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From Piumi Nanayakkara <piumi.t...@gmail.com>
Subject Re: Modifying "sql join" optimization algorithm in Derby
Date Fri, 10 Jun 2011 17:17:37 GMT

Thank you very much for your responses.

Our tentative plan is to change currently available optimization techniques
in relation to seek time/rotational latency which comes with the normal
magnetic disk,but can be avoided in solid state memory device. Initially we
are focusing on the optimization of Join operation in Apache Derby. We
thought of first comparing the performance in two modes of devices with
existing algorithms ( i.e. Nested Loop Join and Hash Join) & existing join
order and then to modify them to utilize the benefits of solid state

we highly appreciate any feedback on this or any suggestions of an
alternative approach that can be taken.

Best Regards,
Piumi Nanayakkara

On Fri, Jun 10, 2011 at 7:37 PM, Rick Hillegas <rick.hillegas@oracle.com>wrote:

> On 6/10/11 1:07 AM, Piumi Nanayakkara wrote:
>> Hi all,
>> For a research purpose I'm considering $subject when database is stored in
>> a solid state device.Can some one please clarify me the packages/classes
>> that i should study/modify for this purpose.
>> Thank You!
>> Best Regards,
>> Piumi Nanayakkara
> Hi Piumi,
> Probably what is most relevant is the Cost Model for these devices. Derby
> ships with a hard-coded Cost Model for heap and index files. That Cost Model
> was tuned many years ago and probably doesn't capture the actual performance
> of modern disks. I was not part of the effort to tune that Cost Model so I
> can't give you a lot of detail here.
> If you want to tweak the Cost Model to better reflect the performance of
> solid state disks, I recommend that you study the
> org.apache.derby.iapi.store.access.StoreCostController interface and its
> implementations. Unfortunately, I am not aware of any tools which will help
> you create an implementation which is tuned to the behavior of a particular
> disk. You may develop such a tool as you pursue your research. If so, I
> encourage you to donate that tool back to the community. I'm sure it will be
> useful to other researchers and developers.
> Perhaps you will get more detailed advice from someone who was closer to
> the original effort which tuned the current Cost Model.
> Sounds like an interesting project. Good luck!
> Cheers,
> -Rick

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