[postgis-users] Re: [mapserver-users] MapServer Performance

[Vinko Vrsalovic]

On Thu, Nov 21, 2002 at 09:02:40PM -0800, Paul Ramsey wrote:
 
> Check out some of Jan's postings in the past regarding doing 
> classification on the fly from PostGIS. One of the keys to good 
> performance is pushing the calculations back into the database. So 
> rather than adding X classes with expressions in them, do the 
> classification in the db with a CASE expression and simplify the class 
> expressions down the a CLASSITEM and a simple match (EXPRESSION "blah").
 
Ok, I'll look at that, but I can't find Jan's postings about
classification on the fly, could you please point me to the month,
subject or URL for those articles?
 
> Also I do not entirely understand what is going on in steps 1 and 2. You 
> are adding to the db for every query?

For every access that needs to classify the data (there are some which
don't need that). The problem is that the data comes from another DB
(Oracle) in another machine (a Sun machine) in another application
(independent from the one I'm implementing). So I need to retrieve the
data from that application, and then classify the features according to it.

> Finally, you do not need views necessarily since you can now form a DATA 
> statement out of arbitrary SQL. I am afraid we still do not have a 
> comprehensive guide on this topic yet... sorry.

In the CVS for MS 3.7? PostGIS 0.7.3?

I'm now running on PostGIS 0.7.3 with MS 3.6...

Is there a simple example at least?

Thanks!,
-- 
Vinko Vrsalovic <el[|- at -|]vinko.cl>
http://www.cprsig.cl