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  1. #1
    Join Date
    Aug 2002
    Location
    Shanghai , China
    Posts
    63

    Unanswered: How the data is imported?

    UserA's default tablespace is TAB1 which consists of 5 datafiles (DF1~DF2)
    I created DF1 first , then DF2 onwards.

    When I import the data into this UserA . I found DF4 is got data first . I seems there is no relation which datafile I create first .

    Any gurus knows about it?
    Oracle is an ocean . I am just a little fish

  2. #2
    Join Date
    Oct 2002
    Location
    greenwich.ct.us
    Posts
    279
    You're right, there is no relation as to which datafile will be chosen first.

  3. #3
    Join Date
    Apr 2002
    Location
    California, USA
    Posts
    482

    Cool

    If you look at the export dump file, you will see that only the INSERT ... statements have the tables and indexes ordered. Which datafile to use of the tablespace is completely random.


    Hope that helps,

    clio_usa
    OCP - DBA

  4. #4
    Join Date
    Oct 2002
    Location
    greenwich.ct.us
    Posts
    279

  5. #5
    Join Date
    Apr 2002
    Location
    California, USA
    Posts
    482

    Cool

    Yeah, right. I was looking for something in my defense. It's right under the provided link:

    Allocating Extents in Locally-Managed Tablespaces
    In locally-managed tablespaces, Oracle looks for free space to allocate to a new extent by first determining a candidate datafile in the tablespace and then searching the datafile's bitmap for the required number of adjacent free blocks. If that datafile does not have enough adjacent free space, Oracle looks in another datafile.
    There is no way for Oracle to search in ordered fashion. It goes from datafile to datafile until finds the free space. And if DBA adds more datafiles the whole order will be changed since will allocate extents first in the newly created datafiles.

    Am I missing something???

    Hope that helps,

    clio_usa
    OCP - DBA

  6. #6
    Join Date
    Oct 2002
    Location
    greenwich.ct.us
    Posts
    279
    Ah,
    Oracle looks for free space to allocate to a new extent by first determining a candidate datafile in the tablespace and then searching the datafile's bitmap for the required number of adjacent free blocks. If that datafile does not have enough adjacent free space, Oracle looks in another datafile.
    is a little different than "completely random"...

  7. #7
    Join Date
    Apr 2002
    Location
    California, USA
    Posts
    482

    Cool

    OK.

    Change in the wording - "Oracle is choosing a datafile using a managed random algorithm". How that does look like??


    Hope that helps,

    clio_usa
    OCP - DBA

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