Hive Virtual columns examples

Step1:
Inside Files directory:
[cloudera@quickstart files]$ ls -ltr
total 8
-rw-rw-r-- 1 cloudera cloudera 6 Apr 15 10:56 file11.txt
-rw-rw-r-- 1 cloudera cloudera 8 Apr 15 10:57 file12.txt
Sample Data's
[cloudera@quickstart files]$ cat file11.txt
1
2
3
[cloudera@quickstart files]$ cat file12.txt
3
5
6
7

Step 2:
Create the hive table:
hive>; create external table tab(id Int) row format delimited fields terminated by ',' location 'file:///home/cloudera/files/';
OK
Time taken: 0.043 seconds

Step 3: Execute in hive
hive> select id,INPUT__FILE__NAME from tab;
OK
3 file:/home/cloudera/files/file12.txt
5 file:/home/cloudera/files/file12.txt
6 file:/home/cloudera/files/file12.txt
7 file:/home/cloudera/files/file12.txt
1 file:/home/cloudera/files/file11.txt
2 file:/home/cloudera/files/file11.txt
3 file:/home/cloudera/files/file11.txt
INPUT__FILE__NAME--It is the virtual column name in hive

hive>;; select id,REGEXP_EXTRACT(INPUT_FILE_NAME, './(.)/(.*)', 2) as FILE_NAME from tab;
OK
3 file12.txt
5 file12.txt
6 file12.txt
7 file12.txt
1 file11.txt
2 file11.txt
3 file11.txt
Time taken: 0.052 seconds, Fetched: 7 row(s)

hive>;; create view emp_upd as select id,REGEXP_EXTRACT(INPUT_FILE_NAME, './(.)/(.*)', 2) as FILE_NAME from tab;
OK
Time taken: 0.11 seconds
hive>; select * from emp_upd;
OK
3 file12.txt
5 file12.txt
6 file12.txt
7 file12.txt
1 file11.txt
2 file11.txt
3 file11.txt
Time taken: 0.096 seconds, Fetched: 7 row(s)