db_block_size
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Thread: db_block_size

  1. #1
    Join Date
    Sep 2001
    Location
    chennai
    Posts
    69
    i am a new DBA. how to arrive at the block size( ie 2k or 4k or 8k or 16k).
    what factor(s) is/are used to deceid this block size. can anyone help me out to find
    this.

  2. #2
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
    Posts
    3,938
    Somebody may lecture on this for hours. The healine is: use 8K if you do not run DSS in which case 16K.


  3. #3
    Join Date
    Aug 2001
    Location
    Waterloo, On
    Posts
    547
    1. Type of application
    If DSS: Large block size: 16/32
    If OLTP: Small 4/8
    If Hybrid: Compromise.

    2. Type of data
    If many rows of LOBs type data, bigger block size would be required to hold the rows so that chaining does'nt occur.

    3. Hard disks and other system resorces available.

    4. Many other considerations, I suppose.

    Raminder Singh

    Oracle Certified DBA: Oracle 8i, 9i


    Mail me at raminderahluwalia@rediffmail.com.

  4. #4
    Join Date
    Sep 2001
    Posts
    112
    My block size is 2K.

    If I want to change it I will need to recreate the whole database.

    Make sure you do your research and get the correct block size before you create the database. Doing this now will save you time and effort, always .

    Deciding where to put tablespaces and what the default storage parameters might be is useful b4 DB creation as well.

  5. #5
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
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    3,938
    My block size is 2K.
    In DBVERIFY you don't have to specify your block size, wasn't the default 2K :-)


  6. #6
    Join Date
    Sep 2001
    Posts
    112
    Yeah yeah, but it was already 2K when I arrived and they dont want me to 'fix' it .

  7. #7
    Join Date
    May 2000
    Location
    ATLANTA, GA, USA
    Posts
    3,135
    Go for 32K block size if your system supports even if the system is OLTP. There are a number of benefits having a bigger db_block_size.
    1 More Rows will be stored in a block.
    2 Reduction in I/O
    3 Free space for update is reduced.
    4 Elimination of free list contention.


  8. #8
    Join Date
    Sep 2001
    Posts
    112
    So you guys definetly think I should convince this company to increase the block size to 8K?

  9. #9
    Join Date
    Jun 2000
    Location
    Madrid, Spain
    Posts
    7,447
    migrate to 9i and you can have your multiple db block sizes

  10. #10
    Join Date
    Aug 2001
    Location
    Waterloo, On
    Posts
    547
    Originally posted by tamilselvan
    Go for 32K block size if your system supports even if the system is OLTP

    Would'nt block contention increase if too many users want to update rows in the same data block in OLTP?

    Also, kindly see the post of another moderator in:
    http://www.dbasupport.com/forums/sho...threadid=16232



    [Edited by Raminder on 09-29-2001 at 11:31 PM]

    Raminder Singh

    Oracle Certified DBA: Oracle 8i, 9i


    Mail me at raminderahluwalia@rediffmail.com.

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