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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Tuning Large Pool
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,
-----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_at_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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