RE: Large PGA for a data warehouse on Windows 2003 advancedserver(32 bit)

  • From: "Ken Naim" <kennaim@xxxxxxxxx>
  • To: <JBECKSTROM@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>, <Brandon.Allen@xxxxxxxxxxx>
  • Date: Thu, 28 Jul 2005 12:01:59 -0500

Yes, that is the exact problem. 
 
 4096mb usable ram
-2048mb windows
-1024mb default windows setting for indirect_db_block_buffer
- 512mb sga
------
512mb/ 20 (to 30) concurrent users = 15-25mb/user. 
 
28gb of db block buffers just sitting there waiting to be processed.
 
Doesn't leave a lot of space for sorting and hash joins of gig's worth of
data. Even reducing the windows setting to 512mb doesn't add much
(30-50mb/user) especially considering how ram is essentially idle.
 
Ken.
 

  _____  

From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Jeffrey Beckstrom
Sent: Thursday, July 28, 2005 11:42 AM
To: oracle-l@xxxxxxxxxxxxx; kennaim@xxxxxxxxx; Brandon.Allen@xxxxxxxxxxx
Subject: RE: Large PGA for a data warehouse on Windows 2003
advancedserver(32 bit)


Don't forget to account for at least 500M for the buffer window used to map
the indirect buffers.

>>> "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx> 7/28/05 12:27:11 PM >>>

Ken,

See Metalink Note 1036312.6 for info on how to use up to 3GB (set /3GB
switch in your boot.ini) or see note 46001.1 for info on how to use more
than 3GB  (for buffer cache only - you have to set
USE_INDIRECT_DATA_BUFFERS=true, and then use the old, static
db_block_buffers instead of new, dynamic db_cache_size - and can't use
db_cache_advice either).  So, theoretically, I believe you could use 1GB for
Windows, 3GB for your PGA/SGA and then use the remaining 28GB for your
buffer cache.  I don't think there is anyway to allocate 4-6gb for PGA on
Windows, but maybe someone else will have an idea.  Have you opened a TAR?

I've used the 3GB switch a few times with no problems, but have never used
the second method for accessing > 3GB. If you try it, please let me know how
it goes.

Thanks,
Brandon

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On
Behalf Of Ken Naim
Sent: Thursday, July 28, 2005 9:15 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Large PGA for a data warehouse on Windows 2003 advanced server(32
bit)


Dear List,

I am developing a data warehouse using Oracle 10g R1 on Windows 2003
advanced server(32 bit). The server has 32gb of ram and ideally I'd like to
allocate a good portion of it to the pga and not just db block buffers. As I
understand it windows "sees" 4gb of ram, 2gb of which is for windows, 1gb
which is used for db block buffers which can map to higher regions of memory
for larger amounts of db block buffers, leaving only 1gb of memory for the
sga and pga. I'd like to know if there is a way to use more of the ram for
the pga, in the neighborhood of 4-6gb. 

My background is on the unix side, so please keep the switch to linux
comments to a minimum. I do not have a choice in this matter.

Thanks,

Ken Naim

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