Time Action Record Updated Before Image After Image 10:00 Start 10:01 Start 10:02 Insert Session (39) (new values) 10:03 Start 10:04 Update Therapist JRO85) (old values) (new values) 10:05 Update Patient (1012) (old values) |(new values) 10:06 Commit

Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
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2. Suppose a catastrophe destroys the database just after 10:10. Which transactions in the sample log shown in Figure 7-19 would the recovery program use to
update the restored database? Which transactions would have to be entered again by users?
Transaction ID
Time
Action
Record Updated
Before Image
After Image
1
10:00
Start
2.
10:01
Start
1
10:02
Insert
Session (39)
(new values)
3.
10:03
Start
10:04
Update
Therapist (JRO85)
(old values)
(new values)
3
10:05
Update
Patient (1012)
(old values)
(new values)
1
10:06
Commit
10:07
Start
10:08
Update
Therapies (92540)
(old values)
(new values)
3.
10:09
Commit
10:10
Update
Therapies (92540)
(old values)
(new values)
2.
10:11
Commit
4
10:12
Update
Therapies (92540)
(old values)
(new values)
4
10:13
Update
Patient (1012)
(old values)
(new values)
4.
10:14
Commit
FIGURE 7-19 Sample log in which four transactions commit normally
Transcribed Image Text:2. Suppose a catastrophe destroys the database just after 10:10. Which transactions in the sample log shown in Figure 7-19 would the recovery program use to update the restored database? Which transactions would have to be entered again by users? Transaction ID Time Action Record Updated Before Image After Image 1 10:00 Start 2. 10:01 Start 1 10:02 Insert Session (39) (new values) 3. 10:03 Start 10:04 Update Therapist (JRO85) (old values) (new values) 3 10:05 Update Patient (1012) (old values) (new values) 1 10:06 Commit 10:07 Start 10:08 Update Therapies (92540) (old values) (new values) 3. 10:09 Commit 10:10 Update Therapies (92540) (old values) (new values) 2. 10:11 Commit 4 10:12 Update Therapies (92540) (old values) (new values) 4 10:13 Update Patient (1012) (old values) (new values) 4. 10:14 Commit FIGURE 7-19 Sample log in which four transactions commit normally
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