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  1. #1
    Join Date
    Jul 2003
    Posts
    21

    Unanswered: Running Oracle EXP while the database is being accessed.

    Hi,

    I have a question to ask.

    Currently I am running a script that runs Oracle EXP to export the database tables in a specific interval.

    My que is , what could be the possible consequences if I run EXP while users are still accessing the database.

    I think as long as the users are reading the records, it won't be a problem.

    But as the users would update the database tables, depending upon the timing EXP might export the older records before updation by the user[s].

    Please let me know what could be the different scenarios according to u.

    Thanks,

    - Bikram.

  2. #2
    Join Date
    Jul 2003
    Location
    US
    Posts
    314

    Arrow Consequences

    Hi
    One thing that I know for sure, if your DB is large and your exporting most of the large tables, the response time to all the users would increase considerably.
    With regards to the updation of the data, I presume that exp would take all the data at the point it is exporting a particular table.
    Thanx and Regards
    Aruneesh

  3. #3
    Join Date
    Nov 2002
    Location
    Desk, slightly south of keyboard
    Posts
    697
    Exp is not guaranteed to give you a consistent dataset. Ie, you could have child keys in a table which via a constraint will fail on insert into another because they didn't exist when the master table was exported, but did exist when the child was.

    The only sure fire way of backing up an on-line database is, well, another story which is best left to the experts :-)

    To understand Oracle consistency do a google for "set transaction isolation level serializable". Bear in mind, that particular statement will almost always fail in a live updating environment - but it should point you in the right direction regarding consistency.

    Hth
    Bill

  4. #4
    Join Date
    Jul 2003
    Posts
    21
    Thanks a lot for your help.

    - Bikram.



    Originally posted by billm
    Exp is not guaranteed to give you a consistent dataset. Ie, you could have child keys in a table which via a constraint will fail on insert into another because they didn't exist when the master table was exported, but did exist when the child was.

    The only sure fire way of backing up an on-line database is, well, another story which is best left to the experts :-)

    To understand Oracle consistency do a google for "set transaction isolation level serializable". Bear in mind, that particular statement will almost always fail in a live updating environment - but it should point you in the right direction regarding consistency.

    Hth
    Bill

  5. #5
    Join Date
    Jul 2003
    Posts
    2,296
    I thought consistent=Y solves this issue.
    It doesn't?

    I run a refresh of production into another environment 3 times a day and my import never has any problems ...

    Bill, you are making me worry.
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  6. #6
    Join Date
    Nov 2002
    Location
    Desk, slightly south of keyboard
    Posts
    697
    Oops, yes, sorry you're quite right. It should give you a consistent dataset.

    I'm afraid I still have this quaint/quirky belief that the only consistent database is a stopped one. But for export, yes you're right.

    Anyone got a shovel.

    Cheers
    Bill

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