OLAP & DATA WAREHOUSE

OLAP (Online Analytical
Processing)
By
Zalpa Rathod (39)
Yatin Puthran (37)
Mayuri Pawar (35)
Mitesh Patil (33)

OVERVIEW
 INTRODUCTION
 OLAP CUBE
 HISTORY OF OLAP
 OLAP OPERATIONS
 DATAWAREHOUSE
 DATAWAREHOUSE
ARCHITECHTURE
 DIFFERENCE BETWEEN OLAP &
OLTP
 TYPES OF OLAP
 APPLICATIONS OF OLAP

INTRODUCTION TO OLAP
 OLAP (online analytical processing) is
computer processing that enables a
user to easily and selectively extract and
view data from different points of view.
 OLAP allows users to analyze database
information from multiple database
systems at one time.
 OLAP data is stored in multidimensional
databases.

 Some popular OLAP server software
programs include:
 Oracle Express Server
 Hyperion Solutions Essbase

 OLAP processing is often used for data
mining.

 OLAP products are typically designed for
multiple-user environments, with the cost of
the software based on the number of users.

THE OLAP CUBE
 An OLAP Cube is a data structure that allows
fast analysis of data.

 The arrangement of data into cubes overcomes a
limitation of relational databases.

 It consists of numeric facts called measures which
are categorized by dimensions.

 The OLAP cube consists of numeric facts called
measures which are categorized by dimensions.

 A multidimensional cube can combine
data from disparate data sources and
store the information in a fashion that is
logical for business users.

HISTORY OF OLAP
 The term OLAP was created as a slight modification
of the traditional database term OLTP (Online
Transaction Processing).

 Databases configured for OLAP employ a
multidimensional data model, allowing for complex
analytical and ad-hoc queries with a rapid execution
time.

 They borrow aspects of navigational databases and
hierarchical databases that are speedier than their
relational kind.

/Contd…
 Nigel Pendse has suggested that an alternative
and perhaps more descriptive term to describe
the concept of OLAP is Fast Analysis of
Shared Multidimensional Information
(FASMI).

 The first product that performed OLAP queries
was Express, which was released in 1970 (and
acquired by Oracle in 1995 from Information
Resources). However, the term did not appear
until 1993 when it was coined by Ted Codd,
who has been described as "the father of the
relational database".

OLAP OPERATIONS
 The user-initiated process of navigating by calling
for page displays interactively, through the
specification of slices via rotations and drill
down/up is sometimes called "slice and dice".

 Slice: A slice is a subset of a multi-dimensional
array corresponding to a single value for one or
more members of the dimensions not in the
subset.

 Dice: The dice operation is a slice on more than
two dimensions of a data cube (or more than two
consecutive slices).

 Drill Down/Up: Drilling down or up is a specific
analytical technique whereby the user navigates among
levels of data ranging from the most summarized (up) to
the most detailed (down).

 Roll-up: A roll-up involves computing all of the data
relationships for one or more dimensions. To do this, a
computational relationship or formula might be defined.

 Pivot: To change the dimensional orientation of a report
or page display.

 The output of an OLAP query is typically displayed in a
matrix (or pivot) format. The dimensions form the row
and column of the matrix; the measures, the values.

DATA WAREHOUSE
 A data warehouse is a repository of an organization's
electronically stored data.
 A data warehouse is a
o subject-oriented,
o integrated,
o time-varying,
o non-volatile
collection of data that is used primarily in organizational
decision making.
 The essential components of a data warehousing system are
the means to:
 Retrieve & Analyze data
 Extract, Transform & Load data
 Manage the data dictionary.

 Data warehouse is a collection
of data designed to support management
decision making.

 Data warehouses contain a wide variety of
data that present a coherent picture of
business conditions at a single point in time.

 The term data warehousing generally refers
to the combination of many different
databases across an entire enterprise.

BENEFITS
 A data warehouse provides a common data
model for all data of interest regardless of the
data's source.

 Priorto loading data into the data warehouse,
inconsistencies are identified and resolved. This
greatly simplifies reporting and analysis.

 Information in the data warehouse is under the
control of data warehouse users so that, even if
the source system data is cleared over time, the
information in the warehouse can be stored
safely for extended periods of time.

 Because they are separate from operational
systems, data warehouses provide retrieval
of data without slowing down operational
systems.

 Datawarehouses facilitate decision support
system applications such as trend reports,
exception reports, and reports that show
actual performance versus goals.

 Data warehouses can work in conjunction
with and, hence, enhance the value of
operational business applications, notably
customer relationship management (CRM)
systems.

DATA WAREHOUSE ARCHITECHTURE
 Architechture is a conceptualization of how the data
warehouse is built.

 One possible simple conceptualization of a data
warehouse architecture consists of the following
interconnected layers:

 Operational database layer: The source data for the
data warehouse - An organization's ERP systems fall
into this layer.

 Informational access layer: The data accessed for
reporting and analyzing and the tools for reporting and
analyzing data - Business intelligence tools fall into this
layer. And the Inmon-Kimball differences about design
methodology, discussed later in this article, have to do

 Dataaccess layer: The interface between the
operational and informational access layer -
Tools to extract, transform, load data into the
warehouse fall into this layer.

 Metadata layer: The data directory - This is
often usually more detailed than an operational
system data directory. There are dictionaries for
the entire warehouse and sometimes
dictionaries for the data that can be accessed by
a particular reporting and analysis tool.

DATA WAREHOUSING
ARCHITECHURE
Monitoring & Administration
OLAP servers

Metadata
Repository
Analysis
DATA
Extract
Query/
External WAREHOUSE
Transform Serv Reporting
Sources
Load e
Operational Refresh Data
databases Mining

APPLICATIONS OF
DATA WAREHOUSES

Data Mining
Web Mining
Decision Support Systems (DSS)

TWO TYPES OF
DATABASE ACTIVITY

 OLTP (Online-Transaction
Processing)

 OLAP (Online-Analytical
Processing)

AT A GLANCE…
 OLTP: On-Line  OLAP: On-Line
Transaction Processing Analytical Processing
 Short Transaction both  Long transactions,
query and updates usually Complex
 (e.g., update account queries.
balance, enroll is
 (e.g., all statistics about
courses)
sales, grouped by
 Queries are Simple department and month)
 (e.g., find account  “Data mining”
balance, find grade in
operations.
courses)
 Infrequent Updates.
 Updates are frequent
 (e.g., Concert tickets,
seat reservations,
shopping carts)

DIFFERENCE BETWEEN
OLTP & OLAP
Item OLTP OLAP

User IT Professional Knowledge worker

Functional Daily task Decision Making

DB Design Application oriented Subject oriented

Historical,
Up to date, detail,
Data multidimensional,
relational
integrated

Access Read/write Read only

DB Size 100 MB-GB 100 GB-TB

TYPES OF OLAP
 Relational OLAP(ROLAP):
Extended RDBMS with multidimensional data
mapping to standard relational operation.

 Multidimensional OLAP(MOLAP): Implemented
operation in multidimensional data.

 Hybrid OnlineAnalytical Processing (HOLAP)
is a hybrid approach to the solution where the
aggregated totals are stored in a
multidimensional database while thedetail data
is stored in the relational database. This is the
balance between the data efficiency of the
ROLAP model and the performance of the
MOLAP model.

Relational OLAP
 Provides functionality by using relational
databases and relational query tools to
store and analyze multidimensional data.
 Build on existing relational technologies
and represent extension to all those
companies who already used RDBMS.
 Multidimensional data schema support
within the RDBMS.
 Data access language and query
performance are optimized for
multidimensional data.
 Support for very large databases.

Multidimensional OLAP
 MOLAP extends OLAP functionality to
MDBMS.
 Best suited to manage, store and analyze
multidimensional data.
 Proprietary techniques used in MDBMS.
 MDBMS and users visualize the stored
data as a 3-Dimensional Cube i.e Data
Cube.
 MOLAP Databases are known to be much
faster than the ROLAP counter parts.
 Data cubes are held in memory called
“Cube Cache”

ROLAP v/s MOLAP
Characteristics ROLAP MOLAP

SCHEMA User star Schema User Data cubes
•Additional •Addition dimensions
dimensions can be require recreation of
added dynamically. data cube.
Database Size Medium to large Small to medium

Architecture Client/Server Client/Server

Access Support ad-hoc Limited to pre-defined
requests dimensions

Characteristics ROLAP MOLAP

Resources HIGH VERY HIGH

Flexibility HIGH LOW

Scalability HIGH LOW

Speed •Good with small data •Faster for small to
sets. medium data sets.
•Average for medium •Average for large
to large data set. data sets.

Implementation of OLAP
server
 ROLAP:
 Data is stored in tables in relational
database or extended relational databases.
 They use an RDBMS to manage the
warehouse data and aggregations using
often a star schema.
 Advantage:
 Scalable
 Disadvantage:
 Direct access to cells.

 MOLAP:
 Implements the multidimensional view
by storing data in special
multidimensional data structures.
 Advantages:
 Fast indexing to pre-computed
aggregations.
 Only values are stored.
 Disadvantage:
 Not very Scalable

APPLICATIONS OF OLAP
OLE DB for OLAP
OLE DB for OLAP (abbreviated ODBO) is
a Microsoft published specification and an industry
standard for multi-dimensional data processing.
ODBO is the standard application
programming interface (API) for exchanging
metadata and data between an OLAP server and a
client on a Windows platform.
ODBO was specifically designed for Online
Analytical Processing (OLAP) systems by
Microsoft as an extension to Object Linking and
Embedding Database (OLE DB).

/Contd…
Marketing and sales analysis

Consumer goods industries

Financial services industry
(insurance, banks etc)

Database Marketing

BENEFITS OF OLAP
 One main benefit of OLAP is consistency of
information and calculations.

 "What if" scenarios are some of the most popular uses
of OLAP software and are made eminently more possible
by multidimensional processing.

 It allows a manager to pull down data from an OLAP
database in broad or specific terms.

 OLAP creates a single platform for all the information
and business needs, planning, budgeting,
forecasting, reporting and analysis.

References
 1.http://en.wikipedia.org/wiki/Online_analytical_proces
sing

 2. http://www.dmreview.com/issues/19971101/964-
l.html

 3. http://en.wikipedia.org/wiki/Extract,_transform,_load

 4. http://www.olapreport.com/Applications.html

OLAP & DATA WAREHOUSE

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