ACID Properties
Transactions follows the acid properties which is a short form of Atomicity, Consistency, Isolation, Durability (ACID).The Acid properties of transaction are defined below:
1. Atomicity
We can remember about this using a single line that is, “Either full or none”. It means that a transaction will either execute all operations or none i.e. either a transaction will get completed or it will not take place. It is maintained using recovery subsystem.
2. Consistency
It means that our database should be consistent throughout the transaction. It is maintained by either by user or programmer. We can see the consistency in the below mentioned example.
Example:
Consider two persons A and B
Balance in A’s account = 1000;
Balance in B’s account = 500 ;
Sum of A and B account balance = 1500;
Now consider if A transfers 100 rupees to B then their new balance will be
A’s account balance = 900;
B’s account balance = 600;
Sum of A and B account balance after transfer = 1500
So, from the above example we can say that the total amount in A and B account remained consistent throughout the transaction.
3. Isolation
The word isolation in general means, “The state of being separate or alone”. In DBMS Two or more transaction in parallel execution will take place separately or independently. It is maintained using concurrency system.
4. Durability
It is derived from the word durable which means, “likely to last for a long time”. The modification done in the database during a transaction should stay for a long period of time. It should remain the same even if the system fails. It is maintained using recovery subsystem. When a transaction takes place it goes through a number of states.
Cascading Rollback
Cascading rollback is a term that is used in DBMS. It is a concept that is explained in DBMS when we start discussing transactions.
So, let’s discuss briefly the basics that we require to know before studying cascading rollback.
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