ryan.gaffuri_at_cox.net wrote:
>
> One of our production DBAs does not want to use pga_aggregate_target on a 9.2.0.3 instance due to a possible memory leak. The only note on memory leaks and pga_aggregate_target I can find on metalink is: 334427.995
>
> doesnt seem to apply to pga_aggregate_target. We are on sun solaris. Dont know version offhand.
>
> he is under the impression that if we patch to 9.2.0.4 this goes away. not sure about that either...
>
Be careful with pga_aggregate_target. I have very recently seen a case
(Solaris + 9.2 but I cant't tell you exactly which patch level -
probably the most recent) where two (by the way atrocious) queries
generated by a DSS tool were responding very differently - and in a way
that differences in the queries couldn't explain. From an Oracle
standpoint, stats were roughly the same. Tracing proved that we were
waiting for CPU, and truss that a call to mmap() was the culprit. Why,
no idea. We first switched it (pga_thing) off, no more slow call to
mmap(). However, it was still slow because we hadn't checked
sort_area_size which was ridiculously small. We set sort_area_size to
10M, still with pga_aggregate_target unset, and once again the same very
slow calls to mmap(). Memory misalignment? Anything else? Not much time
to enquire but it looks like a mine field.
--
Regards,
Stephane Faroult
Oriole Software
--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Stephane Faroult
INET: sfaroult_at_oriole.com
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Received on Tue Jan 20 2004 - 13:59:27 CST
