1 / 10

Ch.3 The Multidimensional Data Model

Ch.3 The Multidimensional Data Model. Ch. 3.1 Introduction to MDD Model Requirements: must support typical analyses, queries like Sales of a product group digital cameras in Nov, Dec Jan Feb in Munich area sorted by sales of each product in € sorted by sales in numbers

ilana
Download Presentation

Ch.3 The Multidimensional Data Model

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ch.3 The Multidimensional Data Model Ch. 3.1 Introduction to MDD Model Requirements: must support typical analyses, queries like Sales of aproduct groupdigital cameras in Nov, Dec Jan Feb in Munich area • sorted by sales of each product in € • sorted by sales in numbers • sorted by shops DWH, Ch. 3-1, SS 2001

  2. Operations: • aggregation • slice • dice (würfeln) • rollup to coarser level • drill down to more detailed level • grouping • sorting DWH, Ch. 3-1, SS 2001

  3. Model • need abstract model with above operations • suitable datastructures • very large databases • Relational Model? • one-dimensional access via primary key • n*m „relationships“ are 2-dimensional: (FK1, FK2) DWH, Ch. 3-1, SS 2001

  4. OLAP is inherently multidimensional: • See e.g. above query with dimensions: • procucts • time • geographic region • Additional dimensions might be: • customer group • age group • type of payment { cash, credit, cheque, ...} • outlet { Kaufhof, Quelle, Internet,...} DWH, Ch. 3-1, SS 2001

  5. Relational Representation of Multidimensional Data DWH, Ch. 3-1, SS 2001

  6. Multidimensional Representation of 3-dim Data: Dimensions with Measures or Facts DWH, Ch. 3-1, SS 2001

  7. Representation of 5-dim Data DWH, Ch. 3-1, SS 2001

  8. Logical and Physical Aspects of MD Models • logical view: easy understanding for user, e.g. to formulate queries or to understand result presentation • physical view: storage in computer memory, access methods sparse vs. dense? • Problem: • extremely sparse data at lowest level of granularity, GfK 99.99995 sparsity • dense at higher aggregation levels DWH, Ch. 3-1, SS 2001

  9. Comparison of both Models DWH, Ch. 3-1, SS 2001

  10. FASMI Definition DWH, Ch. 3-1, SS 2002

More Related