70-518 · Question #56
70-518 Question #56: Real Exam Question with Answer & Explanation
The correct answer is A. one transaction in the end => Yes. Pessimistic: In Pessimistic concurrency control a transaction blocks data access operations of other transactions upon conflicts, and conflicts are non-materialized until blocking is removed. This to ensure that operations that may violate serializability (and in practice also re
Question
Options
- Aone transaction in the end => Yes
- BWorks but to many transactions => otut
- Cnon-transactional operations: users should not blocked from reading data => out
- Doptimistic concurrency for each page-- we need one operation for all pages =>out
Explanation
Pessimistic: In Pessimistic concurrency control a transaction blocks data access operations of other transactions upon conflicts, and conflicts are non-materialized until blocking is removed. This to ensure that operations that may violate serializability (and in practice also recoverability) Optimistic: In Optimistic concurrency control data access operations of other transactions are not blocked upon conflicts, and conflicts are immediately materialized. When the transaction reaches the ready state, i.e., its running state has been completed, possible serializability (and in practice also recoverability) violation by the transaction's operations (relatively to other running transactions) is checked: If violation has occurred, the transaction is typically aborted (sometimes aborting another transaction to handle serializability violation is preferred). Otherwise it is committed.
Community Discussion
No community discussion yet for this question.