'Block nested loops join' diaporamas de présentation

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???????? 9. ??????????? ??? ?????????????? ????????? ?? ????????? ?????? ?????????. Query Processing and Optimization. Architecture of the Query Processor in a DBMS Query Processing Implementation of Relational Operators (join, select, project, aggregates, etc.) Use of Indices Buffering

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CMSC424: Database Design

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Overview of Query Evaluation: JOINS

Overview of Query Evaluation: JOINS. Chapter 14. Schema for Examples. Sailors ( sid : integer , sname : string, rating : integer, age : real) Reserves ( sid : integer, bid : integer, day : dates , rname : string). Reserves: Each tuple is 40 bytes long, 100 tuples per page, 1000 pages.

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Evaluation of Relational Operations

Evaluation of Relational Operations. Yanlei Diao UMass Amherst March 01, 2007. Slides Courtesy of R. Ramakrishnan and J. Gehrke. Relational Operations. We will consider how to implement: Selection ( ) Selects a subset of rows from relation.

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File Processing : Query Processing

File Processing : Query Processing. 2008, Spring Pusan National University Ki-Joune Li. Basic Concepts of Query. Query Retrieve records satisfying predicates Types of Query Operators Aggregate Query Sorting. Predicate. Select. Relational Operators : Select.

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Query Processing

Query Processing. Basic Steps in Query Processing. Example. SELECT balance FROM account WHERE balance < 2500 ? balance ?2500 ? balance account. PLAN I. Example. SELECT balance FROM account WHERE balance < 2500

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Evaluation of Relational Operations

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Database Management System

Database Management System. Query Processing. Chapter 13: Query Processing. Overview Measures of Query Cost Selection Operation Join Operation Project Operation Evaluation of Expressions. Basic Steps in Query Processing. 1. Parsing and translation 2. Optimization 3. Evaluation.

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Evaluation of Relational Operations

Evaluation of Relational Operations. Chapter 14, Part B (Joins). Schema for Examples. Sailors ( sid : integer , sname : string, rating : integer, age : real) Reserves ( sid : integer, bid : integer, day : dates , rname : string). Similar to old schema; rname added for variations.

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Evaluation of Relational Operations

Evaluation of Relational Operations. Relational Operations. We will consider how to implement: Selection ( ) Selects a subset of rows from relation. Projection ( ) Deletes unwanted columns from relation. Join ( ) Allows us to combine two relations.

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Evaluation of Relational Operations

Evaluation of Relational Operations. Chapter 14 (3 rd Edition) , Part A (Joins). Relational Operations. We will consider how to implement: Selection ( ) Selects a subset of rows from relation. Projection ( ) Deletes unwanted columns from relation.

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Join Algorithms

Join Algorithms. Chapter 14. Schema for Examples. Sailors ( sid : integer , sname : string, rating : integer, age : real) Reserves ( sid : integer, bid : integer, day : dates , rname : string). Similar to old schema; rname added for variations. Reserves:

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Implementing Relational Algebra: Projection

Implementing Relational Algebra: Projection. To implement projection, we have to: Remove unwanted attributes (attributes not specified in the query). Eliminate any duplicate tuples that are produced. The second step of removing duplicates is very difficult and costly.

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Implementation of Relational Operations: Joins

Implementation of Relational Operations: Joins. Schema for Examples. Sailors ( sid : integer , sname : string, rating : integer, age : real) Reserves ( sid : integer, bid : integer, day : dates , rname : string). Similar to old schema; rname added for variations. Reserves:

126 views • 12 slides