Datawarehousing y Olap

Data Warehousing and OLAP
Cheung Pui Ling Pauline, Lau Wai Kay Ricky, Lee Tak Wan Angus, Tsoi Chin Ching Lancelot and Yip Keung Frank {cscpl, cpegkay, angus, lance, frank}@ust.hk

Abstract
Data warehousing and on-line analytical processing (OLAP) is becoming an important tool for decision making in corporations and other organizations. It is one of the main focuses of the databaseindustry. However, the functions and properties of decision support system are rather different from the traditional database application. For example, user of decision support system may be interested in the trend of certain data instead of the actual data itself. Another feature of data warehouse system is that the amount of data inside is tremendous, which means that the traditional queryprocess on these data will be very time consuming. In this survey paper, we will mainly discuss several techniques used in data warehouse to accelerate the OLAP process speed. The rest of paper is organized as follows: Chapter 1 is the introduction, in which we will give an overview of current technology used in the area of data warehousing and OLAP. In chapter 2, we will talk about a newaggregation operator which is called Data Cube operator. The Data Cube operator can perform N-dimensional aggregation. From chapter 3, we will begin to discuss one of the most importation is issue in data warehousing and OLAP. That is view materialization and view maintenance. In chapter 3, a general introduction to the problems and techniques of materialized views maintenance will be given.In chapter 4, some techniques developed base on the space constrain of data warehouse will be discussed. In chapter 5, we will use a dynamic view management system to discuss the techniques of dynamic view selection and view maintenance.

1

Abstract.................................................................................................................... 1 Chapter 1.Introduction ................................................................................. 3 Chapter 2. Data Cube Operator ............................................................. 6
2.1 Introduction ......................................................................................................... 6 2.2 Problems with GROUPBY................................................................................. 6 2.3 CUBE and ROLLUP operators ........................................................................... 9 2.4 The Data Cube Operator.................................................................................... 10 2.5 Syntax ................................................................................................................ 10 2.6 MinimalistDesign ............................................................................................. 13 2.7 Addressing the Data Cube ................................................................................. 13 2.8 Computing the Data Cube & Maintaining cubes............................................... 14 2.9 Data CubeSummary.......................................................................................... 14

Chapter 3. Materialized Views and their Maintenance ........ 15
3.1 Introduction ....................................................................................................... 15 3.2 Application of Materialized View ..................................................................... 15 3.3 Materialized ViewMaintenance........................................................................ 16

Chapter 4. Selection of views to materialize in a Data Warehouse
..................................................................................................................................... 19 4.1 Background........................................................................................................ 19 4.2...