[mod_python] Re: Graphs in a webpage

Gregory Trubetskoy grisha at modpython.org
Wed Nov 15 21:35:42 EST 2000

This is somewhat off-subject, but IMHO the best tool for time-series data
storing and charting is RRDtool. It can produce charts for a year of data
in a split second.


On Wed, 15 Nov 2000, Graham Swallow wrote:

> On Tue, 14 Nov 2000, Alexis Iglauer wrote:
> > My datafiles are time series data, usually for 24
> > hours at a time, so I will have a whole bunch of
> > datafiles which make up a contiguous set of data over
> > several days/months/years.
> 	I have a similar situation, but not in apache_mod.  The data is
> 	an array of floats (binary portable), one every minute for a week,
> 	over the year.
> 	Repackaging last weeks data is slow, but you dont do that for
> 	every request.
> 	I use Array to get it as a string, then I use zlib to get a string,
> 	then I 'escape' the data for MySql (using the standard function)
> 	and write it into a blob field.
> 	The data comes back with no need for un-escaping (its so that it
> 	goes into an SQL statement).
> 	Then I call a C function to convert the floats to doubles and
> 	create a BLT/Vector. Its very quick.
> 	Using GD (or whatever) should not be slow, but a bit of C at the
> 	right place means you move chunks of data around, not iterate
> 	python over thousands of items.
> 	The 'most recent' file obviously needs special treatment.
> 	You could re-process today every hour (hint: move, start new file,
> 	then process the moved file, if fail - dont delete).
> 	That still leaves you with a 'double' data source, first SQL, then
> 	the additional file.  Alternatively, get the data collector to
> 	post the data ...
> 	Graham
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