1. What is Data Warehousing?
A Data Warehouse is the repository of a data and it is used for Management decision support system. Data Warehouse consists of wide variety of data that has high level of business conditions at a single point in time or it is repository of integrated information which can be available for queries and analysis.2. What is Business Intelligence?
Business Intelligence is also known as DSS – Decision support system which refers to the technologies, application and practices for the collection, integration and analysis of the business related information or data. Even, it helps to see the data on the information itself.3. What is Dimension Table?
Dimension table contains of hierarchies, categories and logic which can be used to traverse in nodes and where measurements are stored in fact tables.4. What is Fact Table?
Fact table contains the measurement of business processes and foreign keys for the dimension tables.Example – If the business process is manufacturing of bricks Average number of bricks produced by one person/machine – measure of the business process
5. What is OLTP?
On-Line Transaction Processing is an application that modifies the data whenever it received and has large number of synchronized the users.6. What is OLAP?
Online Analytical Processing is a set of system which collects, manages, processes multi-dimensional data for analysis and management purposes.7. What is the difference between OLTP and OLAP?
Following are the differences between OLTP and OLAP:| OLTP | OLAP |
|---|---|
| Data is from original data source | Data is from various data sources |
| Simple queries by users | Complex queries by system |
| Normalized small database | De-normalized Large Database |
| Fundamental business tasks | Multi-dimensional business tasks |
8. What is ODS?
Operational Data Store is a repository of real time operational data rather than long term trend data.9. What is the difference between View and Materialized View?
A view is virtual table which takes the output of the query and it can be used in place of tables.A materialized view is an indirect access to the table data by storing the results of a query in a separate schema.
10. What is ETL?
The abbreviation of ETL is Extract, Transform and Load.ETL is a software which is used to reads the data from the specified data source and extracts a desired subset of data and transform the data using rules and lookup tables then convert it to a desired state and load function is used to load the resulting data to the target database.11. What is VLDB?
Very Large Database, size is set to be more than one terabyte database. These are decision support systems which is used to server large number of users.12. What is real-time data warehousing?
Real-time data warehousing captures the business data whenever it takes place. When the business activity is over , that data will be available in the flow and become available for use instantly.13. What are Aggregate tables?
Aggregate tables are the tables which carry the existing warehouse data which has been grouped to certain level of dimensions. It is easy to retrieve data from the aggregated tables than the original table which has more number of records.This table reduces the load in the database server and increases the performance of the query.
14. How can we load the time dimension?
Generally Time dimensions are loaded through a program by all possible dates in a year. Here, 100 years can be represented with one row per day.15. What is Data Mart?
A Data Mart is a specialized version of Data Warehousing and it contains a snapshot of operational data that helps the business people to decide with the analysis of past trends and experiences. A data mart helps to emphasizes on easy access to relevant information.16. What is Active Data Warehousing?
A warehouse that permits the decision makers within a company or organization to handle customer relationships effectively and efficiently is know as Active data warehouse .17. What is the difference between Data Warehouse and OLAP?
A place where the whole data is stored for analyzing is Data Warehouse but OLAP is used for analyzing the data, managing aggregations, information partitioning into minor level information.18. What is ER Diagram?
ER diagram is abbreviated as Entity-Relationship diagram which illustrates the interrelationships between the entities in the database. This diagram shows the structure of each tables and the links between the tables.19. What are the key columns in Fact and dimension tables?
Foreign keys of dimension tables are primary keys of entity tables. Foreign keys of fact tables are the primary keys of the dimension tables.20. What is SCD?
SCD is defined as slowly changing dimensions, and it applies to the cases where record changes over time.21. What are the types of SCD?
There are three types of SCD and they are as follows:SCD 1 – The new record replaces the original record
SCD 2 – A new record is added to the existing customer dimension table
SCD 3 – A original data is modified to include new data
