316584	9
00000000-0000-0030-ffff-ffffef748aff	1500437328388	10
00000000-0000-0030-ffff-ffffef748aff	1500437328548	11
00000000-0000-0030-ffff-ffffef748aff	1500437340583	12
00000000-0000-0030-ffff-ffffef748aff	1500448200225	13
00000000-0000-0030-ffff-ffffef748aff	1500448202219	14
00000000-0000-0030-ffff-ffffef748aff	1500448202987	15

对比row_number 和 rank() OVER 的结果，可以发现，rank在处理相同的记录时候，编号是一样的，同时编号就不再连续，直到遇到有差异的记录。

Hive 官方文档

Hive LanguageManual+WindowingAndAnalytics

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