[Zope-dev] how bad are per-request-write-transactions

[Ivo van der Wijk]

On Wed, Apr 17, 2002 at 07:54:04AM -0400, Paul Everitt wrote:
> 
> I don't agree that high write is always forbidden.  I think there are 
> plenty of cases where this can work.  It simply becomes unworkable much 
> sooner than other data systems (e.g. a relational database or FS-based 
> solution).
> 

First of all, what the product does is, besides accounting the number of 
objects and their total size, measure traffic / number of hits. This way,
zopehosters (like us) can measure the traffic generated by customers and
optionally block further traffic.

> For instance, think about bloat for a second.  Let's be crazy and say it 
> takes 100 bytes to store an integer representing a count.  Let's say you 
> write once a second.  That's under 7Mb a day (per counter).  Combined 
> with hourly packing, that might be well within limits.
> 

I'd still rather avoid such numbers

> Let's take the next step and say that you can live with a little 
> volatility in the data.  You write an object that caches ten seconds 
> worth of writes.  Whenever a write comes in at the over-ten-second mark, 
> you write the _v_ attribute to the persistent attribute.  There's an 
> order of magnitude improvement.

This sounds like a good solution. Actually, I only have to write to the
persited attribute if the object is persisted itself (i.e. in setstate),
until then, I'll just add the self._counter and self._v_counter, right?

> 
> Finally, you store all your counters in a non-versioned storage.  Now 
> you have *no* bloat problem. :^)
> 

How would this work? (Wouldn't this be a solution for some of the HelpSystem
issues as well?)

Cheers,

	Ivo

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