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Thread: export problem

  1. #1
    Join Date
    Jun 2003
    Posts
    24

    Question export problem

    Hi,

    Need to ask concerning export. How will u able to export a table that is constantly being updated coz I am facing ora-01555 snapshot to old when I do an export for a particular table though the smallest rollback segment is 400M. Does anyone has any idea.

  2. #2
    Join Date
    Oct 2000
    Posts
    467

    Re: export problem

    Originally posted by cindynwl
    Hi,

    I do an export for a particular table though the smallest rollback segment is 400M. Does anyone has any idea.

    Export does not use RBS, except to get the consistent data for the table. Try increasing the RBS size overall or run the export when the updates on the table are less and data is more consistent.
    BTW, what r ur RBS optimal/min_extents parameters ?
    Vinit

  3. #3
    Join Date
    Jun 2003
    Posts
    24
    Hi,

    I have created many rollback segment with at least 1G space or more but then I still get the same error.The table has more than 5 million rows and there are active trnsaction. I am not able to set it into restricted mode coz it is a 24*7 database. is there other way besides way besides setting it in restricted session.

    here are the breakdown of rollback segments
    SEGMENT_NAME OWNER TABLESPACE_NAME INITIAL_EX
    MIN_EXTENT STATUS
    ------------------------------ ------ ------------------------------ ----------
    ---------- ----------------
    SYSTEM SYS SYSTEM 57344
    2 ONLINE
    RB6 PUBLIC RB 838860800
    2 ONLINE
    ROLLBACK8 PUBLIC ROLLBACK 524288000
    2 ONLINE
    ROLLBACK9 PUBLIC ROLLBACK 524288000
    2 ONLINE
    ROLLBACK10 PUBLIC ROLLBACK 419430400
    2 ONLINE

  4. #4
    Join Date
    Dec 2000
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    Ljubljana, Slovenia
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    If you can afford it and if it's applicable for your system, you could transform your big table into partitioned table. Smaller partitions are much less prone to ORA-1555 during export, you'll have much better chances to perform export on that big partitioned table without being hit by "snapshot too old".

    Of course this is only one of the "managebility aspects" of using partitioning, you'll have to consider the benefits and pitfalls of all other aspects (performance, managebility, cost) in relation to your system before jumping into partitioning.
    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

  5. #5
    Join Date
    Jun 2003
    Posts
    24
    Hi,
    Just want to ask further....does it really make a diferrence when the table is being partitioned when doing an export coz it will still be accesing the full table rite...
    correct me if I am wrong

    Cindy

  6. #6
    Join Date
    Dec 2000
    Location
    Ljubljana, Slovenia
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    4,439
    During export (with CONSISTENT=N, which is default), the unit of work that has to be exported in consistent mode is the segment. With nonpartitioned table this simply means the whole table, while on partitioned table this is a single partition.

    So when exporting a partitioned table, it is virtualy the same as you would be exporting many smaller tables. Each partition will be exported in a consistent mode by itself, yet all the partitions might not be exported consistently in relation to each other.
    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

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