Monday, December 24, 2012

OBIEE Interview Questions & Answers

 Define repository in terms of Siebel Analytics?

o Repository stores the Meta data information. Siebel repository is a file system ,extension of the repository file. rpd.
o META DATA REPOSITORY
o With Siebel Analytics Server, all the rules needed for security, data modeling, aggregate navigation, caching, and connectivity is stored in metadata repositories.
o Each metadata repository can store multiple business models. Siebel Analytics Server can access multiple repositories

What is the end to end life cycle of Siebel Analytics?

o Siebel Analytics life cycle
1. Gather Business Requirements
2. Identify source systems
3. Design ETL to load to a DW if source data doesn’t exist.
4. Build a repository
5. Build dashboard or use answers for reporting.
6. Define security (LDAP or External table…)
7. Based on performance, decide on aggregations and/or caching mechanism.
8. Testing and QA.
What were you schemas? How does Siebel Architecture works? Explain the three layers. How do you import sources?

o There are five parts of Siebel Architecture.
1. Clients
2. Siebel analytics Web Server
3. Siebel analytics server
4. Siebel analytics scheduler
5. data sorces
o Metadata that represents the analytical Model Is created using the siebel Analytics Administration tool.
o Repository divided into three layer
1. Physical – Represents the data Sources
2. Business – models the Data sources into Facts And Dimension
3. Presentation – Specifies the users view of the model;rendered in Siebel answer

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?

 In the BMM layer, create one logical table (fact) and add the 3 fact table as logical table source

 What is connection pool and how many connection pools did you have in your last project?

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 -Use: USER and PASSWORD for pass through .
 We can have multiple connection pools for each group to avoid waitin

 Purpose of Alias Tables?

 
An Alias table (Alias) is a physical table with the type of Alias. It is a reference to a logical table source, and inherits all its column definitions and some properties from the logical table source. 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:
  To reuse an existing table more than once in your physical layer (without having to import it several times)
  To set up multiple alias tables, each with different keys, names, or joins
  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.

How do you define the relationship between facts and dimensions in BMM layer?


 Using complex join ,we can define relationship between facts and dimentions in BMM layer.

 What is time series wizard? When and how do you use it?

We can do comparison for certain measures ( revenue.,sales etc.. ) for current year vs previous year, we can do for month or week and day also
 Identify the time periods need to be compared and then period table keys to the previous time period.
 The period table needs to contain a column that will contain “Year Ago” information.
 The fact tables needs to have year ago totals.
 To use the “Time series wizard”. After creating your business model right click the business model and click on “Time Series Wizard”.
The Time Series Wizard prompts you to create names for the comparison measures that it adds to the business model.
 The Time Series Wizard prompts you to select the period table used for the comparison measures
 Select the column in the period table that provides the key to the comparison period. This column would be the column containing “Year Ago” information in the period table.
Select the measures you want to compare and then Select the calculations you want to generate. For ex: Measure: Total Dollars and calculations are Change and Percent change.
 
Once the Time series wizard is run the output will be:-
a) Aliases for the fact tables (in the physical layer)
b) Joins between period table and alias fact tables
c) Comparison measures
d) Logical table sources
o In the General tab of the Logical table source etc you can find “Generated by Time Series Wizard” in the description section
o Then you can add these comparision measures to the presentation layer for your reports.
o Ex: Total sales of current qtr vs previous qtr vs same qtr year ago

 Did you create any new logical column in BMM layer, how?

o Yes. We can create new logical column in BMM layer.
o Example: Right click on fact table -new lgical column-give name for new logical column like Total cost.
o Now in fact table source,we have one option column mapping, in that we can do all calculation for that new column.
Can you use physical join in BMM layer?

 yes we can use physical join in BMM layer.when there is SCD type 2 we need complex join in BMM layer.

Can you use outer join in BMM layer?

 yes we can.When we are doing complex join in BMM layer ,there is one option type,outer join is there.

 What are other ways of improving summary query reports other than Aggregate Navigation and Cache Management


Indexes
Join algorithm
Mat/view query rewrite
Web proper report design its optimal by making sure that it is not getting any addition column or rows

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