What are log-based recovery techniques?

The log is a sequence of records. Log of each transaction is maintained in some stable storage so that if any failure occurs, then it can be recovered from there. If any operation is performed on the database, then it will be recorded in the log.

What are different types of log-based recovery in DBMS?

Immediate database modification Update log records maintain both old and new values of data items. Undo(Ti) − All data items updated by the transaction Ti, are set to old value. Redo(Ti) − All data items updated by the transaction Ti are set to a new value.

What is meant by log-based recovery schemes explain the types of log-based schemes in detail with appropriate examples?

Atomicity property of DBMS states that either all the operations of transactions must be performed or none. The modifications done by an aborted transaction should not be visible to database and the modifications done by committed transaction should be visible.

What is checkpoint and log recovery?

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 are the two different methods that are used in log based recovery explain with an example?

Undo: using a log record sets the data item specified in log record to old value. Redo: using a log record sets the data item specified in log record to new value.

What are the recovery techniques?

Methods to Enhance Recovery Some of the most popular recovery techniques for athletes include hydrotherapy, active recovery, stretching, compression garments, massage, sleep and nutrition.

How many types of recovery techniques are in database?

There are three basic types of recovery: instance recovery, crash recovery, and media recovery.

Which of the following are introduced to reduce the overhead caused by log-based recovery?

Checkpoints
3. Which of the following are introduced to reduce the overheads caused by the log-based recovery? Explanation: Checkpoints are introduced to reduce overheads caused by the log-based recovery.

What is a system log What is the purpose of the system log in system recovery?

The system log (syslog) contains a record of the operating system (OS) events that indicates how the system processes and drivers were loaded. The syslog shows informational, error and warning events related to the computer OS.

What are the most important steps of log based recovery algorithms?

Log based Recovery in DBMS

• Log and log records – The log is a sequence of log records, recording all the update activities in the database.
• Undo and Redo Operations –
• The database can be modified using two approaches –
• Recovery using Log records –
• Use of Checkpoints –