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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Performance Problem after Migration
I have done this before and I always do it
on a test machine first as everything that
has been tuned up to this point is now at step
1 all over again.
Did you import everything properly ? Indexes ?
Make sure your schema objects are analyzed again.
Find out the time of the day where the real slowdown
occurs and you should be able to pinpoint the "BAD" sql
and tune it.
Use the system and session wait interface. Also,
during that time set up your 10046 event 12 data
and look for your main waits. Goto to the developer/user
that is complaining the most and try to feel their pain by running
through the application yourself and gathering the
stats at the time the application is running.
Also, I would buy Gaja and Kirti's book Oracle
Performance Tuning 101 which is dedicated to this
type of troubleshooting. Also, see
www.hotsos.com for 10046 information and Cary
is very good at explaining things.
Consider getting some logs on these waits and posting them here as there are many folks who are on this board that are very smart in these areas.
PS.. Once you start doing this stuff and get used to it, it gets easier and easier.
Good Luck to you !
FWIW ...Mike
-----Original Message-----
Sent: Thursday, August 01, 2002 2:28 PM
To: Multiple recipients of list ORACLE-L
I have an interesting problem. I recently migrated a database from a Digital Unix system to a Sun Solaris system, with an EMC disk array. Since I was going to be migrating the database, I decided to double the block size from 4k to 8k. I also created the tablespaces on the new box as locally managed, with fixed extent sizes. Then I did a full database export, ftp'd the file, and imported it. It went well, or so I thought. The application works, but it is much slower than it was on the original (Digital) system.
One side effect was that I didn't change the db_block_buffers, so that part of the SGA essentially doubled in size. The library cache hit rate was always around 99%, but the data cache hit rate used to only be about 85%, now it is 95 - 99%. All of the sorts are being done in memory, with memory to spare (52G yesterday, not used). According to the statistics, the database should be screaming. But the users are complaining that the online screens are taking much longer to come up. They say that the screens used to come up in 1 - 2 seconds, now it's taking about 10.
Just for fun, I tried deleting the statistics and changing the optimizer_mode from choose to rule. That made things worse, which was what I expected, but it was worth a try. I have tried to capture a session, but I need to get a repository up to look at the trace that was generated. Until then, I'm pretty baffled. I'd appreciate any ideas that anyone has on this.
Thank you.
--
Scott Canaan (srcdco_at_rit.edu)
(585) 475-7886
"Life is like a sewer, what you get out of it depends on what you put
into it" - Tom Lehrer
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Please see the official ORACLE-L FAQ: http://www.orafaq.com
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Author: Scott Canaan
INET: srcdco_at_ritvax.rit.edu
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Liststo: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
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