Re: shared pool subpool
- From: K Gopalakrishnan <kaygopal@xxxxxxxxx>
- To: eagle.f@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
- Date: Mon, 23 Oct 2006 22:10:14 -0700 (PDT)
Without knowing more details about your application it would be difficult for
us to come to a conclusion. However to answer your question, the memory
management of shared(sub) pools is similar to shared pool with LRU lists and
reserved lists.
To workaround this issue, you may want to reduce the number of subpools by
setting _kghdsidix_count parameter. We have a short discussion about inner
workings of shared (sub) pools in our OWI book. Search in metalink for the
above parameter and you may (!) hit some bugs for your version.:)
Good Luck !
Have a nice day !!
------------------------------------------------------------
Best Regards,
K Gopalakrishnan,
Co-Author: Oracle Wait Interface: Oracle Press 2004.
http://www.amazon.com/gp/product/007222729X/
Author: Oracle Database 10g RAC Handbook, Oracle Press 2006
http://www.amazon.com/gp/product/007146509X/
----- Original Message ----
From: eagle fan <eagle.f@xxxxxxxxx>
To: oracle-l@xxxxxxxxxxxxx
Sent: Monday, 23 October, 2006 9:26:55 PM
Subject: shared pool subpool
hi:
My database version is 9.2.0.5. The share pool still has 115M free memory.
POOL NAME BYTES
----------- -------------------------- ----------------
shared pool free memory 115,596,712
But from x$ksmss, the free memory of one subpool only has 5M
SQL> select * from x$ksmss where ksmssnam='free memory';
ADDR INDX INST_ID KSMSSLEN KSMSSNAM
KSMDSIDX
---------------- ---------- ---------- ---------- --------------------------
----------
000000010382A6D0 0 1 5190392 free memory
1
000000010382A6D0 38 1 49780448 free memory
2
000000010382A6D0 76 1 38853392 free memory
3
000000010382A6D0 114 1 21255952 free memory
4
And this subpool contiguously flush out chunks and caused a lot of hard
parses(from x$kghlu).
RECURRENT TRANSIENT FLUSHED PINS AND ORA-4031 LAST ERROR
KGHLUIDX CHUNKS CHUNKS CHUNKS RELEASES ERRORS SIZE
---------- ---------- ---------- ---------- ---------- ---------- ----------
4 1404 1658 27895 627992485 0 0
3 1064 1866 21377 69010651 0 0
2 1384 1887 20373 81774898 0 0
1 1248 2536 1355842 437478666 5558 27224
Why the sql goes to the subpool which has very less free memory. What's the
algorithm of subpool space management?
We have same experiences on many cases before, the only thing what we can do is
set shared_pool_size to a bigger value and bounce the database.
I tried to search internet for more shared pool internal infomation, but only
found very limited metarials.
Any ideas or metarials are appriciated.
--
Eagle Fan
Oracle DBA
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