Thursday, May 27, 2010

Basic concepts- Microstrategy Interview Question and Answers

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What is ROLAP and MOLAP? Is MicroStrategy a ROLAP or MOLAP tool?

ROLAP (Relational online Analytical Processing) tools do not use pre-calculated data cubes. Instead, they intercept the query and pose the question to the standard relational database and its tables in order to bring back the data required to answer the question

MOLAP (Multidimensional online Analytical Processing) tools utilize a pre-calculated data set, commonly referred to as a data cube, that contains all the possible answers to a given range of questions.

MicroStartegy is ROLAP tool.


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What is star schema and snowflake schema?

Star Schema is a highly denormalized schema whereas snowflake schema is hight normalized schema.Star schema is characterized by large number of rows in a table and less number of joins between tables.Snowflake schema is characterized by less number of rows in a table while more number of joins between tables.


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What are the advantages and disadvantages of star and snowflake schema?

Star Schema Advantages: Reduces the number of joins between the tables and hence faster performance

Star Schema Disadvantages:Requires Most amount of storage space.

Snowflake Schema Advantages: Minimum storage space and minimum data redudancy

Snowflake Schema Disadvantages:Requires more joins to get information from look up tables hence slow performance.


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What is the difference between 2 tier,3 tier and 4 tier architecture in MicroStrategy?

In 2 tier architecture, the MicroStrategy Desktop itself queries aganist the Data warehoue and the Metadata with out the Intermediate tier of the Intelligence server.

The 3 Tier architecture comprises a Intelligence server between MicroStrategy Desktop and the data Warehouse and the Metadata.

The 4 tier architecture is same as 3 tier except it has a additional component of MicroStratey Web.


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What are adhoc reports and static reports?
Adhoc reports run in real time based on the input parameters provided by the user at the run time.In Microstrategy, adhoc reports are created using Prompts.

In static reports, users won't be provide any input parameters.These reports are usaully schedule to run overnight and ready to view immediatley in the mornings using cache.


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www.allwalkin.blogspot.comWhat is a filter?

Filter is a public object.It is used to restrict the data retrived by the report from the database tables.From SQL perspective it corresponds to the "WHERE" Clause.


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What are VLDB properties?

Using VLDB properties we can change the way how the SQL is generated.Some of them are below:

Perform full outer joins
Check for Zeros and Nulls in the denominator while performing divisions in Metrics.
Creating Sub queries
Creating temperory tables.


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What are Consolidations?
Consloidations enable to group together attibute elements and create a virtual attribute.They perform Row level maths.


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What are custom groups?

Custom groups are used to create different filters to different rows of a report.For example, a report can created to display top 5 customers as well as bottom 5 customers in the one report using custom group.


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What are Passthrough Functions?

Pass through functions are used to utilize various special functions that specific to databases.Some of the passthrough functions available are Applysimple and Applycomparision.


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What is a Security filter?
Security filter is used to apply security at the database data level.Whenever a users associated with security filter runs a report, a WHERE clause is always included in the report sql with the condition defined in the Security Filter.


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Is that possible to Insert and Update a record in the Database through Microstrategy?
Answer-1:
You can do so by ODBC test tool one of the component of microstrategy through wich u can update delete or even alter the table specification as per your need.


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In Microstrategy, how can you direct the sql generated to use a specifc table?
Answer-1:
By changing the Logical Size of the "specific" table.
After changing table size, you need to update schema.


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In Microstrategy, what are Logical Views used for?
Answer-1:
A logical view is a view that u obtain by querying the db thru sql. these result can be stored as a table then.


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In Microstrategy, how can you direct the sql generated to use a specifc table?
Answer-1:
Using the Level parameter in the Metric level options

Answer-2:
Assuming you have OLAP licence,the easiest way to direct to a particular table is to create a dummy fact on the table,include the fact in metric and put the metric in report objects
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