Message-ID: <F001.0054013F.20030130210902@fatcity.com>
Date: Thu, 30 Jan 2003 21:09:02 -0800
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From: "Deshpande, Kirti" <kirti.deshpande@verizon.com>
Subject: RE: Tuning Large Pool
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In 8i LARGE_POOL_SIZE defaulted to 18M if not set when using P_A_T. I have not yet tried this in 9i, though. 
But, if P_A_T is set to true, it affects a number of other parameters. 
Check Oracle9i Data Warehousing Guide. There is a chapter (#21) on Parallel Execution.
 
And there is a formula to compute LARGE_POOL_SIZE using PARALLEL_EXECUTION_POOL plus other geeky stuff... :) 

The catch is they don't explain how PARALLEL_EXECUTION_POOL is computed. Doesn't it sound like an init.ora parameter?

 but it is not). 

In one of the Metalink forum threads, there is a reference to review other related parameters as described in that chapter to establish resource limits for Parallel Operations. So, this is a new term manufactured by Oracle to keep us guessing. 
  
I would not set LARGE_POOL_SIZE to any value if I used P_A_T. Let Oracle figure it out. 
One can always check what values Oracle derives for other parameters... 

I don't think LARGE_POOL_SIZE will shrink once it gets allocated. Shrinking memory dynamically is an expensive operation. 

HTH,

- Kirti    

-----Original Message-----
Sent: Thursday, January 30, 2003 9:39 PM
To: Multiple recipients of list ORACLE-L


Tc - I haven't played with these parameters, so I can only offer some ideas
based on the documentation, and maybe someone who has tested this will
respond.
   It looks like if you set PARALLEL_AUTOMATIC_TUNING and leave the
LARGE_POOL_SIZE unset, then Oracle will calculate the large pool size for
you. Maybe Oracle thinks you have set LARGE_POOL_SIZE too low and it is
providing a higher value. One test you could perform would be to comment
LARGE_POOL_SIZE out and see if you receive the same value. 
   Now, as to Oracle dynamically reducing the LARGE_POOL_SIZE, I don't see
any hint that this will occur. Have you seen this mentioned somewhere?

Dennis Williams
DBA, 40%OCP
Lifetouch, Inc.
dwilliams@lifetouch.com 


-----Original Message-----
Sent: Thursday, January 30, 2003 8:22 PM
To: Multiple recipients of list ORACLE-L


Dennis,
	Its 9i release 9.0.1.1.1 on Windows 2000.
Heres the query & output

SQL> select name,round(bytes/(1024*1024),1) from v$sgastat where pool='large
pool';
Enter ...

NAME                       ROUND(BYTES/(1024*1024),1)
-------------------------- --------------------------
free memory                                    4095.9
PX msg pool                                        .1

Elapsed: 00:00:00.07
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Author: Deshpande, Kirti
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