hadoop - Hive中的序列号UDF(Sequence Number UDF in Hive)

Question

i have tried this UDF in hive : UDFRowSequence .

(我已经在蜂巢中尝试了这个UDF： UDFRowSequence 。)
But its not generating unique value ie it is repeating the sequence depending on mappers.

(但是它没有产生唯一的值，即它根据映射器重复序列。)
Suppose i have one file (Having 4 records) availble at HDFS .it will create one mapper for this job and result will be like

(假设我在HDFS上有一个文件（具有4个记录），它将为此工作创建一个映射器，结果将是)
1

(1个)
2

(2)
3

(3)
4

(4)
but when there are multiple file (large size) at HDFS Location , Multiple mapper will get created for that job and for each mapper repetitive sequence number will get generated like below

(但是，当HDFS位置有多个文件（大文件）时，将为该作业创建多个映射器，并且将为每个映射器生成重复序列号，如下所示)
1

(1个)
2

(2)
3

(3)
4

(4)
1

(1个)
2

(2)
3

(3)
4

(4)
1

(1个)
2

(2)
.

(。)

Is there any solution for this so that unique number should be generated for each record

(有什么解决办法，以便为每个记录生成唯一的编号)

  ask by Elvish_Blade translate from so

Answer 1

I think you are looking for ROW_NUMBER() .

(我认为您正在寻找ROW_NUMBER() 。)

You can read about it and other "windowing" functions here .

(您可以在此处阅读有关它以及其他“窗口”功能的信息 。)

Example:

(例：)

SELECT *, ROW_NUMBER() OVER ()
FROM some_database.some_table