Wednesday, 4 February 2015

Technical Round BO Designer interview questions and answers (Part3)

21. What is Parse checking?
Parse checking means how DESIGNER is to determine the validity of an object, join, or condition.
• Quick parsing checks only the syntax of components.
• Thorough parsing checks both the syntax and semantics of components.

22. If there are changes in the database on which you have already created a universe, how do you include those additional changes into your universe?
By refreshing the structure I get the updated database structure.

23. What are Lookup and Fact Tables?
Lookup tables: A lookup (or dimension) table contains information associated with a particular entity or subject.
Fact Tables: A fact table contains statistical information about transactions.

24. What Types of Join Paths Return Incorrect Results?
1. Loops (Too few rows) 2. Fan Trap (Too many rows) 3. Chasm Trap (Too many rows)

25. What Are Loops?
In a relational database, a loop occurs when joins form multiple paths between lookup tables.

26. How to detect loops?
1) Run the Check Integrity function, which indicates the existence of any loops.
2) Select the Detect Loops command from the Tools menu.

27. How to resolve loops?
Loops can be resolved by creating aliases and contexts.

28. What is an Alias?
In SQL an alias is an alternative name for a table. In DESIGNER, an alias is just a pointer to another table. The purpose of aliases is to resolve structural issues in a database arising from SQL limitations. Whenever possible you should use an alias instead of a context.

29. What is a context?
Context is a method by which Designer can decide which path to choose when more than one path is possible from one table to another in the universe. Generally used transactional database with multiple Fact tables.
When you use a context, you expose the BO end user to the database structure. They are forced to decide which context they want to use to run their query. The role of the universe is to shield end users from the database structure, so they do not have to make such decisions.

30. What is Fan trap and Chasm Trap? How do you resolve?
Fan Trap: occurs when a “One to Many” join links a table which is in turn linked by another “One to Many” join.
There are two ways to solve Fan trap:
• Creating an alias and applying aggregate awareness function. This is the most effective way to solve the Fan trap problem.
• Using Multiple SQL statements for each measure.
Chasm Trap: occurs when two “Many to one” joins from two Fact tables converge on a single Lookup table.
Can be solved by:
• Creating a Context.
• Using Multiple SQL statements for each measure
• Creating multiple universes (WEBINTELLIGENCE only).
More Questions & Answers :-
Part1  Part2  Part3  Part4  Part5

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