course hero how are failure and commit controls are achieved in ddbms

What is failure and commit in distributed DBMS?

Distributed DBMS - Failure & Commit. A database management system is susceptible to a number of failures. In this chapter we will study the failure types and commit protocols. In a distributed database system, failures can be broadly categorized into soft failures, hard failures and network failures.

What are the failures of a database management system?

A database management system is susceptible to a number of failures. In this chapter we will study the failure types and commit protocols. In a distributed database system, failures can be broadly categorized into soft failures, hard failures and network failures.

Can the modifications brought about by the database be seen by others?

At this point, the modifications brought about by the database can be seen by the other transactions. All transactions can have a consistent view of the database.

What happens when a database transaction fails?

Any database system should guarantee that the desirable properties of a transaction are maintained even after failures. If a failure occurs during the execution of a transaction, it may happen that all the changes brought about by the transaction are not committed. This makes the database inconsistent.

What happens if a database fails?

If a failure occurs during the execution of a transaction, all the changes that the transaction brings in will not be committed. It renders the database inconsistent. Commit protocols avoid using either transaction undo (rollback) or transaction redo (roll forward) in this scenario.

What is the process of undoing all the changes that a transaction makes to a database called?

The process of undoing all the changes that a transaction makes to a database is called transaction undo or transaction rollback. In the case of soft failure, this is often applied.

What type of failure causes data loss in the persistent or non-volatile storage like disk?

The type of failure causing data loss in the persistent or non-volatile storage like disk is a hard failure. Disk failure may cause data corruption in some disk blocks or total disk failure. The causes of a difficult failure are—

What is soft failure?

Soft failure is the type of failure that causes the loss of the computer's volatile memory rather than persistent storage. The stored data in non-persistent storage, such as main memory, buffers, caches or records, is lost here. They are also known as system crash. The various types of soft failures are as follows −

How many types of lists are there in a transaction log?

Depending on the status of the transaction, the transaction log maintains five types of lists. This list helps the recovery manager to determine a transaction 's status. The following are the status and the corresponding lists