On 20 Apr 2009, at 20:37, Ron Phelps wrote:

> Have a database with a lot of data. To simplify plotting I would
> like to
> "filter" every nth row. Is there a way using a select statement to
> accomplish this?

It really depends what kind of picture you want. Generally, the best
approach for looking at large collections of data involves
aggregation. So instead of sampling, I would look at what axes you
are plotting against and what the resolution of your display is and
try aggregating on the plotting axes at a level of detail that matches
your display. For example, if you have time series data over a year
and only 365 pixels of resolution on the x-axis, there is no point in
aggregating at anything below the day level because you won't be able
to see it. Then you decide whether you want the sum or average of
your measure on the Y axes etc.

If this sounds daunting, you could try using Tableau ;-) We talk to
Firebird (2.0+) servers and have a lot of best practices for this sort
of thing built in.

HTH
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Richard Wesley Senior Software Developer Tableau
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