= ; = .The system crashed after log ID 213; no further entries were written.Log-IDTrans-IDRecord200100UPDATE A=0; A=15201100UPDATE B=0; B=15202100COMMIT203101BEGIN204101UPDATΕ A-15;...


Question 4: Write-ahead Log (15)<br>Consider the following portion of a write-ahead log. In this log, UPDATE records are of the form<br>UPDATE <var>=<old value>; <var>=<new value>.<br>The system crashed after log ID 213; no further entries were written.<br>Log-ID<br>Trans-ID<br>Record<br>200<br>100<br>UPDATE A=0; A=15<br>201<br>100<br>UPDATE B=0; B=15<br>202<br>100<br>COMMIT<br>203<br>101<br>BEGIN<br>204<br>101<br>UPDATΕ A-15; A-25<br>205<br>101<br>UPDATE B=15; B=20<br>206<br>102<br>BEGIN<br>207<br>102<br>UPDATE C=0; C=35<br>208<br>102<br>UPDATE D=0; D=20<br>209<br>102<br>СOMMIT<br>210<br>101<br>UPDATE D=20; D=55<br>211<br>101<br>UPDATE B=20; B=65<br>212<br>103<br>BEGIN<br>213<br>103<br>UPDATE C=35; C=70<br>/** CRASH **/<br>1. After recovery, what are the values of A, B, C, and D? If it is impossible to determine the value for any of<br>these variables, write

Extracted text: Question 4: Write-ahead Log (15) Consider the following portion of a write-ahead log. In this log, UPDATE records are of the form UPDATE
=;
=. The system crashed after log ID 213; no further entries were written. Log-ID Trans-ID Record 200 100 UPDATE A=0; A=15 201 100 UPDATE B=0; B=15 202 100 COMMIT 203 101 BEGIN 204 101 UPDATΕ A-15; A-25 205 101 UPDATE B=15; B=20 206 102 BEGIN 207 102 UPDATE C=0; C=35 208 102 UPDATE D=0; D=20 209 102 СOMMIT 210 101 UPDATE D=20; D=55 211 101 UPDATE B=20; B=65 212 103 BEGIN 213 103 UPDATE C=35; C=70 /** CRASH **/ 1. After recovery, what are the values of A, B, C, and D? If it is impossible to determine the value for any of these variables, write "None" in the corresponding parameter. Please explain your answer. 2. Is log portion shown above consistent with a transaction processing system that is using two-phase locking? Explain your answer.
Jun 11, 2022
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