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.
In single sentence, it is repository of integrated information which can be available for queries and analysis.
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.
What is Dimension Table?
Dimension table is a table which contain attributes of measurements stored in fact tables. This table consists of hierarchies, categories and logic that can be used to traverse in nodes.
What is Fact Table?
Fact table contains the measurement of business processes, and it contains 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
What are the stages of Data warehousing?
There are four stages of Data warehousing:
·         Offline Operational Database
·         Offline Data Warehouse
·         Real Time Data warehouse
·         Integrated Data warehouse
What is Data Mining?
Data Mining is set to be a process of analyzing the data in different dimensions or perspectives and summarizing into a useful information. Can be queried and retrieved the data from database in their own format.
What is OLTP?
OLTP is abbreviated as On-Line Transaction Processing, and it is an application that modifies the data whenever it received and has large number of simultaneous users.
What is OLAP?
OLAP is abbreviated as Online Analytical Processing, and it is set to be a system which collects, manages, processes multi-dimensional data for analysis and management purposes.
What is the difference between OLTP and OLAP?
Following are the differences between OLTP and 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

What is ODS?
ODS is abbreviated as Operational Data Store and it is a repository of real time operational data rather than long term trend data.
What is Active Data warehousing?
An active data warehouse is a data warehouse that enables decision makers within a company or organization to manage customer relationships effectively and efficiently.
What is the difference between Data warehouse and OLAP?
Data warehouse is a place where the whole data is stored for analyzing, but OLAP is used for analyzing the data, managing aggregations, information partitioning into minor level information.
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.
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.
What is SCD?
SCD is defined as slowly changing dimensions, and it applies to the cases where record changes over time.
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
What is BUS Schema?
BUS schema consists of suite of confirmed dimension and standardized definition if there is a fact tables.
What is Star Schema?
Star schema is nothing but a type of organizing the tables in such a way that result can be retrieved from the database quickly in the data warehouse environment.
What is Snowflake Schema?
Snowflake schema which has primary dimension table to which one or more dimensions can be joined. The primary dimension table is the only table that can be joined with the fact table.
What is a core dimension?
Core dimension is nothing but a Dimension table which is used as dedicated for single fact table or data mart.
What is ETL?
ETL is abbreviated as 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. Next, it transform the data using rules and lookup tables and convert it to a desired state.
What is VLDB?
VLDB is abbreviated as Very Large Database and its size is set to be more than one terabyte database. These are decision support systems which is used to server large number of users.
What is real-time data warehousing?
Real-time data warehousing captures the business data whenever it occurs. When there is business activity gets completed, that data will be available in the flow and become available for use instantly.
What are Aggregate tables?
Aggregate tables are the tables which contain 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.
What is fact less fact tables?
A fact less fact tables are the fact table which doesn’t contain numeric fact column in the fact table.
How can we load the time dimension?
Time dimensions are usually loaded through all possible dates in a year and it can be done through a program. Here, 100 years can be represented with one row per day.
What are Non-additive facts?
Non-Addictive facts are said to be facts that cannot be summed up for any of the dimensions present in the fact table. If there are changes in the dimensions, same facts can be useful.
What is conformed fact?
Conformed fact is a table which can be used across multiple data marts in combined with the multiple fact tables.
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.
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