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Tuesday 18 June 2013

Informatica Interview Question and Answers

07:55
1.What is Data warehouse?

According to Bill Inmon, known as father of Data warehousing. “A Data warehouse is a subject oriented, integrated ,time variant, non volatile collection of data in support of management’s decision making process”.

2.What are the types of data warehouses?

There are three types of data warehouses
Enterprise Data Warehouse ODS (operational data store) Data Mart

3.What is Data mart?

A data mart is a subset of data warehouse that is designed for a particular line of business, such as sales, marketing, or finance. In a dependent data mart, data can be derived from an enterprise wide data warehouse. In an independent data mart can be collected directly from sources.

4.What is star schema?

A star schema is the simplest form of data warehouse schema that consists of one or more dimensional and fact tables.

5.What is snow flake schema?

A Snowflake schema is nothing but one Fact table which is connected to a number of dimension tables, The snowflake and star schema are methods of storing data which are multidimensional in nature.

6.What are ETL Tools?

ETL Tools are stands for Extraction, Transformation, and Loading the data into the data warehouse for decision making. ETL refers to the methods involved in accessing and manipulating source data and loading it into target database.

7.What are Dimensional table?

Dimension tables contain attributes that describe fact records in the fact table.

8.What is data Modelling?

Data Modeling is representing the real world set of data structures or entities and their relationship in their of data models, required for a database.

Data Modelling consists of various types like :
  • Conceptual data modeling
  • Logical data modeling
  • Physical data modeling
  • Enterprise data modeling
  • Relation data modeling
  • Dimensional data modeling.
9.What is Surrogate key?

Surrogate key is a substitution for the natural primary key. It is just a unique identifier or number of each row that can be used for the primary key to the table.

10.What is Data Mining?

A Data Mining is the process of analyzing data from different perspectives and summarizing it into useful information.

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