What is system log, Database Management System

Assignment Help:

What is system log?  What are the entries?      

Ans:  The system log that is generally written on stable storage contains the redundant data required to recover from volatile storage failures and as well from errors discovered by the transaction or the database system. System log is as well known as log and has sometimes been called the DBMS journal. It consists of the following entries (also known as log records):

a. [start_transaction, T]: Points out that transaction T has started execution.

b. [write_item, T, X, old_value, new_value]: Points out that transaction T has changed the value of database item X from old_value to new_value.

c. [read_item, T, X]: Points out that transaction T has read the value of database item X.

d. [commit, T]: Points out that transaction T has completed successfully, and affirms that its effect can be committed (recorded permanently) to the database.

e. [abort, T]: Points out that transaction T has been aborted.


Related Discussions:- What is system log

What is null described testing for null in sql?, What is NULL? Give an exa...

What is NULL? Give an example to described testing for NULL in SQL? The NULL SQL keyword is used to represent either a missing value or a value which is not applicable in a re

Remove all transitive dependencies - dependency diagram, 1. Use the Invoice...

1. Use the Invoice table structure shown below to answer the following questions: a)  Draw the dependency diagram and identify the primary key and all dependencies, including al

Normalization assigment, what would go in order patient#, patient name, pat...

what would go in order patient#, patient name, patien address, surgeon#, surgeon name, surgery date, surgery type, drug admin

What is a sub-query, (a) What is a Sub-Query? (b) What is the differen...

(a) What is a Sub-Query? (b) What is the difference between a scalar sub-query and a tabular sub-query? (c) Write an equivalent SQL statement to get the Name of Product wh

Physical records, Physical Records These are the records that are store...

Physical Records These are the records that are stored in the secondary storage devices. For the database relation, physical records are the group of fields kept in adjacent me

Project on designing and creating a database , This project will involve de...

This project will involve designing and creating a database for an organization.  In the design of a database, there is no single "perfect" design.  So your database design may not

What is olap, What is OLAP? OnLine Analytical Processing (OLAP) is a Bu...

What is OLAP? OnLine Analytical Processing (OLAP) is a Business Intelligence (BI) reporting system. OLAP gives the user with the capability to sum, count, average and do other

Develop a web site to present decision tree structure, I am going to develo...

I am going to develop a web site to present decision tree structure. For this, I want a web application with AJAX technology to connect the database and prepare the decision tree's

Need ssd information database completion for wp website, We are looking to ...

We are looking to find someone to prepare a database which improves upon the one we are using at present. The present database will be found here: Click on filter options and yo

Explain cascade and restrict clauses of drop schema command, Explain severa...

Explain several types of constraints that can be specified using CREATE TABLE command. Explain CASCADE and RESTRICT clauses of DROP SCHEMA command? Constraint Description PRIM

Write Your Message!

Captcha
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!

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