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datablock sizing

P: n/a
Hi All,

Thank you for your feedback on # of tablespaces. Can anyone share some
experiences on sizing the data block ?.

Assuming that the biggest row I would have takes up about 2K, what
should be the size of data block? I am debating between 8K and 16K. Is
there a rule of thumb as to how many rows should fit in a data block?.

Thanks a lot in advance,

Vissu
Jul 19 '05 #1
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vi*****@yahoo.com (Vissu) wrote in message news:<2b**************************@posting.google. com>...
Hi All,

Thank you for your feedback on # of tablespaces. Can anyone share some
experiences on sizing the data block ?.

Assuming that the biggest row I would have takes up about 2K, what
should be the size of data block? I am debating between 8K and 16K. Is
there a rule of thumb as to how many rows should fit in a data block?.

Thanks a lot in advance,

Vissu


It really depends on the nature of your application. Oracle will
always read a block, even if you need a single row. Consequently if
you run an OLTP app and your blocksize is 16k, and you retrieve only 1
row, you waste 14k (according to your figures). If 8k you only waste
6k. If you have a warehouse app, 16k might help you.
In 9i you can have tablespaces with different blocksizes.

Sybrand Bakker
Senior Oracle DBA
Jul 19 '05 #2

P: n/a
vi*****@yahoo.com (Vissu) wrote in message news:<2b**************************@posting.google. com>...
Hi All,

Thank you for your feedback on # of tablespaces. Can anyone share some
experiences on sizing the data block ?.

Assuming that the biggest row I would have takes up about 2K, what
should be the size of data block? I am debating between 8K and 16K. Is
there a rule of thumb as to how many rows should fit in a data block?.

Thanks a lot in advance,

Vissu


What kind of application does the database have to support: OLTP, DSS,
OLAP, etc ...?

The answer depends of what type of processing is most common, most
critical etc.... I am in favor of using multiple block sizes in one
database. To do so means you must manage multiple buffer pools and
you can easily end up with the condition that during specific
processing periods you need the memory dedicated to 4K blocks in the
16K block pool but the 16K block pool is under utilized 85% of the
time so the space would be better allocated to the 8K pool.

HTH -- Mark D Powell --
Jul 19 '05 #3

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