CoderFunda
  • Home
  • About us
    • Contact Us
    • Disclaimer
    • Privacy Policy
    • About us
  • Home
  • Php
  • HTML
  • CSS
  • JavaScript
    • JavaScript
    • Jquery
    • JqueryUI
    • Stock
  • SQL
  • Vue.Js
  • Python
  • Wordpress
  • C++
    • C++
    • C
  • Laravel
    • Laravel
      • Overview
      • Namespaces
      • Middleware
      • Routing
      • Configuration
      • Application Structure
      • Installation
    • Overview
  • DBMS
    • DBMS
      • PL/SQL
      • SQLite
      • MongoDB
      • Cassandra
      • MySQL
      • Oracle
      • CouchDB
      • Neo4j
      • DB2
      • Quiz
    • Overview
  • Entertainment
    • TV Series Update
    • Movie Review
    • Movie Review
  • More
    • Vue. Js
    • Php Question
    • Php Interview Question
    • Laravel Interview Question
    • SQL Interview Question
    • IAS Interview Question
    • PCS Interview Question
    • Technology
    • Other

08 April, 2022

Log-Based Recovery

 Programing Coderfunda     April 08, 2022     RDBMS     No comments   

 

Log-Based Recovery

  • The log is a sequence of records. The log of each transaction is maintained in some stable storage so that if any failure occurs, then it can be recovered from there.
  • If any operation is performed on the database, then it will be recorded in the log.
  • But the process of storing the logs should be done before the actual transaction is applied in the database.

Let's assume there is a transaction to modify the City of a student. The following logs are written for this transaction.

  • When the transaction is initiated, then it writes the 'start' log.
    1. <Tn, Start>  
  • When the transaction modifies the City from 'Noida' to 'Bangalore', then another log is written to the file.
    1. <Tn, City, 'Noida', 'Bangalore' >  
  • When the transaction is finished, then it writes another log to indicate the end of the transaction.
    1. <Tn, Commit>  

There are two approaches to modifying the database:

1. Deferred database modification:

  • The deferred modification technique occurs if the transaction does not modify the database until it has committed been.
  • In this method, all the logs are created and stored in the stable storage, and the database is updated when a transaction commits.

2. Immediate database modification:

  • The Immediate modification technique occurs if database modification occurs while the transaction is still active.
  • In this technique, the database is modified immediately after every operation. It follows an actual database modification.

Recovery using Log records

When the system is crashed, then the system consults the log to find which transactions need to be undone and which need to be redone.

  1. If the log contains the record <Ti, Start> and <Ti, Commit> or <Ti, Commit>, then the Transaction Ti needs to be redone.
  2. Iflogthe contains record<Tn, Start> but does not contain the record either <Ti, commit> or <Ti, abort>, then the Transaction Ti needs to be undone.
  • Share This:  
  •  Facebook
  •  Twitter
  •  Google+
  •  Stumble
  •  Digg
Email ThisBlogThis!Share to XShare to Facebook
Newer Post Older Post Home

0 comments:

Post a Comment

Thanks

Meta

Popular Posts

  • Sitaare Zameen Par Full Movie Review
     Here’s a  complete Vue.js tutorial for beginners to master level , structured in a progressive and simple way. It covers all essential topi...
  • AI foot tracking model
    I am a student doing a graduation project. I urgently need to deal with this model (I am attaching a link). I've never worked with pytho...
  • Laravel Search String
      Laravel Search String is a package by   Loris Leiva   that generates database queries based on one unique string using a simple and custom...
  • Writing and debugging Eloquent queries with Tinkerwell
    In this article, let's look into the options that you can use with Tinkerwell to write and debug Eloquent queries easier. The post Wr...
  • The token request was rejected by the remote server
    error:invalid_granterror_description:The token request was rejected by the remote server.error_uri: https://documentation.openiddict.com/err...

Categories

  • Ajax (26)
  • Bootstrap (30)
  • DBMS (42)
  • HTML (12)
  • HTML5 (45)
  • JavaScript (10)
  • Jquery (34)
  • Jquery UI (2)
  • JqueryUI (32)
  • Laravel (1017)
  • Laravel Tutorials (23)
  • Laravel-Question (6)
  • Magento (9)
  • Magento 2 (95)
  • MariaDB (1)
  • MySql Tutorial (2)
  • PHP-Interview-Questions (3)
  • Php Question (13)
  • Python (36)
  • RDBMS (13)
  • SQL Tutorial (79)
  • Vue.js Tutorial (69)
  • Wordpress (150)
  • Wordpress Theme (3)
  • codeigniter (108)
  • oops (4)
  • php (853)

Social Media Links

  • Follow on Twitter
  • Like on Facebook
  • Subscribe on Youtube
  • Follow on Instagram

Pages

  • Home
  • Contact Us
  • Privacy Policy
  • About us

Blog Archive

  • July (4)
  • September (100)
  • August (50)
  • July (56)
  • June (46)
  • May (59)
  • April (50)
  • March (60)
  • February (42)
  • January (53)
  • December (58)
  • November (61)
  • October (39)
  • September (36)
  • August (36)
  • July (34)
  • June (34)
  • May (36)
  • April (29)
  • March (82)
  • February (1)
  • January (8)
  • December (14)
  • November (41)
  • October (13)
  • September (5)
  • August (48)
  • July (9)
  • June (6)
  • May (119)
  • April (259)
  • March (122)
  • February (368)
  • January (33)
  • October (2)
  • July (11)
  • June (29)
  • May (25)
  • April (168)
  • March (93)
  • February (60)
  • January (28)
  • December (195)
  • November (24)
  • October (40)
  • September (55)
  • August (6)
  • July (48)
  • May (2)
  • January (2)
  • July (6)
  • June (6)
  • February (17)
  • January (69)
  • December (122)
  • November (56)
  • October (92)
  • September (76)
  • August (6)

Loading...

Laravel News

Loading...

Copyright © CoderFunda | Powered by Blogger
Design by Coderfunda | Blogger Theme by Coderfunda | Distributed By Coderfunda