Hibernate Interview Questions – Part 5

Hibernate Interview Questions – Part 5
Part 1, Part 2, Part 3, Part 4
Persistent Objects and Transactions

Different Object States in Hibernate?
Transient
Persistent
Detached


Transient:
An object created using new Operator is known in Transient State. This object is not associated with database.

Persistent:
When a Transient object with values are stored in database, then the object is said to be in Persistent State.

Detached State:
When an object is saved in the database and the hibernate session is closed, The object is said to be in Detached State


What is a Transaction?
Transaction is a sequence of operations performed.


Properties of Transactions?
Every transaction should have the following ACID properties,
Atomic : All the modifications to be performed or none to be performed
Consistency: All data should be consistent once the transaction has been completed
Isolation: Every transaction should be Isolated from another transaction
Durability: Data change in a system after the transaction is completed should remain permanent in the System.


States of Transactions:
Active:
when transaction is created and ready for execution.

Partially Committed:
When all the operations are performed but the transaction is not yet committed.

Failed:
When transaction is failed and cannot proceed further.

Aborted:
Transaction is failed and the operations of transactions are rolled back.

Committed:
Transaction is success and all the changes are committed and saved in database.

Terminated:
When transaction is completed successfully or when transaction is failed this state occurs.


Methods to Configure Transactions:
void begin():
Starts the transaction.

void commit():
Ends the work.

void rollback():
Reverse the changes.

boolean wasCommitted():
checks whether the transaction is committed or not.

boolean wasRolledBack():
checks if transaction is rolledback or not.


 

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