This is the story of 6 transactions as seen the database change logs. The Action

Question

This is the story of 6 transactions as seen the database change logs. The Action Key below explains how to interpret the entries in the sample logs below. These questions are limited entries in the logs. Assume this is a correct and serializable schedule with appropriate interleaved reads and writes that do NOT cause anomalies. Answer all the following questions based on the log shown below: Answer all the following questions: a) What is the status of the Transactions above at Arrow 1? b) What is the status of the Transactions above at Arrow 2? c) Which transactions were active at Arrow3? d) If you restored the database and applied the log up to the CK at Arrow 2 what would you have to do next to complete the recovery? e) If the database followed the immediate Update protocol what actions must be taken for Transaction 5 when the system crashed at Arrow 3? f) For immediate Update Protocol, changes are written to the database only BEFORE or AFTER a Commit? g) For Deferred Update Protocol, changes are written to the database only BEFORE or AFTER a Commit?

Explanation / Answer

Trans# - 1,3,6

8.e) There is no action needed to taken for Trans#5 becasuse it doesnt commit the updates so no need to take any action

8.a) Status of the Transcation at Arrow #1 Tran# Actions done so far. 1 Begin Record 2 Begin,Update and commit Record 3 Begin Record 4 Begin Record 5 Not Initiated 6 Not Initiated 8.b) Status of the Transcation at Arrow #2 Tran# Actions done so far. 1 Begin Record 2 Begin,Update and commit Record 3 Begin and Update Record 4 Begin Record 5 Begin,Update and AbortRecord 6 Not Initiated 8.c) Active Transcations at Arrow #3

Trans# - 1,3,6

8.e) There is no action needed to taken for Trans#5 becasuse it doesnt commit the updates so no need to take any action

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