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1Z0-060 · Question #221

The current system change number (SCN) for a live database is 663571. You decide to use the FLASHBACK TABLE statement to flash back the CUSTOMERS table to SCN 662116. After flashing back the…

The correct answer is B. Execute another FLASHBACK TABLE statement to restore the CUSTOMERS table to SCN. To undo a FLASHBACK TABLE operation, issuing another FLASHBACK TABLE statement targeting the original SCN is the fastest method because it is an online, in-place operation requiring no downtime.

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Question

The current system change number (SCN) for a live database is 663571. You decide to use the FLASHBACK TABLE statement to flash back the CUSTOMERS table to SCN 662116. After flashing back the CUSTOMERS table, you query it and decide to undo the effects of the FLASHBACK TABLE command. Which is the fastest way to do this?

Options

  • AExecute the RMAN RECOVER BLOCK command by specifying the table name and SCN 663571
  • BExecute another FLASHBACK TABLE statement to restore the CUSTOMERS table to SCN
  • CPerform table point-in-time recovery because FLASHBACK TABLE cannot be performed on a
  • DPerform tablespace point-in-time recovery because FLASHBACK TABLE cannot be performed on

How the community answered

(46 responses)
  • A
    13% (6)
  • B
    80% (37)
  • C
    2% (1)
  • D
    4% (2)

Why each option

To undo a FLASHBACK TABLE operation, issuing another FLASHBACK TABLE statement targeting the original SCN is the fastest method because it is an online, in-place operation requiring no downtime.

AExecute the RMAN RECOVER BLOCK command by specifying the table name and SCN 663571

RMAN RECOVER BLOCK is a block media recovery command designed to repair physically corrupt data blocks using archived logs, not a mechanism to reverse a logical FLASHBACK TABLE operation.

BExecute another FLASHBACK TABLE statement to restore the CUSTOMERS table to SCNCorrect

FLASHBACK TABLE uses undo data to move a table forward or backward in time without taking the database offline; flashing the CUSTOMERS table back to SCN 663571 (the pre-flashback state) reverses the prior operation instantly and is far faster than any recovery-based alternative that requires additional RMAN or tablespace operations.

CPerform table point-in-time recovery because FLASHBACK TABLE cannot be performed on a

Table point-in-time recovery (DBPITR) requires taking the affected tablespace offline, restoring from backup, and applying redo - a multi-step offline process far slower than a simple FLASHBACK TABLE command.

DPerform tablespace point-in-time recovery because FLASHBACK TABLE cannot be performed on

Tablespace point-in-time recovery is even more disruptive than table PITR, requiring the entire tablespace to be taken offline and recovered, making it the least efficient option for reversing a flashback operation.

Concept tested: Reversing Flashback Table using SCN-based flashback

Source: https://docs.oracle.com/en/database/oracle/oracle-database/19/bradv/using-oracle-flashback-technology.html

Topics

#FLASHBACK TABLE#SCN#flashback undo#point-in-time recovery

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