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  • 30. Re: Block Size
    108476 Journeyer
    Currently Being Moderated
    Hi Hans,

    I do not know this first-hand, but it was told to me by someone who had taken the Oracle University DBA intro classes. He said that there was a slide discussing how to choose your blocksize.

    My apologies if this is wrong . . . . .
  • 31. Re: Block Size
    311441 Employee ACE
    Currently Being Moderated
    Hi Don

    What does the oss.oracle.com link have to do with multiple Oracle database blocksizes ?

    Why do you keep referencing the KEEP and RECYCLE pools doco when discussing multiple blocksizes ?

    Where does the Oracle doco suggest performance benefits with multiple blocksizes ?

    Which Oracle class suggests performance benefits with multiple blocksizes ?

    Not everyone notes a "marginal benefit". Here's an example of performance being worse:

    http://richardfoote.files.wordpress.com/2008/03/small-scans-in-larger-block-tablespace.pdf

    Balkrishan Mittal on you're own consensus multiple blocksize link highlights how he had massive CPU problems with a larger block size and had to put it back down again after a few days:

    http://www.dba-oracle.com/t_multiple_blocksizes_summary.htm

    Finally, why is it you think "For most databases, creating multiple blocksizes is not going to make a measurable difference" ? When will it make a measureable difference ?

    Cheers

    Richard Foote
    http://richardfoote.wordpress.com/
  • 32. Re: Block Size
    26741 Oracle ACE
    Currently Being Moderated
    [not replying to Richard specifically only, but to the group]

    Since my earlier posting in this thread seems to have been "un-read", I am re-posting
    it here :

    Would large block sizes in a seperate tablespace make sense for LOBs only,
    eg if we use Out Of Line LOB Segments for LOBs (holding say, 100K or more
    of data per row), when the rest of the database uses the generic 8K block size ?

    {adding to the "100K" reference :}
    For a LOB that is stored Out Of Line, if the typical
    size is, say 32K or 64K, I might still stick to an 8K
    block size. If it is, say 1M, I might consider a 16K
    block size (or should I ?). If it is say, 100M, I
    would go for a 32K block size. But I would also,
    probably, define that large a LOB column as NOCACHE.
    ?? comments ?

    Even the repeated "case" of Transportable Tablespaces is too generalised.
    DataWarehouses, too, may be setup with 8K block sizes , the same as the OLTP
    databases they are built from. So we have the same block size and we can use
    Transportable Tablespaces IF we really have data that is tranported "as is" rather
    than extracted through other routines (PLSQL over DBLinks, ETL tools like
    DataStage etc).
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