'Left deep join trees' diaporamas de présentation

Cost-Based Transformations

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Cost-Based Transformations

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CS222 P : Principles of Data Management UCI, Fall 2018 Notes # 13 Query Optimization (System-R)

CS222 P : Principles of Data Management UCI, Fall 2018 Notes # 13 Query Optimization (System-R). Instructor: Chen Li. System R Optimizer. Impact: Most widely used currently; works well for < 10 joins. Cost estimation: An approximate art at best ( ?).

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Instructor: Chen Li

CS222 /CS122C : Principles of Data Management UCI, Fall 2018 Notes # 13 Query Optimization (System-R). Instructor: Chen Li. System R Optimizer. Impact: Most widely used currently; works well for < 10 joins. Cost estimation: An approximate art at best ( ?).

232 views • 22 slides

Query Optimization

Query Optimization. Vishy Poosala Bell Labs. Outline. Introduction Necessary Details Cost Estimation Result Size Estimation Standard approach for query optimization Other ways Related Concepts.

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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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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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Relational Query Optimization II: Size Estimation and Plan Generation

Relational Query Optimization II: Size Estimation and Plan Generation. Size Estimation and Reduction Factors. SELECT attribute list FROM relation list WHERE term1 AND ... AND termk. Consider a query block:

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Quiz 2 Review

Quiz 2 Review. For which of the following attributes would a hash-index most likely be a better fit than a B+-tree index? A. Social Security Number B. Age C. Salary D. Last Name E. Starting Date. A given B+-tree index has a height of 4 and maximum fan out of 129 (128 index entries).

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