There is also a Horrible bug along these lines that actually causes
queries to occasionally yield incorrect results.https://metalink.oracle.com/metalink/plsql/f?p=130:4:4310688952095264987
which is avoided by set "_gby_hash_aggregation_enabled" to FALSE.
On Behalf Of Limin Guo
Sent: Tuesday, June 12, 2007 11:27 AM
Cc: Peter McLarty; oracle-l_at_freelists.org
Subject: Re: 10g vs 9i
I had similar problem when upgrading application from 22.214.171.124 to
10.2.0.2 last year. I discovered my problem was caused the bug 5095456
in 10.2.0.2. Oracle's workaround for the bug is to set the following
Try them first and see how your query reacts.
Hope this helps,
On 6/12/07, Ujang Jaenudin wrote:
for the oltp users, they didn't give me an alert.
but i'm testing a report as exactly so many joins, even the latest
result comes from the result set not from table directly,,,, something
select * from (select .... from a,b where ... ( select .....))....
tested on 9i it tooks only 30min, but on 10g rac, till 2hours and never
could you point me which v$ ?
On 6/12/07, Peter McLarty wrote:
I have seen this behaviour. It happens going from 9 to 10 at any level.
In the case I had was due to things doing joins whose performance
changed due to the effects of the optimiser.
You will have to take each case by itself and analyse it. I would
consult with your business users for their worst performer and isolate
the cause of that and then work back from there removing the most
It is likely as you take it apart you may fix a number of issues at the
Look out for joins to v$ views as these performed badly
From: Ujang Jaenudin
Sent: Tuesday, 12 June 2007 03:14 PM
Subject: 10g vs 9i
recently i have a dev machine 10g on itanium ia-64 another linux is
itanium ia-64 with 9i
the performance on 10g (10.2.0.3) is dropped for almost 1/3 from the 9i,
if someone has the same experiences, pls share....
all these parameters doesn't help either...
alter system set optimizer_features_enable='9.2.0' scope=both; alter
system set "_optimizer_cost_based_transformation" =on scope=both; alter
system set "_gby_hash_aggregation_enabled" = TRUE scope=both;
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