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Published byBedřich Vávra Modified over 5 years ago
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Data Warehouses, Dimensional Modeling, and the Laundromat
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The washers and dryers are like an organization’s operational / transaction systems . . .
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Sorting by color is best for washing, but not for retrieval and wearing!
Reorganize
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ETL is like bringing clothes home and putting them away for easy retrieval!
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Denormalized Star Schema – Common Approach
Fact (core or transaction) Tables in middle of star Dimensional (structural or “lookup”) Tables around “points” of star ORDER TABLE Cust # CustName Moe Larry Curly CUSTOMER DIMENSION Prod # ProdName QR Rake SR Spade TW Mulch PRODUCT DIMENSION Loc # LocName 1000 NY 2000 LA 3000 PGH LOC DIMENSION CUSTOMER TABLE TIME Order # Date Cust# Prod# Loc# Sales Amt /15/XX QR $29.95 /19/XX QR $29.95 /30/XX SR $49.95 Date Quarter 06/29/XX 2 06/30/XX 2 S 07/01/XX 3 Juan SALES ORDER (FACT) TABLE DATE DIMENSION The DW structure reflects Dimensional Modeling
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Common (Conformed) Dimensions
Denormalized Star Schema (continued) Stars are linked via common (i.e., Conformed) Dimensions to form Data Warehouse Cust # CustName Moe Larry Curly Loc # LocName 1000 NY 2000 LA 3000 PGH CUSTOMER DIMENSION LOC DIMENSION Order # Date Cust# Prod# Loc# Sales Amt /15/XX QR $29.95 /19/XX QR $29.95 /30/XX SR $49.95 ORDER TABLE SALES ORDER (FACT) TABLE Common (Conformed) Dimensions Date Quarter 06/29/XX 2 06/30/XX 2 07/01/XX 3 Juan Prod # ProdName QR Rake SR Spade TW Mulch DATE DIMENSION TIME PRODUCT DIMENSION Prod# ProdName Stock Date Units QR22 Rake 03/23/XX TW43 Mulch 04/15/XX 1452 SR56 Spade 05/01/XX INVENTORY (FACT) TABLE
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DW Development Approaches
Inmon Model: EDW approach (top-down) Kimball Model: Data mart approach (bottom-up) Which model is best? Depends
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Bill Inmon (Top-Down) Build an all-encompassing Enterprise Data Warehouse (EDW) When EDW is finished, use it to create subject-oriented Data Marts “Cargo-Ship” approach
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Ralph Kimball (Bottom-Up)
Build subject-oriented Data Marts first Connect the individual Data Marts to create a Data Warehouse Start small and add to Data Warehouse over time “Freight Train” approach
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Best Approach depends on the organization’s resources and needs!
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In-Memory Visualization Tools
Newest End-User Data Analytic Tools Very visual dashboards displays and gauges Stores data in local PC’s RAM (more flexible & faster performance) Can utilize Dimensional Modeling of a Data Warehouse, or model data on local PC Main competitors: Tableau, Qlikview, MS-Power BI
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MS Power BI Demo
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