[postgis] Line Thinning

John Reid jgreid at uow.edu.au
Tue Mar 19 22:34:17 PST 2002

Paul Ramsey wrote:

>I'd just like to quickly point out that Line Thinning on the fly, while
>not a bad thing, is a bit of a red herring in the pond. No matter how
>aggressively or inteligently you thin, if your result set consists of 2
>million records, you will not be getting interactive performance from
>your database anymore.
>Probably an intelligent browsing client, when told to 'look at that
>spatial database' would do a quick (or not so quick) 'select count(*)'
>from each spatial table, and a 'select extent(*)' from each spatial
>table, then cache those results as a first order approximation of how
>much data it is dealing with in each table. From there it could make
>some smart choices about what to display/not display when zoomed to
>'full extents'.
>When such a thing exists, that is :)
If this is done at load time using a seperate geometry column for each 
target resolution, this is no longer a problem?  Load time would take a 
big hit (not to mention disk space), but the task could be performed 
recursively which would speed things up a bit.

Maybe implemented as an option in a Java loader with a plugin 
architecture calling style sheets to do the dirty work.  Any XML 
Schema/RDF experts comment on my naive take on stylesheet capability? 
 Portability/flexibility/maintainability might be more important 
compared to the speed of C/C++, for this task anyway.

Just an idea to maybe put in the "one of these days" basket....


john reid                                     e-mail jgreid at uow.edu.au
uproot your questions from their ground and the dangling roots will be
seen.  more questions!
                                                       -mentat zensufi

apply standard disclaimers as desired...

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