Pentaho Aggregation Designer Overview

The Pentaho Aggregation Designer simplifies the creation and deployment of aggregate tables that improve the performance of your Pentaho Analysis (Mondrian) OLAP cubes. Pentaho Analysis is a pure, relational OLAP engine that works solely with the data stored in your relational database rather than providing its own multidimensional data storage model. This simplifies deployment and data management, but places limitations on performance when working with very large data sets (fact tables with more than 10 million records and/or cubes with a high cardinality of levels and members). To improve performance in these scenarios, Pentaho Analysis supports aggregate tables. Aggregate tables coexist with the base fact table and contain pre-aggregated measures built from the fact table. This improves performance by enabling the Mondrian engine to fulfill certain summary level queries from the smaller aggregate table versus aggregating a large number of individual facts from the base fact table.

The Pentaho Aggregation Designer provides you with a simple interface that allows you to create
aggregate tables from levels within the dimensions you specify. Based on these selections, the
Aggregation Designer generates the Data Definition Language (DDL) for creating the aggregate
tables, the Data Manipulation Language (DML) for populating them, and an updated Mondrian
schema which references the new aggregate tables. If you are unfamiliar with aggregate table
design concepts, the Aggregation Designer also includes an intelligent adviser that evaluates the
structure and cardinality of your OLAP cube and recommends some initial aggregate tables to
create for improving performance.

PAD - Installation Instructions

The pad-open-1.0-xx.zip file contains all the libraries and script files necessary to run Pentaho
Aggregation Designer. To install the Pentaho Aggregation Designer, unzip this file into a directory of your choice.

To launch the Aggregation Designer on Windows...

Run the startaggregationdesigner.bat script located in the root of your installation directory.

To launch the Aggregation Designer on Linux...
Run the startaggregationdesigner.sh script located in the root of your installation directory.

CAUTION: Place your JDBC driver JARs in the Drivers directory. Once in this directory, the drivers are added to the classpath automatically when the Pentaho Aggregation Designer starts.

Source: Pentaho

If you want to learn more about it, please visit the link below:
http://blog.professorcoruja.com/2010/11/melhore-performance-de-seus-cubos-olap.html