General Questions:
1. What is a data-warehouse?
A datawarehouse is a repository(centralized as well as distributed) of Data ,able to answer any adhoc,analytical,historical or complex queries.
It contains 3 types of data
2. What are Data Marts?
Data mart is a subset of a datawarehouse.
4. What is ER Diagram?
It represents entities and relationshiup between then in a domain
5. What is a Star Schema?
It has a centralized fact table ,reprensenting the facts on the intersection of the dimensions directly pointing to the fact table.
6. What is Dimensional Modelling?
Breakup of standard Normilised data between ever changing fact(Numeric informal data) and slowly changing or fixed non numeric data for fast and effective OLAP
7. What Snow Flake Schema?
in snowflake schema dimensions pointing to fact tables itself are pointed by sub dimension tables.
8. What are the Different methods of loading Dimension tables?
Depends on Dimension type
For static dimensions one time or periodical loading can be done
For slolwy changing dimensions
1.Overwrite : but u will lost the historical aspect of dw
9. What are Aggregate tables?
These are the fact tables which do note represent the lowest granujlarity level
People do it when minut info is not needed and fast processing is required
10. What is the Difference between OLTP and OLAP?
Online Transaction Processing : Lowest Granularity,continuous update,transaction data,slow reporting
Made for fast insert,up;date,delete
OnLine Analytical Processing: Varying Granularity,Batch Update,Historical data ,Fast reporting..
Made for fast reporting
11. What is ETL?
Extraction,Transformation,Loading
12. What are the vaious ETL tools in the Market?
DTS,Informatica,Decision Stream?
13. What are the various Reporting tools in the Market?
Hyperion Essbase(earlier Brio),Analysis service,Cognos,Beacon?.
14. What is Fact table?
Represents the numeric data of a data mart ,representing data on the intersection of related dimensions..
15. What is a dimension table?
Non numeric data of the domain on the hierarchy of which aggregation or segregation of fact is needed
16. What is a lookup table?
Represents metadata
17. What is a general purpose scheduling tool? Name some of them?
use in scheduling yaar,..say window scheduler/cognos scheu or upfront schedular.
18. What are modeling tools available in the Market? Name some of them?
Analysis services,Architect(cognos)
19. What is real time data-warehouse
20. What is data warehouse and why should we go for and what are advantages and disadvantages?
21. What is metadata?
22. Difference between star schema and snowflake schema?
23. What is dimensional modeling and why we need to go for it.
24. What is normalization and how many types of normal forms are there?
25. What is data mining?
26. Difference between OLAP and OLTP?
28.What is fact less fact table?
29. What are casual dimensions and confirmed dimensions?
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