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!
Failures and Recovery
In practice various things might occur to prevent a transaction from completing. Recovery methods are used to bring database, which does not satisfy consistency needs, into a consistent state. If a transaction finishes normally and commits then all the alters made by the transaction on the database are permanently registered in the database. They should not be lost. But, if a transaction does not finish normally and terminates abnormally then all the changes made by it should be discarded. An abnormal termination of a transaction may be because of various causes, including:
a) User may decide to terminate the transaction issued by him/ her
b) There may be a deadlock in the system
c) There may be a system failure.
The recovery mechanisms must make sure that a consistent state of database can be restored under all circumstances. In case of transaction terminate or deadlock, the system remains in control and can deal with the failure but in case of a system failure the system loses control because the computer itself has failed. Will the results of such type of failure be catastrophic? A database has a vast amount of useful information and any system failure should be recognised on the restart of the system. The DBMS should recover from some such failures.
Describe the algorithm for updating indices for a single level index when a record is (i) Inserted (ii) deleted What will be the modification if there are multilevel in
Related fields in a database are grouped in which form? Related data fields in a database are grouped to form a data record. (A record is a collection of related fields)
Hierarchical
Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pictori
Which two files are used during operation of the DBMS? Data dictionary and transaction log are two files used during operation of the DBMS.
Explain the Natural join Natural join is a binary operator which is written as (R* S) in which R and S are relations. The effect of the natural join is the set of all combinati
Create Student DB and execute Insert query? STUDENT (name, student#, class, major) COURSE (course name, course#, credit hours, department) SECTION (section identifier, course
Need for Client Server Computing- Client/Server (C/S) architecture includes running the application on multiple machines in which every machine with its component software tackles
What is a SELECT operation? The select operation selects tuples that please a given predicate. We use the lowercase letter σ to denote selection.
Given the following set of functional dependencies {cf→ bg, g → d, cdg → f, b → de, d → c} defined on R(b,c,d,e,f,g) a. Is cf→ e implied by the FDs? b. Is dg a superkey?
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd