User Account

All Pages

query optimization, PL-SQL Programming

Assignment Help:
1.( /5 marks) Suppose that a B+-tree index with the search key (dept_name, building) is available on
relation department. What would be the best way to handle the following selection?
?(building = “Watson”) ? (budget < 55000) ? (dept_name = “Music”)(department)
a. 2 marks for clearly showing an equivalent relation algebra expression using the
appropriate, well identified rule supplied in the textbook (e.g., the derivation with rule #
applied).
b. 1.5 marks for clearly explaining how the B+ tree index would be used to evaluate the
conditions involving attributes that are specified as part of the index
c. 1.5 marks for clearly explaining how the remaining conditions that involve attributes that
are not specified as part of the index would be evaluated
2. ( /5 marks) Show how to derive the following relational algebra equivalences by a sequence of
transformations using the relational algebra equivalence rules in Section 13.2.1. Hint: make sure
you clearly define all rules you use; as well identify which rule is being applied and apply only one
rule for each line in your solution – show your work.
a. ??1??2??3 (E) = ??1 (??2 (??3 (E))) (2 marks)
b. ??1??2 (E1 ??3 E2) = ??1 (E1 ??3 (??2 (E2))), where ?2 involves only attributes from E2 (3
marks)
3. ( /5 marks) Consider the two expressions ?? (E1 E2) and ?? (E1 ? E2).
a. Show using a concrete example that the two expressions are not equivalent in general
(3 marks). Hint: first identify what the difference is between natural join and left outer join
(what is extra in the left outer join), and then make sure you give the concrete relation instances
for E1 and E2 that result in a different expression result.
b. Give a simple condition on the predicate ?, which if satisfied will ensure that the two
expressions are equivalent. Hint: Think about what extra tuples you would have in the left

1
Some of the problems are adapted from “Database System Concepts”, 6th Edition, 2011, Avis Silberschatz, Henry
F. Korth, S. Sudarshan.
outer join, how they joined tuple is constructed, and a condition that will exclude these extra
tuples.
4. ( /5 marks) Explain how to use a histogram to estimate the size of a selection of the form ?A=v(r).
Hint: Divide the distribution into n buckets {rj | j ? [1,n]} and consider the two cases: Part 1) the
selection value v is greater than or equal to the largest value of a given bucket ri (2 marks) and Part 2) the
selection value v is “part way” between the max and min values of bucket ri+1. (3 marks).
5. ( /5 marks) Give an example of a relational algebra expression defining a materialized view and
two situations (for the differentials) such that incremental view maintenance is better than
recomputation (recomputing the materialized view from scratch) in one situation (2.5 marks),
and recomputation is better in the other situation (2.5 marks). Hint: think about different values for
x between 0 and 100, where you insert x% tuples are deleted.

Related Discussions:- query optimization

Change sql file into csv for product registration, Change Sql file into CSV...

Change Sql file into CSV for product registration on Magento Project Description: I have a set of files that are in Sql format and could like for a developer to help me with

Declaring cursor variables, Declaring Cursor Variables Once a REF CURS...

Declaring Cursor Variables Once a REF CURSOR type is define by you, and then you can declare the cursor variables of that type in any PL/SQL block or subprogram. In the exampl

Solve the business problems using sql, Use the MASCOT tables CREDITRS, PORD...

Use the MASCOT tables CREDITRS, PORDS and PAYMENTS to write SQL queries to solve the following business problems. These tables / data are available to you via the USQ Oracle server

Effects of null in aggregate operator - sql, Effects of NULL in Aggregate O...

Effects of NULL in Aggregate Operator - SQL Let aggop(x) be an invocation of some aggregate operator aggop in SQL, where x is an expression (usually an open expression) to be

Execute your documentation in oracle, Using research notes and Oracle docum...

Using research notes and Oracle documentation plan and execute an upgrade of an installation of Oracle 10g to Oracle 11g release 1. To do this you must show in screen shots and wri

Organic evolution, Organi c Evolution Evolution is a slow continuou...

Organi c Evolution Evolution is a slow continuous, irreversible and natural process of change to give rise to advance and diverse forms of life i.e. formation of new specie

Operators on tables and rows, Operators on Tables and Rows Row Extrac...

Operators on Tables and Rows Row Extraction TUPLE FROM r, SQL has row subqueries. These are just like scalar subqueries except that they may specify more than one column.

Product-specific packages, Product-specific Packages The Oracle and dif...

Product-specific Packages The Oracle and different Oracle tools are supplied with the product-specific packages which help you to build the PL/SQL-based applications. For illus

Advantages of invoker rights, Advantages of Invoker Rights The Invoker-...

Advantages of Invoker Rights The Invoker-rights routines centralize the data retrieval. They are particularly helpful in applications which store data in various schemas. In su

Scope and visibility- pl/sql, Scope and Visibility The References to an ...

Scope and Visibility The References to an identifier are resolved according to its visibility and scope. The scope of an identifier is that area of a program unit (subprogram, b

Write Your Message!

Captcha
Order Assignment

Featured Services

Order Now

Popular Subjects

Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

Submit Assignment

Academics

Major Subjects

Majors

Get In Touch

whatsapp: +91-977-207-8620

Phone: +91-977-207-8620

Email: [email protected]

TERMS & POLICIES

HELP & SUPPORT

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd