Re: reads which modify data

You described the solution yourself:

Make the randomness pseudo-random using a seed. So now you are simply
doing lazy-eval in your queries, which is ok. You just have to
manually sync that, of course, which sounds simple to do in your case.

What am I missing?



On Sun, Mar 1, 2009 at 1:03 PM, Justin T. Sampson <[email protected]> wrote:
> To take your example literally, why wouldn't you apply the random damage
> during the write operation, at the moment the velocity drops to zero?
>
> -Justin
>
>
> On Sun, Mar 1, 2009 at 5:48 AM, hakan eryargi <[email protected]>
> wrote:
>>
>> hello,
>>
>> how would you design a system where some reads modify the data in an
>> undeterministic way ? undeterministic means random here and can be
>> translated into a deterministic one by supplying random seed from
>> outside.
>>
>> one can say, these are actually writes not reads, so must be handled
>> as transactions. the answer is there are so many of them so we cannot
>> simply afford handling them as transactions. and a very very little
>> proportion of that reads cause such random modifications.
>>
>> these reads trigger lazy calculations as described in this thread:
>>
>> http://www.nabble.com/Re%3A-execution-order-of-queries-and-transactions-p17049169.html
>>
>> continuing the sample in that thread: think of a moving entity. a
>> write operation modifies its acceleration and direction, read
>> operation calculates current velocity and position and returns them.
>> no matter how many times you read the velocity, it will be the same at
>> some specific point in time.  it's ok till now. now add another
>> feature that when entity's velocity drops to zero it takes some random
>> damage. so when velocity or position is read, there is a chance that
>> this will trigger a damage.
>>
>> how would you persist such a system with prevayler ?
>>
>> regards,
>> r a f t
>>
>>
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>
>
>
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>
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> -Receive a $600 discount off the registration fee with the source code: SFAD
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-OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise
-Strategies to boost innovation and cut costs with open source participation
-Receive a $600 discount off the registration fee with the source code: SFAD
http://p.sf.net/sfu/XcvMzF8H
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