export dump
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Thread: export dump

  1. #1
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    export dump

    when we take a export dump with compress =y option, how does one get to know that the actual compression has taken place?

    Sharmila
    -----------
    OCP 8i

  2. #2
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    When you export to dump file with compress=y, EXPORT utility modifies the INITIAL value of the table to be the sum of the current extents. So that means if the table has 50 * 10K extents filled, then the INITIAL extent when you IMPORT the data will be 500K.
    Agasimani
    OCP(10g/9i/8i/8)

  3. #3
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    thanks , i very well know that this is what happens, but what i was wondering is that how do one come to know that such a option is used,, any query , DD views to tell us that compress =y has taken effect

    Sharmila
    -----------
    OCP 8i

  4. #4
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    .
    Last edited by bang_dba; 12-18-2002 at 06:37 AM.

  5. #5
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    check dba_extents.bytes and compare with the older value.

    By default compress=y
    if u want to retain the old storage values say compress=no

  6. #6
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    compress=y is a no no option

  7. #7
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    Originally posted by sharmila
    ... but what i was wondering is that how do one come to know that such a option is used,, any query , DD views to tell us that compress =y has taken effect
    AFAIK there is no DD views for this.
    Giani

  8. #8
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    Originally posted by pando
    compress=y is a no no option
    pando, please explain - tx
    "The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman

  9. #9
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    Originally posted by DaPi
    pando, please explain - tx
    Oooh oooh! I know this one!

    compress=y leads to tablespace fragmentation by having different sized extents created on import.
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  10. #10
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    if you understand well delete, truncate, segments and extents you will see why

    if I have 100 extents with 1MB each but there are only 1MB real data what happens if I export with compress=y? I will get one 100MB extent 99% empty, if I use compress=n what happens? I get 1extent of 1MB, I saved 99MB

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