Transaction and ACID properties

A set of statements executed on a resource or resources applied with ACID properties is known as Transaction.

Note: Here database is one resource but resource need not be only database

ACID Properties:

  • Atomicity
  • Consistency
  • Isolation
  • Durability

This property describes that the set of statements involved in the transaction has to work as a single unit (i.e, automic). This is the minimum requirement that has to be met for a transaction

If the data used in the transaction is consistent before starting the transaction, then it has to be left in a consistent state even after the transaction.
Note: What is consistent data: data applied with some rules.

accountNo | accountBal
101        | 6000

Here lets define a rule that says if: accountBal>5000; then it is said to be in consistent state.
so before transaction it is 6000 and after transaction lets say it has become 8000, then it is left in consistent state. If it falls below 5000, ie, lets say 4000, then it is said to be inconsistent state in which case we will rollback the transaction

And if the data used in the transaction is already in inconsistent state then we cannot guarantee the consistent data after the transaction.

It is an ability to isolate the data used in one transaction from the other transaction.


Once the transaction starts to save, it should definitely save all the statements within the transaction at any cost else rollback all the statements and throw exception.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


Mostly technology with occasional sprinkling of other random thoughts


Amir Amintabar's personal page

101 Books

Reading my way through Time Magazine's 100 Greatest Novels since 1923 (plus Ulysses)

Seek, Plunnge and more...

My words, my world...

ARRM Foundation

Do not wait for leaders; do it alone, person to person - Mother Teresa

Executive Management

An unexamined life is not worth living – Socrates


A topnotch site


Just another site

coding algorithms

"An approximate answer to the right problem is worth a good deal more than an exact answer to an approximate problem." -- John Tukey

%d bloggers like this: