Which of the following statement are correct? (Choose all correct answers.) A. Undo data protects against data loss. B. Redo data is used for rolling forward database changes. C. Redo data is used for read consistency. D. Undo data is used for read consistency.
Question
Which of the following statement are correct? (Choose all correct answers.) A. Undo data protects against data loss. B. Redo data is used for rolling forward database changes. C. Redo data is used for read consistency. D. Undo data is used for read consistency.
Solution
The correct statements are:
B. Redo data is used for rolling forward database changes. This is because redo logs contain a record of changes made to data, which can be used to reconstruct all changes made to a database since a certain point in time.
D. Undo data is used for read consistency. Undo data is used to store old data values that have been changed by SQL statements. This allows users to see a consistent view of the data as it was at the beginning of their operation, even if other users are changing the data at the same time.
Similar Questions
Which of the following data structures is typically used for undo and redo operations in applications like text editors?Group of answer choicesCircular linked listPriority linked listSingly linked listDoubly linked list
What are the two types of recovery information mentioned in the text?Undo and redoRedo and savepointUndo and savepointCheckpoint and journal files
Which of the following scenarios may lead to an irrecoverable error in a database system?A transaction reads a data item after it is written by a committed transactionA transaction writes a data item after it is read by an uncommitted transactionA transaction reads a data item after it is written by an uncommitted transactionA transaction reads a data item after it is read by an uncommitted transaction
True or False: Data loss refers to the permanent or temporary unavailability of information and can impact business workflows.
True or false. Data collected for one purpose cannot easily be used for a different purposes in future database management and access systems.
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.