Datastage Interview Questions

Datastage Interview Questions

1. What is configuration file?

APT configuration file contains details of node. In this it has sub parts node, pool, scratch disk, resource disk

2. What is difference between join, lookup ?

Join---(a) does not support reject link,

            (b)  in this link name are left, right, intermediate, 

            ©   supports inner join, left outerjoin, right outerjoin, full outerjoin

Lookup-(a) supports reject link

               (b) in this link names are   primary, reference

               © supports inner join (called as drop) left outer join(continue)

3. What is dataset?

Dataset is file stage with extension .ds.  in this data is stored in descriptor file and data fiile.

To retrieve data from dataset from unix “ orchadmin command is used.

4. What are different types of portioning techniques?

Key based portioning—hash,modulus,range

Key less portioning---- same,auto

5. How to remove duplicates in datastage?

REMOVE DUPLICATE STAGE.

IN COPY STAGE( IN THIS GO TO INPUT--- PARTIONINS-CHANGE TO HASH PARTIONS-CHECK SORT- UNIQUE(THIS UNIQUES REMOVE DUPLICATES)

SORT STAGE AND TRANSFORMER STAGE--- KEY CHANGE COLUMN SET TO TRUE(THIS IS DONE IN SORT STAGE)—TRANSFORMER STAGE(CONSTARINT)

6. What is difference between active stage and passive stage?

Active stages- all processing stages are active(transformation part)

Passive stage- file stage,database stage.

7. How to  handle unix commands in sequential file? What other stages supports unix command?

In sequential file stage there is options—in that slect filter(here we can write unix) and change the file method to file pattern. 

External filter stage supports unix command

8. Difference between filter and switch?

Switch is used to write case statement and we can do on single coulumn

Fileter is used to write where clause and we can do on multiple columns

9. How to find nth maximum salary from emp?

 In oracle select * from ( select sal,empid,rownum over(order by sal desc) rn from emp) where rn=-2

10. How to remove duplicates from table?

11. Difference between union and union all?

Union- remove duplicates

Union all- with duplictaes

12. How to delete nth line in unix?

Sed nd

13. Where/Group by/having/ based scenario?

SELECT Salesperson, SUM(TotalSale)

FROM SALES

GROUP BY Salesperson

HAVING Salesperson <>'Bennett';

14. how to replace one string with another in unix?

Sed ‘s\ old string\ new string’  filename

15. how to remove duplicates in a file through unix

   Uniq command