Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Define the Query optimisation
The query parser commonly generates a standard initial tree to correspond to an SQL query, with no doing any optimization. Such type of a canonical query tree denotes a relational algebra expression that is extremely inefficient if executed directly. A query commonly has many possible execution strategies, and the process of choosing a appropriate one for processing a query is termed as query optimization. The major guidelines that are applied throughout query optimization are:
a. Combine a cascade of selections
b. Combine a cascade of projections
c. Commute selection and projection
d. Commuting selection with join / cartesian product Commuting projection with join or cartesian product
e. Commute projection with set operations
f. Commute selection with set operations
How many types of users works on database? Users are differentiated through the way they expect to interact along with the system (i) Application programmers-interact with
atient(PNumber, Name, NHS_no, Amount_due, DNO, Doctor, Medical_Treatment), relation of schema Staff(StaffNum, Name, DNO, Task) and relation of schema Dept(DNO, Name, Location, Dire
Define According to the levels of abstraction, the schema at the intermediate level is called Ans: As per to the levels of abstraction, the schema at the intermediate level is
What is meant by heuristic optimisation? Discuss the main heuristics that are applied during query optimisation. Ans: In heuristic optimization, heuristics are employed to r
pine vally company
Failure Controlling Methods: Failures can be handled using different recovery methods that are talk about later in the unit. But the first question is doing we really require recov
Let us first describe the term relationships. What Are Relationships? A relationship can be defined as: A set of associations or connection, or A rule for communic
1. Create the tables for the play-scheme database as specified in the TMA. 2. Enter the data as given in the spreadsheet. 3. Create queries to retrieve specified information
Modular growth: In distributed environments, it is simple to expand. Latest sites can be added to the network without affecting the operations of other sites, as they are somewhat
Differentiate between a Global and a Local temporary table? - A local temporary table exists only for the duration of a connection or if defined inside a compound statement, fo
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd