Backup and recovery describes the process of creating and storing copies of data that can be used to protect organizations against data loss. This is sometimes referred to as operational recovery.
What is database recovery and backup?
Recovery in general refers to the various operations involved in restoring, rolling forward, and rolling back a backup. Backup and recovery in general refers to the various strategies and operations involved in protecting your database against data loss and reconstructing the data should that loss occur.
What is difference between backup and recovery?
In a nutshell, the primary difference between backup and recovery is that the former is a copy of original data that can be used in case of a database failure while recovery refers to the process of restoring your database to its correct (original) state when a failure occurs.
What is backup in DBMS?
Database backup is the process of backing up the operational state, architecture and stored data of database software. It enables the creation of a duplicate instance or copy of a database in case the primary database crashes, is corrupted or is lost.
What is recovery in DBMS?
Recovery is the process of restoring a database to the correct state in the event of a failure. It ensures that the database is reliable and remains in consistent state in case of a failure. Database recovery can be classified into two parts; 1. Rolling Forward applies redo records to the corresponding data blocks.
What is the difference between backup and recovery give examples of each?
Backup refers to storing a copy of original data which can be used in case of data loss.
Difference between Backup and Recovery :
|09.||Example of Backup can be SnapManager makes a backup of everything in database.||Example of Recover can be SnapManager recovers the data to the last transaction.|
What are the 3 types of backups?
The most common backup types are a full backup, incremental backup and differential backup. Other backup types include synthetic full backups and mirroring.
Why recovery is important in DBMS?
If such a failure affects the operation of a database system, you must usually recover the database and return to normal operation as quickly as possible. Recovery should protect the database and associated users from unnecessary problems and avoid or reduce the possibility of having to duplicate work manually.
Why do we use recovery in DBMS?
Database recovery management or recovery system in DBMS help to recover the failure. Include memory errors, disk problems, crashes, bad sectors, etc. Include software failures such as DBMS software, O.S., application programming, etc. A system failure can occur due to hardware/software/power failure.
What is deadlock in DBMS?
In a database, a deadlock is a situation in which two or more transactions are waiting for one another to give up locks. For example, Transaction A might hold a lock on some rows in the Accounts table and needs to update some rows in the Orders table to finish.
What is checkpoint in DBMS?
Checkpoint is a mechanism where all the previous logs are removed from the system and stored permanently in a storage disk. Checkpoint declares a point before which the DBMS was in consistent state, and all the transactions were committed.
What is starvation in DBMS?
Starvation or Livelock is the situation when a transaction has to wait for an indefinite period of time to acquire a lock.
What is anomaly in DBMS?
Database anomaly is normally the flaw in databases which occurs because of poor planning and storing everything in a flat database. Generally this is removed by the process of normalization which is performed by splitting/joining of tables.
What is Normalisation?
What Does Normalization Mean? Normalization is the process of reorganizing data in a database so that it meets two basic requirements: There is no redundancy of data, all data is stored in only one place. Data dependencies are logical,all related data items are stored together.
What is trivial and non trivial dependency?
Trivial Functional Dependency
Trivial − If a functional dependency (FD) X → Y holds, where Y is a subset of X, then it is called a trivial FD. Trivial FDs always hold. Non-trivial − If an FD X → Y holds, where Y is not a subset of X, then it is called a non-trivial FD.
What are the 3 anomalies?
There are three types of anomalies: update, deletion, and insertion anomalies.
What are schemas in DBMS?
The database schema is a structure of a database described in a formal language supported by the database management system (DBMS). The term “schema” refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases).
What is normalization in SQL?
Normalization is the process to eliminate data redundancy and enhance data integrity in the table. Normalization also helps to organize the data in the database. It is a multi-step process that sets the data into tabular form and removes the duplicated data from the relational tables.
What is deletion anomaly in DBMS?
Deletion Anomaly. A deletion anomaly occurs when you delete a record that may contain attributes that shouldn’t be deleted. For instance, if we remove information about the last account at a branch, such as account A-101 at the Downtown branch in Figure 10.4, all of the branch information disappears.
What is normalization and anomalies?
Normalization is the process of structuring and handling the relationship between data to minimize redundancy in the relational table and avoid the unnecessary anomalies properties from the database like insertion, update and delete.
What is storage redundancy?
Data redundancy refers to the practice of keeping data in two or more places within a database or data storage system. Data redundancy ensures an organization can provide continued operations or services in the event something happens to its data — for example, in the case of data corruption or data loss.
What is 3NF in DBMS?
It is a normalization level in DBMS. A relation is said to be in 3rd normal form in DBMS (or 3NF) when it is in the second normal form, but no transitive dependency exists for a non-prime attribute.
What is BCNF in DBMS?
Boyce–Codd normal form (or BCNF or 3.5NF) is a normal form used in database normalization. It is a slightly stronger version of the third normal form (3NF). BCNF was developed in 1974 by Raymond F. Boyce and Edgar F. Codd to address certain types of anomalies not dealt with by 3NF as originally defined.
What is 1NF 2NF and 3NF?
A relation is in 1NF if it contains an atomic value. 2NF. A relation will be in 2NF if it is in 1NF and all non-key attributes are fully functional dependent on the primary key. 3NF. A relation will be in 3NF if it is in 2NF and no transition dependency exists.