Re: Partitionining perfortmance degraded drastically after upgrading the database from Oracle 102.0.4 to Oracle 11.2.0.3
- From: Ls Cheng <exriscer@xxxxxxxxx>
- To: ashoke.k.mandal@xxxxxxxxxxxxx
- Date: Sat, 10 Jan 2015 01:21:04 +0100
I always have a doubt, why people set SGA_TARGET smaller than SGA_MAX_SIZE.
What is the objective of doing so?
Regarding your issues, as many already pointed out you have cut your memory
assignment to half, that is first thing to look at. The second is obviously
the execution plans. Are the statistics refreshed in 11.2? Can you provide
a couple of AWR in 10g and in 11g so we can compare?
Thanks
On Fri, Jan 9, 2015 at 7:02 PM, Mandal, Ashoke <
ashoke.k.mandal@xxxxxxxxxxxxx> wrote:
> Hello Mark, Originally PGA_AGGREGATE_TARGET value of 6GB was too high.
> I meant to use total memory(MEMORY_TARGET) of 6GB to manage everything.
>
> Leaving SGA_MAX_SIZE=1G was a typo error. I wanted to set this to 0 so
> that Oracle allocate as needed basis. There is also another thing about
> this upgraded database. We haven’t changed the compatible parameter to to
> 11.2.0 yet and it is still at 10.2.0.
>
>
>
> Do you see any negative impact due to the compatible setting as 10.20.0
> for the 11g database?
>
>
>
> I will set the SGA_MAX_SIZE to 0 and the compatible to ’11.2.0’ and bounce
> the database and see if that helps the performance.
>
>
>
> Thanks,
>
> Ashoke
>
>
>
> *From:* MARK BRINSMEAD [mailto:mark.brinsmead@xxxxxxxxx]
> *Sent:* Friday, January 09, 2015 11:20 AM
> *To:* Mandal, Ashoke
> *Cc:* oracle-l-bounce@xxxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
> *Subject:* Re: Partitionining perfortmance degraded drastically after
> upgrading the database from Oracle 102.0.4 to Oracle 11.2.0.3
>
>
>
> It rather looks like you have cut your SGA from 6 GB (which may already
> have been rather lean) to 1GB, and reduced the total available memory from
> 12 GB to 6GB.
>
> Why are you surprised that this affects performance? I doubt the problem
> you are encountering has anything to do with Partitioning. There is
> probably almost NO memory available for buffer cache, and quite likely too
> little for the shared pool, too. The (more modest) reduction in memory
> available for the PGA may affect execution plans by causing a bias from
> HASH joins toward NESTED LOOPS.
>
> Commonly, people choose (need) to *increase* the memory available to the
> SGA when upgrading. At the very least, they will keep memory unchanged.
> Slashing the memory footprint in half is an uncommon move during an
> upgrade, and one that you will probably want to rethink.
>
> If you want more help here, let's start with some DATA. Something like
> the "Top-5 Waits" for pre- and post-upgrade might be a good place to
> start. After that, perhaps execution plans and wait information for the
> (most) affected queries. Without this, people here can only guess at the
> actual cause of your problem, although if enough of us guess for a long
> enough time, somebody will undoubtedly find the right answer eventually.
> (My money is on the changes to memory; I suggest we eliminate THAT as a
> cause before we move on to other possibilities, since we KNOW that was
> changed.)
>
>
>
> On Fri, Jan 9, 2015 at 8:58 AM, Mandal, Ashoke <
> ashoke.k.mandal@xxxxxxxxxxxxx> wrote:
>
> Greetings All,
>
> I have upgraded one of my 2TB databases with partitioned tables & indexes
> from Oracle 10.2.0.4 to Oracle 11.2.0.3 recently and experiencing severe
> poor query performance. The response time of the queries have increased by
> 20-25 times.
>
> Before the upgrade to 11g
> PGA_AGGREGATE_TARGET=6GB
> SGA_TARGET=4GB
> SGA_MAX_SIZE=6GB
>
> After the upgrade to 11g
> MEMORY_TARGET=6GB
> PGA_AGGREGATE_TARGET=0
> SGA_TARGET=0
> SGA_MAX_SIZE=1GB
>
> My understanding is that if I set SGA_TARGET and PGA_AGGREGATE_TARGET
> parameters to 0 then Oracle manages theses as per the MEMORY_TARGET
> parameter in 11g.
> Q. Is it true that the SGA can't grow more than 1GB since SGA_MAX_SIZE is
> still set to 1GB?
> Q2. Will the performance improve by setting SGA_TARGET to 4GB by default?
> Q3. Should I also set the PGA_AGGREGATE_TARGET to GB as it was prior the
> upgrade?
> Q4. Any known issue of partitioning performance impact after you upgrade a
> 10g database to 11g?
>
> Please let me know if you any suggestions to resolve this issue
>
> Appreciate your help in advance,
> Ashoke
>
>
> [CONFIDENTIALITY AND PRIVACY NOTICE]
>
> Information transmitted by this email is proprietary to Medtronic and is
> intended for use only by the individual or entity to which it is addressed,
> and may contain information that is private, privileged, confidential or
> exempt from disclosure under applicable law. If you are not the intended
> recipient or it appears that this mail has been forwarded to you without
> proper authority, you are notified that any use or dissemination of this
> information in any manner is strictly prohibited. In such cases, please
> delete this mail from your records.
>
> To view this notice in other languages you can either select the following
> link or manually copy and paste the link into the address bar of a web
> browser: http://emaildisclaimer.medtronic.com
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
Other related posts:
