Session17

Session17 - CSCI585 CSCI585 C. Shahabi Multidimensional...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CSCI585 CSCI585 C. Shahabi Multidimensional Databases Cyrus Shahabi Computer Science Department University of Southern California shahabi@usc.edu CSCI585 CSCI585 C. Shahabi Outline s Definitions (from A.R. 20 and 21) s Focus Application: OLAP s Prefix-Sum (from A.R. 16) s Dynamic Data Cube (from A.R. 17) s Iterative Data Cube (from A.R. 18) s Wavelet-based approaches r Compact Data Cube (from A.R. 19) r ProPolyne (from A.R. 22 and 23) CSCI585 CSCI585 C. Shahabi Definitions s During the past decade, the multidimensional data model emerged for use when the objective is to analyze data rather than to perform online transactions. s In contrast to previous technologies, these databases view data as multidimensional cubes that are particularly well suited for data analysis. s Multidimensional data models have three important application areas within data analysis: r Data warehouses are large repositories that integrate data from several sources in an enterprise for analysis. r Online analytical processing (OLAP) systems provide fast answers for queries that aggregate large amounts of detail data to find overall trends. r Data mining applications seek to discover knowledge by searching semi-automatically for previously unknown patterns and relationships in multidimensional databases. CSCI585 CSCI585 C. Shahabi Definitions s Multidimensional databases view data as cubes that generalize spreadsheets to any number of dimensions. s In addition, cubes support hierarchies in dimensions and formulas without duplicating their definitions. s A collection of related cubes comprises a multidimensional database or data warehouse. s Dimensions are used for selecting and aggregating data at the desired level of detail. s A dimension is organized into a containment-like hierarchy composed of numerous levels, each representing a level of detail required by the desired analyses. s Each instance of the dimension, or dimension value, belongs to a particular level. CSCI585 CSCI585 C. Shahabi Definitions s Facts represent the subjectthe interesting pattern or event in the enterprise that must be analyzed s In most multidimensional data models, facts are implicitly defined by their combination of dimension values; a fact exists only if there is a nonempty cell for a particular combination of values. s A measure consists of two components: r a facts numerical property, such as the sales price or profit r a formul a, usually a simple aggregation function such as sum , that can combine several measure values into one. s In a multidimensional database, measures generally represent the properties of the fact that the user wants to optimize. Measures then take on different values for various dimension combinations....
View Full Document

Page1 / 43

Session17 - CSCI585 CSCI585 C. Shahabi Multidimensional...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online