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Home -> Community -> Mailing Lists -> Oracle-L -> Re: 2k and 8k block size
My question was specific to RAC: With a larger block size, is one not increasing the chances of pinging for the blocks? Or I dont need to worry about it with Cache fusion? A new worry for me now is that, though the block size was changed from 2K to 8K, the recommendation was to keep the SGA the same?
Anyways, I am still setting up the database, and I plan to create a few tables in tablespaces of varied block sizes, and test it myself. During stress testing, I expect to see a lot of waits.
A new question: All recommendations that I have read so far is to make the datablock block size equal to the file system block size? But what if my datafiles are raw disks?
Thanks
Raj
Charlie_Mengler_at_Hom
eDepot.com To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
Sent by: cc:
root_at_fatcity.com Subject: Re: 2k and 8k block size
February 14, 2003
11:09 AM
Please respond to
ORACLE-L
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
Please respond to
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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Please see the official ORACLE-L FAQ: http://www.orafaq.net
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Author:
INET: Rajesh.Rao_at_jpmchase.com
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