SAP-Business Objects_(DWH): BUSINESS OBJECTS ALL INTERVIEW QUESTIONS AND ANSWERS

1: Chasm trap:

The Chasm trap occurs when two “many to one” joins converge on a single table. For example a customer can place many orders/and or place many loans.

2: Fan trap

The Fan trap occurs when a “one to many” join links a table which is in turn linked by another “one to many” join.

4: Re: What are universe parameters? Answer

Definition Tab: name, description and connection to the

database

Summary Tab: author and statistics about the universe

Strategies Tab: internal or personal wizards to make

Creating a universe easier

Controls Tab: manages access and control of resources

SQL Tab: queries and SQL parameters

Links Tab: enables dynamic links with other universes.

5: Business Objects Universe Optimization

By BIDW Team on February 9, 2010

Every Business Objects Universe designer faces performance problems in his/her career at least once and in most of the cases he will use “push down strategy” ask DBA to optimize the warehouse

However it works very well

but there are some thing which can also help to optimize the performance of Universe.

Analyze Report SQL for unnecessary Joins

1. First get the list of reports which are performing low and get their SQL.

2. Analyze the report SQL for joins. There could be unnecessary join which is causing query to perform low. make a change in your universe accordingly to generate query with optimized joins.

Analyze report Query for Indexes. ( work with DBA for this )

1. Get the report SQL , check the where clause

2. Check if indexes are user properly in SQL and also they exist in database

3. Also, check if statistics in database is updated, as its its not then DB may not generate optimized query.

Use Aggregates for measures

1. Use Aggregate aware for your measure objects to use summary tables form Database

2. You can also think of Automatic Query re-write instead of using Aggregate Aware in Universe designer, However this requires careful planning and high involvement from DBA

Use Partitions for high volume fact tables

1. Partitioning the fact table can boost your query performance.

2. Work with DBA to get it done

Array Fetch Size

1. Play with Universe options for setting up optimal value of Array fetch Size parameter.

Universe Analysis for Shortcut joins

1. Analyze your reports and universe for possible use of shortcut joins as they play little but important role in performance.

Index Awareness

1. Try using Index Awareness from Universe side to generate optimized query.

Note: This requires thorough testing of report data and detail understating of data warehouse data

Universe Cleaning.

1. Make sure LOV is disabled measure objects

2. Make sure LOV is disable for un-necessary dimension objects

6-R WHAT IS ROW LEVEL SECURITY IN BO?

Answer

HI.. The above answer refers to Row limit where we can

restrict users to run reports for specific row limits like

5000 rows or 10000 rows just to have a good server

Performance.

Where Row level security is allowing the end user who runs

the report to view the data which he is authorized to view.

For Example you are trying to run a report which pulls data

contaings of 2 departments of the organization.

If you belong to DEP 1 then you will see data related to

DEP1 only and a user belonging to DEP2 can see DEP2 data

only. if you belong to both the groups then you can view

data without restrictions.

7-R: What are the different types of schemas?

Answer

two types of schemas r there: Star schema and snow flake Schema: in Snow flake schema normalozation is promoted where as in star schema denormalization is promoted. incase of snowflake schema DB size will be saved but no of joins will be increased and poor performance compare with star schemaregards,

8-R: Errors While Creating Univers?

The most common errors while creating universes are

cardinalities not ok
loops not ok
divergence not ok
check integrity not ok