In computing, a data warehouse (DW or DWH), also known as an enterprise data warehouse (EDW), is a system used for reporting and data analysis, and is considered as a core component of Business Intelligence environment. DWs are central repositories of integrated data from one or more disparate sources.a data warehouse (DW or DWH), also known as an enterprise data warehouse (EDW), is a system used for reporting and data analysis, and is considered as a core component of Business Intelligence [1] environment. DWs are central repositories of integrated data from one or more disparate sources. They store current and historical data and are used for creating analytical reports for knowledge workers throughout the enterprise. Examples of reports could range from annual and quarterly comparisons and trends to detailed daily sales analysis. The data stored in the warehouse is uploaded from the operational systems (such as marketing, sales, etc., shown in the figure to the right). The data may pass through an operational data store for additional operations before it is used in the DW for reporting.

1. Presentation Prepared by:
Vikram

2. Who are my customers
and what products
are they buying?
Which are our
lowest/highest margin
customers ?
What product prom-
-otions have the biggest
impact on revenue?
What is the most
effective distribution
channel?

3. A single, complete and consistent store of
data obtained from a variety of different
sources made available to end users in a
what they can understand and use in a
business context.

4.  A process of
transforming data
into information and
making it available to
users in a timely
enough manner to
make a difference
Data
Information

5.  Subject Oriented
 Integrated Data
 Time-Variant Data
 Nonvolatile Data

8.  Allows for analysis of the past
 Relates information to the present
 Enables forecasts for the future.

15. Feature OLTP OLAP
Characteristics Operational processing Informational processing
Orientation Transaction Analysis
User Clerk, DBA, database professional Knowledge worker(e.g. managers)
Function Day-to Day operations Long-term informational
requirements, decision support
DB Design ER based, application-oriented Star/Snowflake, subject-oriented
Data Current; guaranteed up-to-date Historical; accuracy maintained over
time
Summarization Primitive, highly detailed Summarized, consolidated
View Detailed Summarized
Unit of Work Short, simple transaction Complex query
Access Read/write Mostly read
Focus Data in Information out
Operations Index/hash on primary key Lots of scan
DB Size 100 Mb to Gb 100 Gb to Tb
Priority High performance, High availability High flexibility, end-user autonomy
Metric Transaction throughput Query throughput
Number of Users Thousands Hundreds

16. 16
Data Warehouse Server
(Tier 1)
Data
Warehouse
Operational
Data Bases
Semistructured
Sources Query/Reporting

Data Marts
MOLAP
ROLAP
Clients
(Tier 3)
Tools
Meta
Data
Data sources
Data
(Tier 0)





IT
Users


Business
Users


Business Users
Data Mining

Archived
data
Analysis

OLAP Servers
(Tier 2)
Extract
Transform
Load
(ETL)
www data
Data Warehousing Components

17.  Consider, we want to create operational
system for order processing department of a
company.
 Users can easily define the requirements as:
◦ How they receive the orders
◦ Check stock
◦ Verify customers credit arrangements
◦ Price the order
◦ Determine shipping arrangements
◦ Route the order to the appropriate warehouse
◦ GUI they use for processing
◦ How and when they use the application

18.  Even though the users cannot fully describe what
they want in a data warehouse, they can provide
you with very important insights into how they
think about the business.
 They can tell you what measurement units are
important for them.
 Each user department can let you know how they
measure success in that particular department.
 The users can give you insights into how they
combine the various pieces of information for
strategic decision making.

20. Client
Warehouse
Source
Source
Query & Analysis
Integration
Metadata
Source
Client