hive正則表達(dá)式

• Hive中的正則表達(dá)式還是很強(qiáng)大的。數(shù)據(jù)工作者平時(shí)也離不開正則表達(dá)式。對(duì)此，特意做了個(gè)hive正則表達(dá)式的小結(jié)。所有代碼都經(jīng)過親測，正常運(yùn)行。

1.regexp

語法: A REGEXP B 
操作類型: strings 
描述: 功能與RLIKE相同

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

與下面查詢的效果是等效的：

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


2.regexp_extract

語法: regexp_extract(string subject, string pattern, int index) 
返回值: string 
說明：將字符串subject按照pattern正則表達(dá)式的規(guī)則拆分，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)


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)


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)


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)


hive> select regexp_replace("IloveYou","You","") from test1 limit 1;
Total jobs = 1
...
OK
Ilove
Time taken: 26.063 seconds, Fetched: 1 row(s)


3.regexp_replace

語法: regexp_replace(string A, string B, string C) 
返回值: string 
說明：將字符串A中的符合Java正則表達(dá)式B的部分替換為C。注意，在有些情況下要使用轉(zhuǎn)義字符,類似Oracle中的regexp_replace函數(shù)。

hive> select regexp_replace("IloveYou","You","") from test1 limit 1;
Total jobs = 1
...
OK
Ilove
Time taken: 26.063 seconds, Fetched: 1 row(s)



hive> select regexp_replace("IloveYou","You","lili") from test1 limit 1;
Total jobs = 1
...
OK
Ilovelili