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Re: 2k and 8k block size

From: <Charlie_Mengler_at_HomeDepot.com>
Date: Fri, 14 Feb 2003 08:09:18 -0800
Message-ID: <F001.0054DB61.20030214080918@fatcity.com>

There was a presentation at the recent HOTSOS conference which showed a performance gain by placing indexes in tablespaces with a "LARGE" blocksize.

HTH & YMMV HAND!

                                                                                                                                 
                      Michael Fontana                                                                                            
                      <mfontana_at_verio.n        To:       Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>             
                      et>                      cc:                                                                               
                      Sent by:                 Subject:  Re: 2k and  8k block size                                               
                      root_at_fatcity.com                                                                                           
                                                                                                                                 
                                                                                                                                 
                      02/10/2003 01:59                                                                                           
                      PM                                                                                                         
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                      ORACLE-L                                                                                                   
                                                                                                                                 
                                                                                                                                 




Reading my oracle 9i new features , there is now something called: Multiple Database Block Size Support. In other words, it is no longer necessary
to commit to a single block size for your database. I'd suggest looking into this, as
it may now be possible to test using different blocksizes for different tablespaces.

At 01:04 PM 2/10/2003 -0800, Rajesh.Rao_at_jpmchase.com wrote:

      An 8.0.6 ops database being migrated to 9i RAC database on Solaris 8.
      The
      8.0 database had an block size of 2k.  Multiblock read count is 8.
      This is
      an OLTP database, all transactions almost always work on a single
      row. None
      of the row sizes exceed the block size. Hardly any chained or
      migrated
      rows. Now, during this migration, it was recommended to change the
      block
      size to 8k. And my concerns are:

      1. Would this not increase pinging across the instances? With 9i and
      interconnect and cache fusion, this should be reduced considerably,
      so, is
      it a mute point?
      2. This could alter the execution plans of some statements. Would
      some,
      maybe a very few of the statements not prefer a full table scan?

      Any other positive or negative effects of this increase in block
      size?

      Thanks
      One Paranoid DBA



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Author:
  INET: Charlie_Mengler_at_HomeDepot.com

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