New 10g Tablespace Sizing
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Thread: New 10g Tablespace Sizing

  1. #1
    Join Date
    Nov 2000
    Posts
    172

    New 10g Tablespace Sizing

    Hi all,

    I am migrating from 8i to 10g. I need to get the most out of the space in each datafile. I know space is cheap. But, we are paying someone to host the storage for us and do want to waste any space, it is expensive.

    Let starts with a small example:

    CREATE TABLESPACE lmtsmall DATAFILE '/u02/oracle/data/lmtsmall01.dbf' SIZE 5120k
    EXTENT MANAGEMENT LOCAL UNIFORM SIZE 128k
    SEGMENT SPACE MANAGEMENT AUTO;

    How much space do I need to add for the extent bitmap, so I use all the space in the file? Right now I should get 40 extents, but what about the bitmap?

    Thanks,
    Kathy

  2. #2
    Join Date
    Aug 2002
    Location
    Colorado Springs
    Posts
    5,253
    64kb, i believe. I think it's documented somewhere. Create a TS and check the free space.
    David Aldridge,
    "The Oracle Sponge"

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

    Oracle ACE

  3. #3
    Join Date
    Nov 2000
    Posts
    172
    Yes, I agree it was 64kb. I'm not sure now, though because I will be using the bitmap and not the header space.

    Here is from the docs. But, doesn't say how much space for bitmap?

    "Note:
    When you allocate a datafile for a locally managed tablespace, you should allow space for metadata used for space management (the extent bitmap or space header segment) which are part of user space. For example, if specify the UNIFORM clause in the extent management clause but you omit the SIZE parameter, then the default extent size is 1MB. In that case, the size specified for the datafile must be larger (at least one block plus space for the bitmap) than 1MB."

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