Oracle-L: Re: db_file_multiblock_read

From: Tim Gorman <tim_at_sagelogix.com>
Date: Sat, 13 Sep 2003 12:59:24 -0800
Message-ID: <F001.005CFD28.20030913125924@fatcity.com>

I've performed "nm -o oracle" and "strings -a oracle" on the Oracle executable, searching for the phrase "sstiomax" to no avail. To me, that implies that SSTIOMAX is not a variable in the "C" program that is Oracle. Instead, by C programmer conventions, any name expressed in all upper-case would most likely be a "#define" constant and not a variable, which is impossible to display without source code or the ability to read object code. Without source code access, of course, this is just a guess, as conventions can be ignored.

You can likely deduce SSTIOMAX by setting DBFMBRC to some insanely high value then performing a FULL table scan under SQL trace level-8 as specified in "http://www.oracledba.co.uk/tips/mbrc.htm".

Of course, this web page was found by searching Google using the search phrase "sstiomax"...

on 9/13/03 1:04 PM, Ravi Kulkarni at nandagokul_at_yahoo.com wrote:

> How can we find the value of SSTIOMAX ?(What is it for
> 9i ?)
> 
> Thanks,
> Ravi.
> --- Tim Gorman <tim_at_sagelogix.com> wrote:

>> There is a MetaLink article #131530.1 on the
>> constant SSTIOMAX which may
>> provide some interesting reading on this topic
>> surround "max I/O size" and
>> the setting of DBFMRC. The article is over 2 years
>> old -- not sure if it
>> pertains to 9i or above...
>>
>> Wolfgang, please let us know how those 8-byte
>> database blocks work for you,
>> OK?
>>
>>
>>
>> on 9/11/03 8:44 PM, Wolfgang Breitling at
>> breitliw_at_centrexcc.com wrote:
>>

>>> db_block_size=8, db_file_multiblock_read_count =

>> 32

>>> 
>>> That is a Peoplesoft ERP system, a hybrid of oltp

>> and dss with heavy

>>> reporting activity at month end. The dfmrc value

>> was established through

>>> trial and 10053 trace analysis. Some report sql

>> still require use_hash

>>> hints in order to avoid silly NL joins. Was

>> looking forward to upgrading to

>>> Oracle 9 with system statistics so that I could

>> jack up dfmrc to the max

>>> without nasty side-effect for the oltp part, but

>> I'm essentially out of

>>> that account now.
>>> 
>>> As for finding the max operating system I/O size

>> on windows (or any other),

>>> just set dfmrc to some insanely high number and

>> let Oracle figure out what

>>> the OS wil bear.
>>> 
>>> At 01:59 PM 9/11/2003 -0800, you wrote:
>>>> Hello list, seeking your personal opinions and

>> experiences about

>>>> db_file_multiblock_read_count.
>>>> 
>>>> What do you all set your db_block_size and

>> db_file_multiblock_read_count

>>>> to?
>>>> 
>>>> How did  you all come to decide that  those

>> values would suit your systems ?

>>>> 
>>>> Any windoze user here who can tell me how can one

>> find out the max operating

>>>> system I/O size (on windows) in order to set

>> db_file_multiblock_read_count ?

>>> 
>>> Wolfgang Breitling
>>> Oracle7, 8, 8i, 9i OCP DBA
>>> Centrex Consulting Corporation
>>> http://www.centrexcc.com
>>>

>>
>> --
>> Please see the official ORACLE-L FAQ:
>> http://www.orafaq.net
>> --
>> Author: Tim Gorman
>> INET: tim_at_sagelogix.com
>>
>> Fat City Network Services -- 858-538-5051
>> http://www.fatcity.com
>> San Diego, California -- Mailing list and web
>> hosting services
>>

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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Tim Gorman
  INET: tim_at_sagelogix.com

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Received on Sat Sep 13 2003 - 15:59:24 CDT

Re: db_file_multiblock_read_count