Key terms related to recovery

There are many internal structures that play a very important role in the recovery of the database and also in its internal workings. In the following list, we shall look at the most important key terms which are a must for you to understand:

• Data block: It is the smallest unit among the storage structures of the database and is used for storing user data. An example is the infamous table EMP which contains the employee data. Thus, for an employee AMAN, block #100, for example, would contain the data in the form of a row belonging to it.

• Dirty block: When a database block's content is modified by a DML, as long as that transaction is not completed with either a ROLLBACK or COMMIT command, the data is termed as inconsistent and correspondingly, that block is marked as a dirty block. A dirty block would need to have its transaction status updated with either a ROLLBACK or COMMIT command to finally become a clean block.

• Change vectors: The changes done over the...