Skip to main content

Explain ACID

The ACID model is one of the oldest and most important concepts of database theory. It sets forward four goals that every database management system must strive to achieve: atomicity, consistency, isolation and durability. No database that fails to meet any of these four goals can be considered reliable.

Let’s take a moment to examine each one of these characteristics in detail:


Atomicity :

states that database modifications must follow an “all or nothing” rule. Each transaction is said to be “atomic.” If one part of the transaction fails, the entire transaction fails. It is critical that the database management system maintain the atomic nature of transactions in spite of any DBMS, operating system or hardware failure.


Consistency :

states that only valid data will be written to the database. If, for some reason, a transaction is executed that violates the database’s consistency rules, the entire transaction will be rolled back and the database will be restored to a state consistent with those rules. On the other hand, if a transaction successfully executes, it will take the database from one state that is consistent with the rules to another state that is also consistent with the rules.


Isolation :

requires that multiple transactions occurring at the same time not impact each other’s execution. For example, if Joe issues a transaction against a database at the same time that Mary issues a different transaction, both transactions should operate on the database in an isolated manner. The database should either perform Joe’s entire transaction before executing Mary’s or vice-versa. This prevents Joe’s transaction from reading intermediate data produced as a side effect of part of Mary’s transaction that will not eventually be committed to the database. Note that the isolation property does not ensure which transaction will execute first, merely that they will not interfere with each other.


Durability :

ensures that any transaction committed to the database will not be lost. Durability is ensured through the use of database backups and transaction logs that facilitate the restoration of committed transactions in spite of any subsequent software or hardware failures.

Comments

Popular posts from this blog

Odoo: Qweb Templates Cache Issue

Hi Everyone, Today I was working on a hotel booking template in Odoo and changes made in the Qweb template(.xml) were not reflecting on updating module with odoo service restart. Tried few times without any success :(. Finally, I decided to delete the old template from Odoo backend and then update module again and it worked like a charm!! :) Steps to delete template from backend: Settings --> User Interface --> Views --> Search by template name Delete the used template. Although it's a small post, but I'm sure it will meet the purpose and help someone in the future. Thanks!!! Enjoy Programming!! :) Reference Links: =================================== https://www.odoo.com/forum/help-1/question/odoo-cache-and-updating-qweb-templates-84492

Odoo12/13: Add an extra action in the tree view action button

This post will help you to add an action window in Odoo. Odoo13: <act_window id="action_make_bank_payment"              name="Do Bank Payment"              res_model="account.ob.payment"              binding_model="account.move"              view_mode="form"              target="new"              binding_views="list,form"              domain="[('type','=', 'in_invoice')]"              groups="account.group_account_user" /> Odoo12: <act_window id="action_make_bank_payment"              name="Do Bank Payment"              res_model="account.ob.payment"             view_mode="tree,form"              domain="[('type','=', 'in_invoice')]"              groups="account.group_account_user" /> Thanks!!! Enjoy Programming!! :) Reference: https://www.odoo.com/es_

Odoo/OpenERP: one2one relational field example

one2one relational field is deprecated in OpenERP version>5 but you can achieve the same using many2one relational field. You can achieve it in following two ways : 1) using many2one field in both the objects ( http://tutorialopenerp.wordpress.com/2014/04/23/one2one/ ) 2)  using inheritance by deligation You can easily find the first solution with little search over internet so let's start with 2nd solution. Scenario :  I want to create a one2one relation between two objects of openerp hr.employee and hr.employee.medical.details What I should do  i. Add _inherits section in hr_employee class ii. Add field medical_detail_id in hr_employee class class hr_employee(osv.osv):     _name = 'hr.employee'     _inherits = {' hr.employee.medical.details ': "medical_detail_id"}     _inherit = 'hr.employee'         _columns = {              'emp_code':fields.char('Employee Code', si