Question

Which lock should be obtained to prevent a concurrent transaction from executing a conflicting read, insert or delete operation on the same key value. (a) Higher-level lock (b) Lower-level lock (c) Read only lock (d) Read write I have been asked this question by my school principal while I was bunking the class. Question is from Lock Release and Undo Operations in division Recovery System of Database Management Select the correct answer from above options Interview Questions and Answers, Database Interview Questions and Answers for Freshers and Experience

Answer 1

Correct option is (a) Higher-level lock To explain: Operations acquire lower-level locks while they execute, but release them when they complete; the corresponding transaction must however retain a higher-level lock in a two-phase manner to prevent concurrent transactions from executing conflicting actions.