Oracle Pros say Silver Bullets make jobs run
faster
October 18, 2005
Oracle silver bullet tuning is a top-down
approach where a global change can have a profound positive impact
on Oracle database performance. Jeff Moss, an Oracle DBA from the UK reports in
a publication titled “IO
problem!” that an external disk bottleneck was hurting his overall
Oracle performance:
“the temporary
tablespace datafiles were on a filesystem which was marked as a
archive redo log area on the RAID array and were set up as a
concatenated volume rather than a stripe….with obvious performance
impact!”
By analyzing statistics and creating
a prediction, Moss was able to predict that his I/O was about
50x too slow:
“It will take a
while to organise the array reorganisation to fix the problem but it
should boost performance since the current stats are showing that
it’s about 50 times slower service times on that part of the array
than the place the files are supposed to be at.”
In a subsequent publication titled “What
a boost!", Moss notes that this single reorg made his batch suite
run time go down from 12 hours down to only 4 hours:
“The temp tablespace area on that IO issue was reorganised a few days ago and the batch suite has reduced in time
from 12 hours to 4...with more to come from the ability to
parallelise more of the jobs now that the system isn't bottlenecking
on temp.
Much Better.”
The idea behind Oracle
Silver Bullet Tuning is an approach where a suboptimal
system-wide element is identified and the “Silver Bullet” is the
single action that results in a profound positive change to an
entire Oracle database.
Laurent Schneider notes in Oracle MOSC an Oracle silver bullet
technique where changing two Oracle initialization parameters made
his SQL query performance increase more than 8x faster:
"I set appropriate values for pga_aggregate_target and
_pga_max_size...
alter system set pga_aggregate_target=6G;
alter system set "_pga_max_size"=2000000000;
...and I gave the query some hints "NOREWRITE FULL USE_HASH
ORDERED".
As a result, it boosted my query performance from 12
hours to 1.5 hour."
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Oracle Silver bullets can be external remedies such as
fixing sub-optimal RAID or they can be internal techniques
such as adjusting Oracle parameters, adding super-selective
indexes or using materialized views. Don Burleson notes these Oracle Silver Bullets
and many more in his latest book “Oracle Silver Bullets: Real-world
Oracle performance Secrets”. It’s only $19.95 and you can buy it
directly from the publisher at this link: |
http://www.rampant-books.com/book_0501_silver_bullet.htm
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