Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Chapter 7, Problem 43E
Program Plan Intro
Materialized view:
- Materialized view is a
database object that contains the result of a query. - It is mainly used for increasing application performance.
- It is used for replicating data and to cache expensive queries in a data warehouse environment.
</PROGRAM-PLAN-INNTRO>
Constraints on materialized views enforcing functional dependency:
- The constraints on materialized view helps for increasing execution speed.
- Materialized view is refreshed by the type of materialized view.
- The constraints under materialized view should be normalized.
- That means each dimension should be contained in one table.
- Also, the joins between tables must be normalized or partially normalized.
- Hence, there is a guarantee that each child side row joins with exactly one parent side row.
- Hence, constraints on materialized view can be used for enforcing functional dependency.
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So SQL does not suppor functional depency constraints. However, if the database system supports constraints on materialized views and materialized views are maintained immediately, is it possible to enforce the functional dependency constraints in SQL?
If it is possible, for a relation r(A,B,C), how can the constraints on materialized views be used to enforce a functional dependency, like B->A?
Consider a database containing two relations: R(A,B,C) and S(D,E,F). For each of three (your choice) of the 12 rewriting rules for relational algebra expression, give an example pair of relational algebra expressions involving R and S such that the rule rewrites one expression to the other expression, and give another example pair to show the rewriting rule cannot be used since some of the conditions for the rule arenot satisfied
Q7. Consider a database containing two relations: R(A,B,C) and S(D,E,F). For each of three (your choice) of the 12 rewriting rules for relational algebra expression, give an example pair of relational algebra expressions involving R and S such that the rule rewrites one expression to the other expression, and give another example pair to show the rewriting rule cannot be used since some of the conditions for the rule are not satisfied.
Chapter 7 Solutions
Database System Concepts
Ch. 7 - Prob. 1PECh. 7 - Prob. 2PECh. 7 - Explain how functional dependencies can be used to...Ch. 7 - Prob. 4PECh. 7 - Prob. 5PECh. 7 - Prob. 6PECh. 7 - Prob. 7PECh. 7 - Prob. 8PECh. 7 - Prob. 9PECh. 7 - Prob. 10PE
Ch. 7 - Prob. 11PECh. 7 - Prob. 12PECh. 7 - Prob. 13PECh. 7 - Prob. 14PECh. 7 - Prob. 15PECh. 7 - Prob. 16PECh. 7 - Prob. 17PECh. 7 - Prob. 18PECh. 7 - Prob. 19PECh. 7 - Prob. 20PECh. 7 - Prob. 21ECh. 7 - Prob. 22ECh. 7 -
Explain what is meant by repetition of...Ch. 7 -
Why are certain functional dependencies called...Ch. 7 - Prob. 25ECh. 7 - Prob. 26ECh. 7 - Prob. 27ECh. 7 - Prob. 28ECh. 7 - Prob. 29ECh. 7 - Prob. 30ECh. 7 - Prob. 32ECh. 7 - Prob. 33ECh. 7 - Prob. 35ECh. 7 - Prob. 36ECh. 7 - Prob. 37ECh. 7 - Prob. 38ECh. 7 - Prob. 39ECh. 7 - Prob. 40ECh. 7 - Prob. 41ECh. 7 - Prob. 42ECh. 7 - Prob. 43E
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- Although SQL does not support functional dependency constraints, if thedatabase system supports constraints on materialized views, and materialized views are maintained immediately, it is possible to enforce functional dependency constraints in SQL. Given a relation r(A, B, C), explain how constraints on materialized views can be used to enforce the functional dependency B → C.arrow_forwardTesting SQL queries: To test if a query specified in English has been correctlywritten in SQL, the SQL query is typically executed on multiple test databases,and a human checks if the SQL query result on each test database matches theintention of the specification in English. When creating test databases, it is important to create tuples with null values for foreign-key attributes, provided the attribute is nullable (SQL allows foreign-key attributes to take on null values, as long as they are not part of the primary key and have not been declared as not null). Explain why, using an example query on the university database.arrow_forwardConsider the relation schema R (A, B, C, D) with all possible functional dependencies. For each of the following situations, identify the highest normal form for this relation R. A, C -> B, D C -> D A, C -> B, D B -> D A, C -> B, Darrow_forward
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- Relational Database A relation R is given which is R(A,B,C,D,E). It has the following functional dependencies: BC -> E, E -> A and B -> D. Answer the following based on this information. Find all the candidate keys. What type of dependencies are found in this relation? Which normal form does this relation satisfy? Is it in 3NF? If not, decompose it until 3NFarrow_forwardDATABASE SYSTEM A relation R is given which is R(A,B,C,D,E). It has the following functional dependencies: BC -> ADE , D -> B. Answer the following based on this information. Which normal forms does this relation satisfy? Which type of dependencies does this relation violate? Normalize the relationship so that it decomposes to 3NF.arrow_forwardList all nontrivial functional dependencies satisfied by the relation of Figure7.18.arrow_forward
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