redologs and archivedlogs
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Thread: redologs and archivedlogs

  1. #1
    Join Date
    Jan 2001
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    2,828

    redologs and archivedlogs

    Hi

    How about archiving the contents of logbuffer directly to archived logs,
    instead of writing it to the intermediary store called online redologs and then archiving it to archived redo logs.

  2. #2
    Join Date
    Mar 2006
    Location
    Charlotte, NC
    Posts
    865
    my 2 cents ...

    as par Oracle architecture, log buffer size should be 4MB or few more MBs more. In this case, there will be hundreds of archive logs will generate every hour which is very I/O expensive.

    as we don't have groups in log buffer, transactions has to wait till the current log buffer archived which leads to system hungs.

    as log buffer is in memory, we will loose data if instance crashed. no roll forward information will be available to do crash recovery.

    stand by databases which are in high available and high protection mode need to find other methods.

    replication software like Oracle Golden Gate should be no longer real time because mining from archive log and apply SQL takes time.

    Just curious to know, how did you got this idea which needs to change Oracle architecture? did you see any advantages?

    Thanks,
    Vijay Tummala

    Try hard to get what you like OR you will be forced to like what you get.

  3. #3
    Join Date
    Jan 2001
    Posts
    2,828
    Hi

    This was a interview question.
    I wanted to hear from the experts my answer was incidentally similar to yours as oracle will batch writes and write to the logs and if there are no online logs then 100's of archived logs needs to be created depending on the transaction volume and performance maybe a hit

    I dont however agree with this statement

    as log buffer is in memory, we will loose data if instance crashed. no roll forward information will be available to do crash recovery.

    as the log buffer contains only changed data not commited ones

  4. #4
    Join Date
    Mar 2006
    Location
    Charlotte, NC
    Posts
    865
    I dont however agree with this statement

    as log buffer is in memory, we will loose data if instance crashed. no roll forward information will be available to do crash recovery.

    as the log buffer contains only changed data not committed ones

    agree with you hrishy. However, if there is no redo log concept, apparently Oracle has to maintain the committed records also in log buffer until flushed to archive log...

    Thanks,
    Vijay Tummala

    Try hard to get what you like OR you will be forced to like what you get.

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