Categorization of OLAP

OLAP can be categorized into different types based on its architecture and the way it processes data. Here are some of the different types of OLAP and their examples and query techniques:

•     ROLAP (Relational OLAP): This type of OLAP works directly with relational databases and SQL queries. The data is stored in a relational database, and queries are executed against the database to generate reports. ROLAP is useful for handling large volumes of data and complex queries.

•     Example: Microsoft SQL Server Analysis Services

•     Query Technique: SQL queries

•     MOLAP (Multidimensional OLAP): This type of OLAP stores data in a multidimensional cube structure, which allows for faster processing of data and complex calculations. MOLAP cubes can be pre-aggregated, which improves query performance.

•     Example: IBM Cognos TM1

•     Query Technique: MDX (multidimensional expressions)

•     HOLAP (Hybrid OLAP): This type of OLAP combines the features of both ROLAP and MOLAP. It stores the data in a relational database and uses a multidimensional cube structure for querying.

•     Example: Oracle Essbase

•     Query Technique: SQL and MDX

•     DOLAP (Desktop OLAP): This type of OLAP is designed for small-scale data analysis and runs on a desktop computer. It can be used to perform ad-hoc queries and analysis.

•     Example: Microsoft Excel

•     Query Technique: Point-and-click interface or formula-based calculations.

•     WOLAP (Web-based OLAP): This type of OLAP runs on a web browser and allows users to access data remotely. It is useful for collaborative data analysis and reporting.

•     Example: MicroStrategy Web

•     Query Technique: Point-and-click interface or SQL-like queries.