'Join trees' diaporamas de présentation

AutoJoin: Providing Freedom from Specifying Joins

AutoJoin: Providing Freedom from Specifying Joins. Terrence Mason ( terrence-mason@uiowa.edu ) Lixin Wang ( lixin-wang@uiowa.edu ) Dr. Ramon Lawrence ( ramon-lawrence@uiowa.edu ) Iowa Database and Emerging Application Laboratory University of Iowa.

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Lecture 25: Query Optimization

Lecture 25: Query Optimization. Wednesday, November 26, 2003. Outline. Cost-based optimization 16.5, 16.6. Cost-based Optimizations. Main idea: apply algebraic laws, until estimated cost is minimal Practically: start from partial plans, introduce operators one by one

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Cost-Based Transformations

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Cost-Based Transformations

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DBXplorer: A System for Keyword-Based Search over Relational Databases.

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Cost-Based Plan Selection Choosing an Order for Joins

Cost-Based Plan Selection Choosing an Order for Joins. Chapter 16.5 and16.6 by:- Vikas Vittal Rao ID: 124/227 Chiu Luk ID: 210. Agenda. Outline Cost Estimation Histograms Computation of statistics Reducing cost of heuristics Enumerating Physical Plans

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Choosing an Order for Joins

Choosing an Order for Joins. Chapter 16.6 by: Chiu Luk ID: 210. Introduction. This section focuses on critical problem in cost-based optimization: Selecting order for natural join of three or more relations

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Cost based transformations

Two candidates for the best logical query plan. Initial logical query plan. Cost based transformations. Cost based transformations. The (estimated) size of ? a =10 ( R ) is 5000/50 = 100 The (estimated) size of ?(? a =10 ( R )) is min{1*100, 100/2} = 50

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Cost based transformations

Two candidates for the best logical query plan. Initial logical query plan. Cost based transformations. Cost based transformations. The (estimated) size of ? a =10 ( R ) is 5000/50 = 100 The (estimated) size of ?(? a =10 ( R )) is min{1*100, 100/2} = 50

163 views • 16 slides

DBXplorer: A System for Keyword-Based Search over Relational Databases Sanjay Agrawal, Surajit Chaudhuri, Gautam Das

DBXplorer: A System for Keyword-Based Search over Relational Databases Sanjay Agrawal, Surajit Chaudhuri, Gautam Das. Cathy Wang 04-04-2006. Outline. Introduction Overview of DBXplorer Publish Search Generalized Matches Conclusion. Introduction.

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Choosing an Order for Joins (16.6)

Choosing an Order for Joins (16.6). Neha Saxena (214) Instructor: T.Y.Lin. Topics Covered. Introduction Significance of Left and Right Join Arguments Join Trees Left-Deep Join Trees Dynamic Programming to Select a Join Order & Grouping Dynamic Programming with More Detailed Cost Functions

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