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Exam 1z0-083 topic 1 question 142 discussion

Actual exam question from Oracle's 1z0-083
Question #: 142
Topic #: 1
[All 1z0-083 Questions]

Which three are true about the FLASHBACK DATABASE feature? (Choose three.)

  • A. FLASHBACK LOGS are archived after a log switch.
  • B. A database can be flashed back using SQL*PLUS.
  • C. Queries and DML have the same FLASHBACK LOG overhead when flashback is enabled for a database.
  • D. FLASHBACK DATABASE only uses FLASHBACK LOGS to get the database to the desired flashback time.
  • E. It always generates REDO and UNDO.
  • F. It requires that the target database be in ARCHIVELOG mode.
Show Suggested Answer Hide Answer
Suggested Answer: BCF 🗳️

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mporislav
Highly Voted 2 years, 12 months ago
B, E, F agree with ObserverPL: 19c docs: Queries do not change data and thus do not contribute to logging activity for Flashback Database. (Not C)
upvoted 12 times
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antonica
Most Recent 1 month, 3 weeks ago
flashback, use archive log: see "Changes between the last flashback log and the target time must be re-created based on the archived redo log. If no automatic channels are allocated for tape and a needed redo log is on tape, then the FLASHBACK DATABASE operation fails."
upvoted 1 times
antonica
1 month, 3 weeks ago
BEF for me.
upvoted 1 times
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dancymonkey
4 months ago
BDF Why D? https://docs.oracle.com/en/database/oracle/oracle-database/19/rcmrf/FLASHBACK-DATABASE.html#GUID-584AC79A-40C5-45CA-8C63-DED3BE3A4511:~:text=You%20must%20enable%20flashback%20logging%20before%20the%20target%20time%20for%20flashback%20by%20issuing%20the%20SQL%20statement%20ALTER%20DATABASE%20...%20FLASHBACK%20ON. You must enable flashback logging before the target time for flashback by issuing the SQL statement ALTER DATABASE ... FLASHBACK ON.
upvoted 1 times
jonsnoow
1 month ago
Archived redo log files are also used: "RMAN uses flashback logs to undo changes to a point before the target time or SCN. RMAN automatically restores from backup any archived redo log files that are needed and recovers the database to make it consistent"
upvoted 1 times
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dancymonkey
3 months, 3 weeks ago
Database mounted. SQL> ALTER DATABASE ARCHIVELOG; Database altered. SQL> ALTER DATABASE OPEN; SQL> ALTER DATABASE FLASHBACK ON; ALTER DATABASE FLASHBACK ON * ERROR at line 1: ORA-38706: Cannot turn on FLASHBACK DATABASE logging. ORA-38709: Recovery Area is not enabled. SQL> ALTER SYSTEM SET DB_RECOVERY_FILE_DEST='/tmp' SCOPE=BOTH; System altered. SQL> ALTER SYSTEM SET DB_RECOVERY_FILE_DEST_SIZE=1G SCOPE=BOTH; System altered. SQL> ALTER DATABASE FLASHBACK ON; Database altered.
upvoted 1 times
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Kuraudio
4 months, 2 weeks ago
Selected Answer: BDF
D: "The database must be mounted, but not open, with a current control file. "
upvoted 1 times
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piontk
8 months, 2 weeks ago
Selected Answer: BDF
Well, E is wrong. One prerequisite for FLASHBACK DATABASE is that the database "must be mounted with a current control file". When mounted the redo log files are not online, and redo cannot be written to it. REF: https://docs.oracle.com/en/database/oracle/oracle-database/19/rcmrf/FLASHBACK-DATABASE.html#GUID-584AC79A-40C5-45CA-8C63-DED3BE3A4511 In another point of the documentation, when using SQL*Plus: "Oracle Flashback Database returns your entire database or an entire PDB to a previous state without requiring you to restore files from backup." REF: https://docs.oracle.com/en/database/oracle/oracle-database/19/bradv/user-managed-flashback-dbpitr.html#GUID-2E5F3F62-17ED-472A-ABBD-FAAF107C6852 Going BDF on this one. If this is an actual question we can contact Oracle support after the exam to point this point.
upvoted 2 times
JaredC
5 months, 3 weeks ago
Thats the thing. they dont tell you if you are right or wrong on which questions. (unless you only wrong on few questions which you can *guess* which one you might be wrong based on the topic)
upvoted 1 times
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_gio_
10 months, 2 weeks ago
Selected Answer: BEF
Sure of BEF
upvoted 1 times
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ErikJanssen
11 months, 1 week ago
I think answer BEF too. B: You can use sqlplus for FLASHBACK DATABASE. https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/FLASHBACK-DATABASE.html#GUID-BE0ACF9A-BC13-4810-B08B-33326440258B
upvoted 1 times
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ScottL
1 year ago
Selected Answer: BEF
B,E,F per ObserverPL
upvoted 1 times
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DBA007
2 years, 2 months ago
Answer: B,D,F "Flashback Database can only be used if flashback logs are available." "Any remaining changes are recovered using online and archived redo logs if available." https://blogs.oracle.com/maa/post/flashback-database-and-flashback-logs#:~:text=Flashback%20Database%20can%20only%20be,target%20to%20use%20Flashback%20Database.
upvoted 2 times
FeaRoX
2 years, 1 month ago
as per your justification - not ONLY flashback logs are used each time.
upvoted 2 times
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rodriguesJC
2 years, 6 months ago
B is False: "You can run this command from the RMAN prompt or from within a RUN command." https://docs.oracle.com/en/database/oracle/oracle-database/19/rcmrf/FLASHBACK-DATABASE.html#GUID-584AC79A-40C5-45CA-8C63-DED3BE3A4511
upvoted 2 times
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nobody347
2 years, 7 months ago
About C The overhead of logging for Flashback Database depends on the mixture of reads and writes in the database workload. When you have a write-intensive workload, the Flashback Database logging overhead is high since it must log all those database changes. Queries do not change data and thus do not contribute to logging activity for Flashback Database.
upvoted 2 times
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nobody347
2 years, 8 months ago
I think B is wrong. RMAN have to be used to flashback datatabase
upvoted 2 times
G_C
1 year, 7 months ago
You are wrong. RMAN can be used for that as well as SQL*Plus do not follow an examples from official documentation because it just an example.
upvoted 1 times
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ObserverPL
2 years, 12 months ago
A is wrong - they are never archived B is CORRECT, C is wrong - why queries would have FLASHBACK LOG overhead? only DMLs generate FLASHBACK LOGs D is wrong - according to documentation and my practice some ARCHIVE LOGs are required too E - no idea... F is CORRECT. ... so the only option seems to be BEF
upvoted 4 times
7206e44
3 weeks ago
undo generates redo, which in turn generates flashback entry. I don't think it works the other way around
upvoted 1 times
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guretto
5 months ago
E All logical flashback features except Flashback Drop rely on undo data (https://docs.oracle.com/cd/E15586_01/backup.1111/e10642/rcmflash.htm)
upvoted 1 times
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RinD
3 years ago
BCF correct
upvoted 1 times
G_C
1 year, 7 months ago
Can you clarify why do you think that queries generate FLASHBACK LOG? I think it is true FLASHBACK DATA ARCHIVE but it is different feature than FLASHBACK DATABASE.
upvoted 1 times
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A (35%)
C (25%)
B (20%)
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