Explain what is meant by the term Recovery with respect to a DBMS (Database
DBMS is a highly complex system with thousands of transactions carried out every second.
Reasons for DBMS failure can be-
Recovery in respect to DBMS means when a DBMS crashes/fails we need to recover it
When a DBMS recovers from a crash it should maintain ACID properties such as-
1- It should check the states of the transaction, which were being executed
2-A transaction can be in the middle when DBMS would have failed so on recovery DBMS must ensure the Atomicity in that case
There are two types of techniques, which can help a DBMS in recovering as well as maintaining the atomicity of a transaction −
- Maintaining the logs of each transaction, and writing them onto some stable storage before actually modifying the database.
- Maintaining shadow paging, where the changes are done on a volatile memory, and later, the actual database is updated.