Data Warehousing BO Interview Questions Answers.
Explain Strategies in Business Objects?Answer : A strategy is a script that automatically extracts structural information from a database or flat file. There are two types of strategies:
- Built-in strategies
- External strategies.
Answer : DESIGNER uses the following built-in strategies for creating the components of universes:
- The Objects Creation strategy, which tells DESIGNER how to define classes and objects automatically from the database’s tables and columns.
- The Joins Creation strategy, which tells DESIGNER how to define joins automatically from the database’s tables and
- The Table Browser strategy, which tells DESIGNER how to read the table and column structures from the database’s data dictionary.
Answer : In the external strategy file you can customize an existing strategy or create your own.
External strategy files are named according to the following convention:
StxxxxEN.txt where St means strategy, xxxx is an abbreviation for the RDBMS, and EN is the language in which Business Objects products are installed (EN =English)
For Oracle: Stora7en.txt in the Oracle folder
What is list mode in Business Objects?
Answer : List mode command (View ? List Mode) provides list of all the tables, joins, and contexts.
What do you mean by a join in BO?
Answer : A join is a relational operation that causes two or more tables with a common domain to be combined into a single table. The purpose of joins is to restrict the result set of a query run against multiple tables. DESIGNER supports: • Equi-joins • Theta joins • Outer joins • Shortcut joins Equi or Inner or Natural or Simple join: is based on the equality between the values in the column of one table and the values in the column of another.
Because the same column is present in both tables, the join synchronizes the two tables.
- Self-Join: join a table to itself i.e create a self-join to find rows in a table that have values in common with other rows in the same table.
- Theta or Non-Equi join: links tables based on a relationship other than equality between two columns.
- Outer join: links two tables, one of which has rows that do not match those in the common column of the other table.
- Left Outer Join: All records from first table with matching rows from second.
- Right Outer Join: All records from second-named table with matching rows from left.
- Full outer join: All rows in all joined tables are included, whether they are matched or not.
- Shortcut join: can be used in schemas containing redundant join paths leading to the same result, regardless of direction. Improves SQL performance.
Answer : Cardinality expresses the minimum and maximum number of instances of an entity B that can be associated with an instance of an entity A. The minimum and the maximum number of instances can be equal to 0, 1, or N. Cardinalities indicate whether the relationship or join between two tables is one-to-many (1,N), one-to-one (1,1), or many-to-many (N, N). Because a join is bi-directional, it must always have two cardinalities.
What do you mean by a Cartesian product ion BO?
Answer : A Cartesian product is the result of a query in which two or more tables are not linked by a join.
If executed, the report shows results for each possible combination of each table row.
Explain why you perform 'Integrity Check’ in Business Objects?
Answer :
- It detects any errors in the objects, joins, conditions, and cardinalities of your universe.
- It detects whether there are any loops in the joins.
- It detects whether contexts are necessary.
- It determines whether any changes were made to the database to which the universe is connected.
Answer : 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.
Answer : By refreshing the structure I get the updated database structure.
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