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Sunday, 25 November 2012

OBIEE Interview Questions & Answers


OBIEE Interview Questions & Answers

1. Explain the Architecture of OBIEE and what each components do?
Answer :- OBIEE Consists of Presentation Services(Web),Oracle BI (Analytics Engine) Server
The client (Answers) constructs sql and passes it to the Analytic Engine and then the Oracle BI (Analytic Engine) parses the physical sql to the Datasources and retrieve the data back to the Engine and presents to the presentation Services .

2. How to get sql from obiee for reports?
Answer :- There are many ways to get the sql
a. Modify the request and click Advanced in that you get xml code and also the actual sql.
b. In the catalog Manager click Tools –>Create Report .In the Create Report Window –> Click Request SQL and save the sql to the physical path in your PC.
c. Enable Loglevel to 2 in the OBIEE Admin Tool from Mange-> Security and enable the log level to 2 by clicking properties for the user, then go to the NQQuery.log in BI_HOME/OracleBI/Server/Logs.You will find the SQL for that User.
d. By clcking Administration->Manage sessions-> view sql.

3.  How will you do sort in Reports in OBIEE Answers.
Answer :- Click modify and then click sort (order by icon) on the relevant column in the criteria pane.

4.  How will you do different types of narrative Reports in OBIEE?
Answer:- By clicking modify request and Narrative View and by giving @1 for the first column result and @2 for the 2nd column and son on and we can also give a heading for No Results by clicking the Narrative view.

5. How will you create Interactive Dashboards ?
Answer:- By clicking Administration and Manage dashboards and by adding column selector also by using view selector etc.and also by using prompts.

6. What is write-back in obiee ?
Answer:- In Reports of Answer you can give a column as updatebale and then view the reports,this option is called write back.

7. How will you execute Direct SQL in OBIEE?
Answer:- By clicking Direct Database Request below the subject area in Answers.

8. How will you create report from two subject areas
Answer:- From the Criteria Pane of the Report Created from First Subject Area
come to the bottom of the page and click combine request. but the options are limited for combining like union etc..

9. How will you Port changes for dashboards,reports,rpd from development to production?
Answer:- For the RPD use the Merge option in Admin Tool and for dashboards and reports use Content Accelerator Framework.

10. What are the different types of variables in OBIEE? explain
Answer:- There are two types of variables in obiee.
a.Repository variable.
This variable is for the whole repository.
b.session variable . session variable can be system variable and non system variable. system variable uses NQ_SESSION. —- (system reserved variable). examples of non system variables are user defined filters etc.

11. How will you enable or disable caching in the system level and table level?
Answer:- In the NQSConfig.ini file use ENABLE under CACHE Section for System Level
for tables .If you want to enable the cache at table level , open the repository in offline mode(not the current working repository). this should be different from the current repository and click enable or disable the cache . right click the table and properties and click the cache or deselect the cache. then merge the repository with the current working one.

12. How will you go about adding additional column to the repository in the presentation layer?
Answer :- Check whether the table is already existing if so add in physical layer ,then BMM and then Presentation layer, then reload server metadata ,then it will be visible to all users.

13. How will effect the changes for a report , if for certain users only the column heading in the report should be changed?
Answer:-  Using session variables for that user.

14. What is a table alias in obiee? and where and how will you create it.
Answer:- Table alias can be created by right clicking the table in the physical layer then click alias,
Table alias is mostly used for creating self joins.

15. Have you created Hierarchy in OBIEE. if so where and how?
Answer:- Yes we can create hierarchy in BMM Layer of OBIEE in dimensions for the dimension tables. this can be done by right clicking the dimension table and click create dimension and then we should manually define the hierarchy and its levels.

16. What is Level Based Metrics.How will you create it?
Answer:- Leval-base matrics means, having a measure pinned at a certain level of the dimension. Monthly Total Sales or Quarterly Sales are the examples.
To create a level based measure, create a new logical column based on the original measure (like Sales in the example above). Drag and drop the new logical column to the appropriate level in the Dimension hierarchy (in the above example you will drag and drop it to Month in Time Dimension.

17. What are the different layers of OBIEE Repository?
Answer:- Physical Layer, Business Model and Mapping Layer, and Presentation Layer.

18. What is Authentication? How many types of authentication.
Answer:- Authentication is the process by which a system verifies, through the use of a user
a. Operaing system autentication
b. External table authentication
c. Database authentication
d. LDAP authentication

19. What are the different types of security you have worked in OBIEE?
Answer :- Object Level and data level.

20. What is a bridge table ?
Answer:- If you want to connect two tables where there is no relation ship you can use a thrid bridge table for connecting them which will have common columns in both tables, this is used in BMM Layer.

21. You come Morning to the office. and all the users are complaining about the obiee reporting system is very slow(dasboards). what is your approach to resolve the issue?
Answer:- Mainly check NQServer.log and in Admin Tool -> click Session Manager. check if there is any bottleneck and accordingly resolve.

22. What are the different log files in OBIEE?
Answer:- Following are the different log files inOBIEE
               NQServer.log , NQQuery.log, NQSAdminTool.log etc.
               There are mainly 25 Configuration files available in obiee.

23. What are the Key Configuration Files in OBIEE?
Answer:- NQSConfig.ini, NQSCluster.ini, odbc.ini, instanceconfig.xml

24. How will change port of obiee answers?
Answer:- By changing its port in instanceconfig.xml

25. What is ClusterServices in OBIEE ? Why its used?
Answer:- To Scale up the Performance by clustering and distributing the services across multiple Servers ClusterServices are used.

26. Can you change the location of the OBIEE Repository?
Answer:- No, Not in Standalone OBIEE Install. you can give shared location in NQSCluster.ini if the OBIEE is clustered.

27. How many BI Services Node can be clustered together?
Answer :- 16

28. Can you run multiple rpd’s in a Single OBIEE Instance?
Answer :- No . you should create another instance in the same server , then its possible.

29. How will you implement security in obiee,so that subjects areas accessed by one group are not accessed by another group.
Answer:- Using Security Manger in OBIEE Admin Tool, by creating two user groups and allowing only part of the subject area for one group and other part to the other user group.

30. What is SCD type 1 and 2.
Answer:- SCD is slow changing dimensions. in type 1 we replace the changed dimension with old dimension. in type 2 we use surrogate keys and keep both the records(rows). Advantage of SCD2 is we keep history of the old dimensiont.

31. What is Star Schema and SnowFlake Schema?
Answer:- Star is one fact and many dimensions where as Snowflake design is one fact and many dim’s and dim’s can have additonal dim relations.

32. How to startup OBIEE in Linux?
Answer:-
./run-sa.sh start #starts obi server
./run-saw.sh start #start saw server
./run-sch.sh start #start scheduler

33. How you generally Approach to ur Analytics Project?
Answer:- Any project should start from defining the scope of the project and the approach
should be not to deviate from the scope.
Then the project should be functionally divided into smaller modules generally done by
project managers along with technical and functional leads.
The functional leads then decide on majorly three things:
  1. According to the defined scope of the project they start gathering requirements while interacting with the clients.
  2. They had a discussion with the technical leads and try to reach a solution.
  3. Technical leads decides what schemas to create and what requirements are going to fulfill by that schema.
Technical leads discuss all this with the developers and try to close requirements.
Simultaneously testing and deployment is planned in a phased manner.

34. How we are going to decide which schema we are going to implement in the data warehouse? 
Answer:- One way is what is mentioned in Question above.
If one ask you to blindly create schemas for the warehouse without knowing any requirements,
You can simply first divide the schemas on the basis of functional areas of an Organization which are similar to the modules in an ERP like sales, finance, purchase, inventory, production, HR etc.
You have to broadly describe the expected analysis an organization would like to do in every module. This way you would be able to complete at least 40-50 % of the requirements. To move ahead, study the data and business and you can create few more schemas.

35. What are the Challenges You Faced while making of Reports?
Answer:- Making of an report has never been a difficult task. But problem comes when users are reluctant to adopt a new system. Many developers have experienced that if they are not able to create the report in exactly the way they used to see, they will keep asking for the changes. Developers approach should be to first show them what they want to see and then add more information in the report.

36. What you will do when your Report is not Fetching Right Data?
Answer:- This is the biggest problem in report creation and verification. There could be two reasons for report not fetching the right data.
1. Mostly clients do not have correct data in their database and on top of that to correct the results they make some changes at the report level to bring the desired result which you may not e aware of while creating the reports. Clients try to match the data with their existing reports and you never get the correct results. you try to discover the things and at later stage come to know of all these problems and you are held responsible for this delay. Hence always consult the SPOC(Single Point of Contact) and try to understand the logic they have used to generate their reports.

2. If the database values are correct, there there could be a problem with the joins and relations in the schema. You need to discover that analyzing and digging deep into the matter.

37. How analytics Process Your Request When you Create your Requests?
Answer:- Oracle BI server converts the logical SQL submitted by the client into optimised physical SQL which is then sent to the backend database. Also in between it performs various tasks like converting the user operations like user selections to form a logical SQL, checking and verifying credentials, breaking the request into threads(as Oracle BI is a multi threaded server), processes the requests, manages the cached results, again converting the results received from the database into user presentable form etc.

38. From where u Get the Logical Query of your Request?
Answer:- The logical SQL generated by the server can be viewed in BI Answers.

39. What are the Major Challenges You Faced While Creating the RPD??????
Answer:- Every now and then there are problems with the database connections but the problem while creating the repository RPD files comes with complex schemas made on OLTP systems consisting of lot of joins and checking the results. Th type of join made need to be checked. By default it is inner join but sometimes the requirement demands other types of joins. There are lot of problems with the date formats also.

40. What are Global Filter and how thery differ From Column Filter?
Answer:-
Column filter- Simply a filter applied on a column which we can use to restrict our column values while pulling the data or in charts to see the related content.
Global filter- This filter will have impact on across the application.

41. How to hide Certain Columns From a User?

Answer:-
 We can hide a column in Application access level security
Do not add the column in the report
Do not add the column in the presentation layer.

42. How to Enable Drills in a Given Column Data?
Answer:- To enable Drill down for a column, it should be included in the hierarchy in OBIEE.
Hyperion IR has a drill anywhere feature where dont have to define and can drill to any available column.


43. How the users Created Differs From RPD/Answers/Dashboards Level?
Answer:- RPD users can do administrator tasks like adding new data source, create hirarchies, change column names where as Answers users may create new charts, edit those charts and Dashboard users may only view and analyse the dashboard or can edit dashboard by adding/removing charts objects.

44. How Online/Offline mode impact Development and Delpoyment????
Answer:-
Online Mode- You can make changes in the RPD file and push in changes which will be immediately visible to the users who are already connected. This feature we may use in production environment.
Offline mode- can be useful in test or development environment.

45. What is Guided Navigation?
Answer:- Guided navigation is a feature of Oracle BI Interactive Dashboards that enables the content and layout of Oracle BI Interactive Dashboard to change dynamically based on changes in the information being analyzed.
Specifically, sections in a dashboard page can be set up and only appear when there is “interesting” information in the data.

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