Re: Mathematica RDBMS Model

Michal Widera wrote:
> Jan Hidders wrote:
> > Michal Widera wrote:
> > > Jan Hidders wrote:
> > > > Michal Widera wrote:
> > > > >
> > > > > Is there anybody knows something about mathematical (queued
> > > > > maybe...) model of simple RDBMS ?
> > > >
> > > > What kind of model are you looking for? [...]
> > >
> > > I'm looking for a simplified theoretical model of database
> > > engine.
> >
> > So the next question is what you want the granularity of the model
> > to be? [...]
>
> Well, i think that the model should be projected step down - from the
> black box to the most posible granuarity. In first aprox. i think
> that the simple queriers should be black box'es, there also should be
> some kind of process modeling. (Data base writter, Listener,
> Archiver, etc... like internal structure of Oracle Database) What
> kind of matematic tool i'll use - it still open problem. I think
> about construct a simple M/M/1 ? What you think about it ?

Oh. So you want a statistical model! The question is of course how appropriate such a model would be. The assumptions of the M/M/1 model are probably not very valid; the queues esentially are FIFO queue but transactions can be postponed if they need a lock that is not free. But of course you can make some general assumptions about this like "in 90% of the cases the lock will be available" or "if a lock is not available it usually becomes so in a few secondes" but that is not very realistic, especially if you want the model to describe accurately what happens tot the database under a heavy load.

So the central question has to be: what is it that you would like to achieve with this model? How realistic do you want it to be? How complicated do you want it to be? Obviously there is a trade off here.

-- 
  Jan Hidders