11Which ACID property ensures a transaction is all-or-nothing?ADurabilityBAtomicityCIsolationDConsistencyView AnswerDiscussWorkspaceReportSaveEasy
12Which technique avoids locks by checking for conflicts at commit time?AOptimistic concurrency controlBDeadlock detectionCStrict orderingDTwo-phase lockingView AnswerDiscussWorkspaceReportSaveEasy
13A non-repeatable read occurs when:AA row read twice in one transaction returns different valuesBA query returns new rowsCA row is lockedDA transaction reads its own writesView AnswerDiscussWorkspaceReportSaveEasy
14Write-ahead logging means:ALog records are written before the data changes reach diskBNo log is keptCData is written before the logDLogs are written after commit onlyView AnswerDiscussWorkspaceReportSaveEasy
15Two-phase locking (2PL) guarantees:AConflict-serializable schedulesBNo deadlocksCFaster commitsDNo locking at allView AnswerDiscussWorkspaceReportSaveMedium