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Thread: Backup question

  1. #1
    Join Date
    Jul 2004
    Posts
    268

    Unanswered: Backup question

    Hi All,

    I have a database backup that was taken at 10:00 pm and a transaction log backup that was taken at 12:00 pm. If I run a database backup at 2:00 pm, the transactions that are in the 12:00 pm transaction log backup will be committed to the database, and I can safely delete the 12:00 pm transaction log backup. Am I right? Thanks.

  2. #2
    Join Date
    Jul 2003
    Location
    San Antonio, TX
    Posts
    3,662
    See scenario below:

    Monday 10PM - full db backup
    Tuesday 12PM - transaction log backup
    Tuesday 2PM - full db backup

    The Tuesday 2PM backup contains transactions backed up at 12PM the same day. If the assumption of your explanation is correct, - then the transaction log backup is not needed if you intend to restore the full backup from 2PM.
    "The data in a record depends on the Key to the record, the Whole Key, and
    nothing but the Key, so help me Codd."

  3. #3
    Join Date
    Jul 2004
    Posts
    268
    Would there be a situation when I want to use Monday 10PM full db backup instead of Tuesday 2PM full db backup for restore? Don't I always want to use the latest db backup?

  4. #4
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    Provided Answers: 1
    The transactions in your backup log are committed anyway.
    A database backup is fully recoverable, and does not require prior logs.
    You may STILL want to keep your logs, because they enable you to perform "point-in-time" restores, which database backups alone do not allow.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  5. #5
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    Provided Answers: 1
    Quote Originally Posted by inka
    Would there be a situation when I want to use Monday 10PM full db backup instead of Tuesday 2PM full db backup for restore? Don't I always want to use the latest db backup?
    See my above response. You should keep a cycle of backups and logs to allow you to perform point-in-time data recovery. For those times when the accounting department tells you "we just found out today that we goofed up last week".
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

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