Interested to Buy Any Domain ? << Click Here >> for more details...
What is a transaction and what are ACID properties?
- 14 Answers
- 77345 Views
- Config Systems, IBM, TCS, Virtusa, I also Faced
- E-Mail Answers
Answer Posted / sumit jha
A transaction can be defined as a group of tasks. A single task is the minimum processing unit which cannot be divided further.
Let’s take an example of a simple transaction. Suppose a bank employee transfers Rs 500 from A's account to B's account. This very simple and small transaction involves several low-level tasks.
A’s Account
Open_Account(A)
Old_Balance = A.balance
New_Balance = Old_Balance - 500
A.balance = New_Balance
Close_Account(A)
B’s Account
Open_Account(B)
Old_Balance = B.balance
New_Balance = Old_Balance + 500
B.balance = New_Balance
Close_Account(B)
ACID Properties
A transaction is a very small unit of a program and it may contain several lowlevel tasks. A transaction in a database system must maintain Atomicity, Consistency, Isolation, and Durability − commonly known as ACID properties − in order to ensure accuracy, completeness, and data integrity.
• Atomicity − This property states that a transaction must be treated as an atomic unit, that is, either all of its operations are executed or none. There must be no state in a database where a transaction is left partially completed. States should be defined either before the execution of the transaction or after the execution/abortion/failure of the transaction.
• Consistency − The database must remain in a consistent state after any transaction. No transaction should have any adverse effect on the data residing in the database. If the database was in a consistent state before the execution of a transaction, it must remain consistent after the execution of the transaction as well.
• Durability − The database should be durable enough to hold all its latest updates even if the system fails or restarts. If a transaction updates a chunk of data in a database and commits, then the database will hold the modified data. If a transaction commits but the system fails before the data could be written on to the disk, then that data will be updated once the system springs back into action.
• Isolation − In a database system where more than one transaction are being executed simultaneously and in parallel, the property of isolation states that all the transactions will be carried out and executed as if it is the only transaction in the system. No transaction will affect the existence of any other transaction.
| Is This Answer Correct ? | 1 Yes | 0 No |
Post New Answer View All Answers
How to use subqueries with the in operators in ms sql server?
How many columns can we include on clustered index ?
What is a dbms wizard?
How can i Relate Tables in SSIS
you have separate development and production systems you want to move a copy of a development database into production to do this, you do a backup on the development system and restore to the production system after a few minutes, you begin getting calls from several customers saying that they are denied access to the system why? : Sql server administration
Difference between connected and disconnected database in .net with sql server?
What is the preferred way to create a clustered and non-clustered index? Which index should you create first the clustered or non-clustered?
Can two tables share the same primary key?
What is the difference between implicit and explicit transaction?
Can sql servers linked to other servers?
What is difference between equi join and inner join?
Why we use functions in sql server?
What is multi-statement table-value user-defined function?
How to create a store procedure with encryption?
How to connect a database with sql express.?
