I'm a little surprised by the scale of the improvement.
It would have been interesting to find out where the difference came from, I
would expect some time from the increased latch activity of having to populate
4 times as many buffers, and some write effects from having to write 4 times as
many buffers, and if you didn't set the chunksize to 32K for the 8KB block test
there would be some excess in having 4 x extra calls to db file sequential read
compared to one db file parallel read.
I wonder if it's related to something I've had on my todo list for the last 11
years - why creating a context index on bfiles takes MUCH longer than creating
a context index on the same data when it has been loaded as CLOBs: I have a
note to myself that there was a "missing time" component that might be
something to do with bfile seeks - maybe your 20% was something to do with
fewer seeks when reading 32KB at a time. I may have to dust the test case down
and bring it to the top of my list :(
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
@jloracle
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx [oracle-l-bounce@xxxxxxxxxxxxx] on behalf
of Sheehan, Jeremy [JEREMY.SHEEHAN@xxxxxxxxxxxxxxxxx]
Sent: 01 October 2015 22:53
To: Kevin Jernigan; contact@xxxxxxxx; oracle-l@xxxxxxxxxxxxx; oralrnr@xxxxxxxxx
Subject: Re: Bigger block sizes
Basic files about 8 years ago.
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From: Kevin Jernigan <kevin.jernigan@xxxxxxxxxx>
Sent: Oct 1, 2015 4:59 PM
To: Sheehan, Jeremy; contact@xxxxxxxx; oracle-l@xxxxxxxxxxxxx; oralrnr@xxxxxxxxx
Subject: Re: Bigger block sizes
With BasicFiles or SecureFiles? -KJ
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Kevin Jernigan
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On 10/1/15 9:17 AM, Sheehan, Jeremy wrote:
Orlando,
I did testing and implemented a BLOB tablespace with 32K blocksize and I saw
about a 20% increase in performance when saving and retrieving files into a
blob column.
Jeremy
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Stefan Koehler
Sent: Thursday, October 01, 2015 12:03 PM
To: oracle-l@xxxxxxxxxxxxx; oralrnr@xxxxxxxxx
Subject: Re: Bigger block sizes
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Hi Orlando,
it depends (as always).
Franck Pachot has written a great blog post with several demos about this
topic: http://blog.dbi-services.com/do-the-block-size-matter/
Best Regards
Stefan Koehler
Freelance Oracle performance consultant and researcher
Homepage: http://www.soocs.de
Twitter: @OracleSK
Orlando L <oralrnr@xxxxxxxxx> hat am 30. September 2015 um 23:29 geschrieben:--
List,
Does anyone in the list use non default blocksize of greater than 8K for
your oracle DBs; if so, is it for warehousing/OLAP type applications?
What advantages do you get with them; any disadvantage.
Orlando.
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