'Lossless join' presentation slideshows

Lossless Decomposition& 4NF

CS157B Lecture 16. Lossless Decomposition& 4NF. Prof. Sin-Min Lee Department of Computer Science. 1. Closure. Given a set of functional dependencies, F, its closure, F + , is all FDs that are implied by FDs in F. e.g. If A ? B, and B ? C, then clearly A ? C.

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Normalization

Normalization. ???????????????. The Evils of Redundancy. Redundancy is at the root of several problems associated with relational schemas: redundant storage, insert/delete/update anomalies( ??????? )

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Normalization

Normalization. Lossless Decomposition. Theorem A decomposition of R into R 1 and R 2 is lossless join wrt FDs F, if and only if at least one of the following dependencies is in F + : R 1 ? R 2 ? R 1 R 1 ? R 2 ? R 2

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Loss-Less Joins

Loss-Less Joins. Decompositions. Dependency-preservation property : enforce constraints on original relation by enforcing some constraints on resulting relations Lossless-join property : get original relation by joining the resulting relations Boyce-Codd normal form (BCNF): lossless join

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Schema Refinement and Normal Forms

Schema Refinement and Normal Forms. The Evils of Redundancy. Redundancy is at the root of several problems associated with relational schemas: redundant storage, insert/delete/update anomalies

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Schema Refinement and Normal Forms

Schema Refinement and Normal Forms. Instructor: Xintao Wu. The Evils of Redundancy. Redundancy is at the root of several problems associated with relational schemas: redundant storage, insert/delete/update anomalies

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Functional Dependencies and Normalization

Functional Dependencies and Normalization. R&G Chapter 19 Lecture 26. Science is the knowledge of consequences, and dependence of one fact upon another. Thomas Hobbes (1588-1679 ). Administrivia. Homework 5 available Due a week from next Tuesday Final exam 4 weeks from yesterday.

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CS 222 Database Management System Spring 2010-11 Lecture 5 Database Design (Decomposition)

CS 222 Database Management System Spring 2010-11 Lecture 5 Database Design (Decomposition). Korra Sathya Babu Department of Computer Science NIT Rourkela. Recap. Design of DB is needed to reduce redundancy and anomalies The theory of Functional Dependency is completely studied

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Non Trivial FD

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Normal Forms and XML

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Schema Refinement and Normalization

Schema Refinement and Normalization. Functional Dependencies (Review). A functional dependency X ? Y holds over relation schema R if, for every allowable instance r of R: t1 ? r, t2 ? r, p X ( t1 ) = p X ( t2 ) implies p Y ( t1 ) = p Y ( t2 )

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Normalization

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ICS 421 Spring 2010 Normal Forms

ICS 421 Spring 2010 Normal Forms. Asst. Prof. Lipyeow Lim Information & Computer Science Department University of Hawaii at Manoa. Two More Rules. Union If X ? Y and X ? Z , then X ? YZ Eg . FLD ? A and FLD ? T, then FLD ? AT Decomposition If X ? YZ , then X ? Y and X ? Z

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Outline: Lossless -join (15.1.3) Basic definition of Lossless -join Examples Testing algorithm

Outline: Lossless -join (15.1.3) Basic definition of Lossless -join Examples Testing algorithm. Basic definition of Lossless -join A decomposition D = {R 1 , R 2 ,..., R m } of R has the lossless

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ICS 321 Fall 2011 Normal Forms (ii)

ICS 321 Fall 2011 Normal Forms (ii). Asst. Prof. Lipyeow Lim Information & Computer Science Department University of Hawaii at Manoa. Redundancies & Decompositions. Hourly_Emps. Hourly_Emps. RatingWages. Decompositions.

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Normalization

Normalization. Normal Forms. If a relation is in a certain normal form ( BCNF, 3NF etc.), it is known that certain kinds of redundancies are avoided/minimized. This can be used to help us decide whether decomposing the relation will help. Role of FDs in detecting redundancy:

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Normalization

Normalization. Normal Forms. If a relation is in a certain normal form ( BCNF, 3NF etc.), it is known that certain kinds of redundancies are avoided/minimized. This can be used to help us decide whether decomposing the relation will help. Role of FDs in detecting redundancy:

293 views • 11 slides

Decompositions

Decompositions. Given a relation schema R that is not in 3NF (or perhaps BCNF) decomposition can be used to help fix this problem Decomposition replaces R with R1,...,RN where 1) attributes of Ri are a subset of the attributes of R 2) each attribute of R is in at least one Ri

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