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From Dirk-Willem van Gulik <Dirk-Willem.van.Gu...@bbc.co.uk>
Subject Re: Statistics Module
Date Sat, 31 Jan 2009 11:40:21 GMT
Paul Davis wrote:

>  >> The way that stats are calculated currently with the dependent
>  >> variable being time could cause some issues in implementing more
>  >> statistics. With my extremely limited knowledge of stats I think
>  >> moving that to be dependent on the number of requests might be better.

> Code looks awesome. For reference, they're storing the last N samples
> with each time point over a given time period. Ie, they store the
> current counter values once a second.

Eh - do you really want to build RRDtool/cacti/nagios/zenoss/mrtg like 
capabilities in your database ?

I'd say - focus on getting the data out (ideally as _counters_) and let 
the monitoring tools figure out the rest. They know their polling 
intervals and what not (some dynimically adjust) and can figure out how 
to sample, calculate rates, do stats and what not. And can have fairly 
refined windowing techniques to aggregate (e.g. rrdtool).

So do not try to make a stats module - try to make a module that output 
the data on which you can base your starts :).

I.e. when you can have:

	database_opened		counter
	database_closed		counter

you can work out 1) rate of open/close, 2) the number currently open and 
do all sorts of post processing. Whereas a float giving you some rate 
over some unknown window is not nearly as useful.

Dw

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