1Z0-873 · Question #35
Which of the following correctly defines dirty reads, non-repeatable reads and phantom row?
The correct answer is A. A dirty read is a read by one transaction of uncommitted changes made by another transaction. C. A non-repeatable read occurs when a transaction performs the same retrieval twice but gets a E. A phantom is a row that appears where it was not visible before. A: A dirty read occurs when a transaction is allowed to read data from a row that has been modified by another running transaction and not yet committed. C: A non-repeatable read occurs, when during the course of a transaction, a row is retrieved twice and the values within the…
Question
Which of the following correctly defines dirty reads, non-repeatable reads and phantom row?
Options
- AA dirty read is a read by one transaction of uncommitted changes made by another transaction.
- BA dirty read is a read by one transaction of its uncommitted changes.
- CA non-repeatable read occurs when a transaction performs the same retrieval twice but gets a
- DA non-repeatable read is a row that appears where it was not visible before.
- EA phantom is a row that appears where it was not visible before.
- FA phantom is a read by one transaction of uncommitted changes made by another transaction.
How the community answered
(15 responses)- A73% (11)
- B7% (1)
- D7% (1)
- F13% (2)
Explanation
A: A dirty read occurs when a transaction is allowed to read data from a row that has been modified by another running transaction and not yet committed. C: A non-repeatable read occurs, when during the course of a transaction, a row is retrieved twice and the values within the row differ between reads. A phantom read occurs when, in the course of a transaction, two identical queries are executed, and the collection of rows returned by the second query is different from the first. The phantom reads anomaly is a special case of Non-repeatable reads
Topics
Community Discussion
No community discussion yet for this question.