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What are the salient features of deferred database modification and immediate database modification schemes for recovery?
In deffered database the transaction is committed after the transaction is completed i.e(the transaction has completed its partially committed state) where as for immediate database the transaction is commited when tha transaction is in the active state. keta shah Oracle DBA track trainer ITS knp_shah@yahoo.co.in
What is transaction system in dbms?
any change in database is called transaction.
Why database integrity?
Database integrity ensures that data stored in the database is accurate and reliable. It helps prevent data corruption, inconsistencies, and errors by enforcing rules and constraints. Maintaining database integrity ensures that the information remains trustworthy and can be relied upon for decision-making processes.
Describe the database recovery process and the use of deferred-write and write-through techniques?
deferred-write: The transaction do not immediate update database, instead, only update log file. Then when transaction reach commit point, it will update the physical database. write-through: The database is update right away during the transaction execution.
What is a database object that allows you to view or print formatted information but not enter data?
Database transaction
Is database checkpoint may increase transaction execution time?
No
What is a transaction in a data base system?
Like transaction in banks there are transactions in a database system too like deleting data is also a transaction. Transaction can be recovered using rollback and save point.
What is aTransaction log?
A transaction log is a list of changes done to a database.
What is ACID test in application in database system?
The ACID model is one of the oldest and most important concepts of database theory. It sets forward four goals that every database management system must strive to achieve: atomicity, consistency, isolation and durability. No database that fails to meet any of these four goals can be considered reliable.Let's take a moment to examine each one of these characteristics in detail: * Atomicity states that database modifications must follow an "all or nothing" rule. Each transaction is said to be "atomic." If one part of the transaction fails, the entire transaction fails. It is critical that the database management system maintain the atomic nature of transactions in spite of any DBMS, operating system or hardware failure. * Consistencystates that only valid data will be written to the database. If, for some reason, a transaction is executed that violates the database's consistency rules, the entire transaction will be rolled back and the database will be restored to a state consistent with those rules. On the other hand, if a transaction successfully executes, it will take the database from one state that is consistent with the rules to another state that is also consistent with the rules. * Isolation requires that multiple transactions occurring at the same time not impact each other's execution. For example, if Joe issues a transaction against a database at the same time that Mary issues a different transaction, both transactions should operate on the database in an isolated manner. The database should either perform Joe's entire transaction before executing Mary's or vice-versa. This prevents Joe's transaction from reading intermediate data produced as a side effect of part of Mary's transaction that will not eventually be committed to the database. Note that the isolation property does not ensure which transaction will execute first, merely that they will not interfere with each other. * Durability ensures that any transaction committed to the database will not be lost. Durability is ensured through the use of database backups and transaction logs that facilitate the restoration of committed transactions in spite of any subsequent software or hardware failures. Take a few minutes to review these characteristics and commit them to memory. If you spend any significant portion of your career working with databases, you'll see them again and again. They provide the basic building blocks of any database transaction model.
What are the component of DDBMS?
The components of a Disributed DataBase Management System (DDBMS) are the Database Manager, the User Interface Request, and a Distributed Transaction Manager.
What is consistency in DBMS?
In SQL data consistency is that whenever a transaction is performed, it sees a consistent database. During the transaction, if the database is not consistent, then there are two reasons for it, which are as follows: 1-database failure (software or hardware failure) 2-multiple accesses data consistency makes sure data integrity and vice versa. :)
How does two phase commit process work in distributed database?
Pretty much the same way it works in any type of architecture. If it's distributed it just means it can span multiple databases of different types. Database changes required by a transaction are initially stored temporarily by each database. The transaction monitor then issues a "pre-commit" command to each database which requires an acknowledgement. If the monitor receives the appropriate response from each database, the monitor issues the "commit" command, which causes all databases to simultaneously make the transaction changes permanent.
