OBIEE Interview Questions and Answers |Oracle BI Interview Questions
Question.1 Define repository in terms of OBIEE?
Answer: Repository stores the Meta data information. The extension of the repository file is “.rpd”. With OBIEE Server, all the rules needed for security, data modeling, aggregate navigation, caching, and connectivity is stored in metadata repositories. Each metadata repository can store multiple business models. OBIEE Server can access multiple repositories
Repository is divided into three layer,
1. Physical – Represents the data Sources
2. Business – model the Data sources into Facts and Dimension and apply business logic
3. Presentation – Specifies the user’s view of the data rendered in OBIEE answers client
Question.2 What is the end to end life cycle of OBIEE?
Answer: OBIEE life cycle:
1. Gather Business Requirements
2. Identify source systems
3. Design ETL to load data to the Data Warehouse
4. Build a repository
5. Build dashboards and reports
6. Define security (LDAP or External table)
7. Based on performance, decide on aggregations and/or caching mechanism.
8. Testing and QA. [sociallocker]
Question.3 If you have 3 facts and 4 dimension and you need to join would you recommend joining fact with fact? If no than what is the option? Why you won’t join fact to fact?
Answer:Instead of joining fact with fact we can create one logical table (fact) and add the 3 fact tables as logical table source in the BMM layer.
Question.4 What is connection pool and how many connection pools did you have in your last project?
Answer:Connection pool is needed for every physical database.
It contains information about the connection to the database, not the database itself.
Can use either shared user accounts or can use pass-through accounts
We can have multiple connection pools for each group to avoid waiting
Question.5 What is the purpose of Alias Tables?
Answer:An Alias table is a physical table with the type of Alias. It is a reference to a physical table, and inherits all its column definitions and some properties from the physical table. A logical table source shows how the logical objects are mapped to the physical layer and can be mapped to physical tables, stored procedures and select statements. An alias table can be a reference to any of these logical table source types.
Alias Tables can be an important part of designing a physical layer. The following is a list of the main reasons to create an alias table:
1. To reuse an existing table more than once in your physical layer (without having to import it several times)
2. To set up multiple alias tables, each with different keys, names, or joins
3. To help you design sophisticated star or snowflake structures in the business model layer. Alias tables are critical in the process of converting ER Schemas to Dimensional Schemas.
Question.6 How do you define the relationship between facts and dimensions in BMM layer?
Answer: Using complex join we can define relationship between facts and dimensions in BMM layer.
Question.7 Did you create any new logical column in BMM layer, how?
Answer: Yes. We can create new logical column in BMM layer.
Example: Right click on fact table> select new logical column>give name for new logical column like Total cost.
Question.8 Can you use physical join in BMM layer?
Answer: Yes we can use physical join in BMM layer.
Question.9 Can you use outer join in BMM layer?
Answer: Yes we can. When we are doing complex join in BMM layer in the join properties we have an option to change the type of join to left outer, right outer, full outer or inner.
Question.10 What is level based metrics?
Answer: Level based metrics means, having a measure pinned at a certain level of the dimension.
A LBM is a metric that is defined for a specific level or intersection of levels.
Monthly Total Sales or Quarterly Sales are the examples.
Ex: if you have a measure called “Dollars”, you can create a “Level Based Measure” called “Yearly Dollars” which is Dollars for a Year. This measure will always return the value for the year even if you drill down to a lower level like quarter, month, etc. To create a level based measure, create a new logical column based on the original measure (like Dollars 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 Year in Time Dim.
Question.11 What is logging level? Where can you set logging levels?
Answer: You can enable logging level for individual users.
We can set the logging level based on the amount of logging you want to do. In normal operations, logging is generally disabled (the logging level is set to 0). If you decide to enable logging, choose a logging level of 1 or 2. These two levels are designed for use by Siebel Analytics Server administrators.
Set Logging Level:
1. In the Administration Tool, select Manage > Security.
2. The Security Manager dialog box appears.
3. Double-click the user’s user ID.
4. The User dialog box appears.
5. Set the logging level by clicking the up or down arrows next to the Logging Level field
Question.12 What are different types of variables? Explain each.
Answer:There are two classes of variables:
1. Repository variables
2. Session variables
A repository variable persists from the time the repository is started.
Static: This value does not change until a Siebel Analytics Server administrator decides to change it.
Dynamic: The values of these variables change with the values returned by queries. These variables are linked to an initialization block. An initialization block contains a SQL query. When the repository is started the value returned by the query in the initialization block will be assigned to the dynamic variable.
Session variables are created and assigned a value when each user logs on(when a new session is started). There are two types of session variables:
1. System: System variables have reserved names, which cannot be used for other kinds of variables (such as static or dynamic repository variables, or for non-system session variables).
Ex: To filter a column on the value of the variable LOGLEVEL set the filter to the Variable NQ_SESSION.LOGLEVEL.
2. Non-system: A common use of non-system variables is for setting user filters.eg:you could define a non-system variable called ‘SalesRegion’ that would be initialized to the name of the user’s sales region. You could then set a security filter for all members of a group that would allow them to see only data pertinent to their region. For example, to filter a column on the value of the variable ‘SalesRegion’ set the filter to the Variable NQ_SESSION.SalesRegion.
Question.13 What is Authentication? How many types of authentication do we have in OBIEE?
Answer:Authentication is the process by which a system verifies a user with the help of a user ID and password. It checks if user has the necessary permissions and authorizations to log in and access data. There are 4 main types of Authentication in OBIEE:
Operating system authentication
External table authentication
Question.14 What is object level security?
Answer:There are two types of object level security: Repository level and Web levelRepository level: In presentation layer we can set Repository level security by giving permission or deny permission to users/groups to see particular table or column.Web level: this provides security for objects stored in the OBIEE web catalog, such as dashboards, dashboards pages, folder, and reports you can only view the objects for which you are authorized. For example, a mid-level manager may not be granted access to a dashboard containing summary information for an entire department.
Question.15 What is data level security?
Answer: This controls the type or amount of data that you can see in a report. When multiple users run the same report the results that are returned to each depend on their access rights and roles in the organization. For example a sales vice president sees results for all regions, while a sales representative for a particular region sees data for that region.
Question.16 What is the difference between Data Level Security and Object Level Security?
Answer: Data level security controls the type and amount of data that you can see in a report. Object level security provides security for objects stored in the OBIEE web catalog like dashboards, dashboards pages, folder and reports.
Question.17 How do you implement security using External Tables and LDAP?
Answer: Instead of storing user IDs and passwords in a OBIEE Server repository, you can maintain lists of users and their passwords in an external database table and use this table for authentication purposes. The external database table contains user IDs and passwords, and could contain other information, including group membership and display names used for Siebel Analytics Web users.
Instead of storing user IDs and passwords in a OBIEE Server repository, you can have the OBIEE Server pass the user ID and password entered by the user to an LDAP(Lightweight Directory Access Protocol ) server for authentication. The server uses clear text passwords in LDAP authentication. Make sure your LDAP servers are set up to allow this.
Question.18 If you have 2 fact and you want to do report on one with quarter level and the other with month level how do you do that with just one time dimension?
Answer: Using level base metrics.
Question.19 If you want to create new logical column where will you create (in repository or dashboard) why?
Answer: It would be better if we create a new logical column in repository because if it is in repository you can use it for any report. If you create new logical column in dashboard then it is going to affect only those reports which are on that dashboard. We cannot use that new logical column for other dashboards.[/sociallocker]
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