Overview
This chapter covers the types of OLAP operations, OLAP system, and its application.This OLAP tutorial is designed to introduce the fundamentals of OLAP.
All big corporate company used relational database system.A relational database structure that is ideal for a transaction based system are all big corporate company used relational database system.
A relational database structure that is ideal for transaction based system is often too complex for non-IT expert (Business expert) to understand or summarize vast volume of old and new data.
Example-When sales company needs to generate a report of sales for the specific month with some of their product than it slows down the system to generate the report when the volume of data is too vast so due to this issue performance of business degrade in some extent.
A solution of above problem is OLAP(online analytical processing).OLAP is a snapshot of data at the specific point of time. OLAP system provides slicing, dicing, pivoting dimension, drill down, drill up through the hierarchy.
This OLAP tutorial help to learn OLAP in a simple and easy manner using this.This OLAP tutorial provides different OLAP operations such as slicing, dicing, drill down and drill across.
Terminology
Some of the terminologies which are generally used in OLAP , explain in this OLAP tutorial
Cube – Cube refers to a multi-dimension data set, A cube has dimension and measures.Sometimes a cube is called a hypercube if the number of dimensions is greater than 3.
Dimension – Dimension will have a number of members and each member will have a collection of attributes, some of them organized into hierarchies. Dimensions are either defined at the Schema level, or as part of a Cube within a Dimensions element.
Measures – Measures are the quantities you want to measure.we perform a different mathematical operation on it.Measures are always a numeric value.
Hierarchy – A logical tree structure that organizes the members of a dimension such that each member has one parent member and zero or more child members. A child is a member in the next lower level in a hierarchy that is directly related to the current member.
Level – Within a hierarchy, data can be organized into lower and higher levels of details, such as Year, Quarter, Month, and Day levels in a Time hierarchy.
OLAP AnalysisOLAP (online analytical processing)systems help to analyze the stored data.OLAP applications are widely used by Data Mining techniques.OLAP provides multi-dimensional analysis of data and also stored data in multidimensional form schema.
OLAP Operations
Slice
Slicing is nothing but a piece of the cube.
Performs a selection on one dimension of the given cube and provide a sub-cube.
Reduces the dimensionality of the cubes.
Example-In cooking, you can slice a vegetable or other food in small pieces.
Dice
Dice selects two or more dimensions from a given cube and provides a new sub-cube.
Select condition on more than one dimension.Reduces the number of member values of one or more dimensions.
Drilling down or roll up is a specific analytical technique whereby the user navigates among hierarchy levels of data ranging from the most summarized (up)to the most detailed (down).
Drill Up(Roll up)
Decrease data granularity.
Perform aggregation on a data cube by – Climbing up a concept hierarchy for a dimension
Dimension reduction
Summarize data
Going up a level in the hierarchy is called drilling up the data.
Drill Down(Roll down)
Increase data granularity.
Navigates from less detailed data to more detailed data by – Stepping down a concept hierarchy for a dimension
Introducing additional dimensions
Going down a level in the hierarchy is called drilling down the data.
Pivot
Rotates the data axes in order to view the data from different perspectives.
All these terms are used to mean the presentation of information in a variety of different and useful ways.
Other OLAP operations some more OLAP operations include
DRILL ACROSS: Execute query involving more than one fact table.
DRILL THROUGH: Drill down to the bottom level of a data cube down to its back end relational tables.
Types of OLAP Systems
1.Relational OLAP (ROLAP).
2.Multidimensional OLAP (MOLAP).
3.Hybrid OLAP (HOLAP).
To know more about the type of OLAP System click here (http://olap.com/types-of-olap-systems/).
OLAP Application
OLAP is widely used in various data management.Some of their application follows: –
- Financial Applications.
- Marketing/Sales Applications Business.
- Business modeling management.
- Reporting.
- Business Performance management.
To learn more about the power of OLAP with Saiku click here.
