hive正则表达式详解

梦里梦外; 2022-06-03 06:05 307阅读 0赞

hive中的正则表达式还是很强大的。数据工作者平时也离不开正则表达式。对此，特意做了个hive正则表达式的小结。所有代码都经过亲测，正常运行。

## 1.regexp ##

语法: A REGEXP B   
操作类型: strings   
描述: 功能与RLIKE相同

select count(*) from olap_b_dw_hotelorder_f where create_date_wid not regexp '\\d{8}'
     
      
       1

与下面查询的效果是等效的：

select count(*) from olap_b_dw_hotelorder_f where create_date_wid not rlike '\\d{8}';
     
      
       1

## 2.regexp\_extract ##

语法: regexp\_extract(string subject, string pattern, int index)   
返回值: string   
说明：将字符串subject按照pattern正则表达式的规则拆分，返回index指定的字符。

hive> select regexp_extract('IloveYou','I(.*?)(You)',1) from test1 limit 1;
    Total jobs = 1
    ...
    Total MapReduce CPU Time Spent: 7 seconds 340 msec
    OK
    love
    Time taken: 28.067 seconds, Fetched: 1 row(s)
     
      
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hive> select regexp_extract('IloveYou','I(.*?)(You)',2) from test1 limit 1;
    Total jobs = 1
    ...
    OK
    You
    Time taken: 26.067 seconds, Fetched: 1 row(s)
     
      
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hive> select regexp_extract('IloveYou','(I)(.*?)(You)',1) from test1 limit 1;
    Total jobs = 1
    ...
    OK
    I
    Time taken: 26.057 seconds, Fetched: 1 row(s)
     
      
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hive> select regexp_extract('IloveYou','(I)(.*?)(You)',0) from test1 limit 1;
    Total jobs = 1
    ...
    OK
    IloveYou
    Time taken: 28.06 seconds, Fetched: 1 row(s)
     
      
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hive> select regexp_replace("IloveYou","You","") from test1 limit 1;
    Total jobs = 1
    ...
    OK
    Ilove
    Time taken: 26.063 seconds, Fetched: 1 row(s)
     
      
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## 3.regexp\_replace ##

语法: regexp\_replace(string A, string B, string C)   
返回值: string   
说明：将字符串A中的符合java正则表达式B的部分替换为C。注意，在有些情况下要使用转义字符,类似oracle中的regexp\_replace函数。

hive> select regexp_replace("IloveYou","You","lili") from test1 limit 1;
    Total jobs = 1
    ...
    OK
    Ilovelili
     
      
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参考链接：   
1. [https://www.iteblog.com/archives/1639.html][https_www.iteblog.com_archives_1639.html] hive字符串处理函数，比较全

[https_www.iteblog.com_archives_1639.html]: https://www.iteblog.com/archives/1639.html