who are fathers of data warehousing?

Bill Inmon and from Ralph Kimball,the fathers of data warehousing:

• According to Bill Inmon, a data warehouse is a subject-oriented, integrated, nonvolatile,and time-variant collection of data in support of management’s decisions.

• According to Ralph Kimball, a data warehouse is a system that extracts, cleans, conforms, and delivers source data into a dimensional data store and then supports and
implements querying and analysis for the purpose of decision making.


Both of them agree that a data warehouse integrates data from various operational source systems. In Inmon’s approach, the data warehouse is physically implemented as a normalizeddata store. In Kimball’s approach, the data warehouse is physically implemented in a dimensional data store.

what is Business Intelligence?

Business intelligence is a collection of activities to understand business situations by performing various types of analysis on the company data as well as on external data from third parties to help make strategic, tactical, and operational business decisions and take necessary actions for improving business performance. This includes gathering, analyzing,understanding, and managing data about operation performance, customer and supplier activities, financial performance, market movements, competition, regulatory compliance, and quality controls

what is normalization?

Normalization is a process of removing data redundancy by implementing normalization
rules. There are five degrees of normal forms, from the first normal form to the fifth normal form.

list schemes used in implementaiton of Dimensional data store?

Dimensional data store(DDS) can be implemented physically in the form of several different
schemas.

Some examples of dimensional data store schemas are a

star schema
a snowflake schema,
and a galaxy schema.

In a star schema, a dimension does not have a subtable (a subdimension).

In a snowflake schema, a dimension can have a subdimension. The purpose of having a subdimension is to minimize redundant data.

A galaxy schema is also known as a fact constellation schema. In a galaxy schema, you have two or more related fact tables surrounded by common dimensions

what is dimensional data store (DDS)?

A DDS is a database that stores the data warehouse data in a different format than OLTP.

The reason for getting the data from the source system into the DDS and then querying the DDS instead of querying the source system directly is that in a DDS the data is arranged in a dimensional format that is more suitable for analysis.

The second reason is because a DDS contains integrated data from several source systems.

and we can take risk of querying source systems... source systems may go down

what is data profiler?

A data profiler is a tool that has the capability
to analyze data, such as finding out how many rows are in each table, how many rows
contain NULL values, and so on.

what is OLTP System?

Online Transaction Processing (OLTP) is a system whose main purpose is to capture
and store the business transactions