[Mapserver-dev] Re: [Mapserver-users] Mapscript drawQuery() on big PostGIS layers doesn't work properly ?

[Daniel Morissette]

David Blasby wrote:
> 
> It could be possible to have msLayerWhichShapes()  (a query-by-rectangle 
> with filter) cache the results so that msLayerGetShape( <record number> 
> ) works quickly.
> 
> I think that mapserv doesnt call msPOSTGISWhichItems() (or sets the 
> items list) until *after* the  query-by-rectange, so I dont know what 
> columns to grab from the DB.
> 
> I dont know why there's a separate query mechanism is mapserv - why 
> doesnt it just call msLayerWhichShapes() then msLayerNextShape() like 
> the normal drawing routines?  It seems there's twice as much code to 
> maintain than necessary.
> 

Um... it is likely that the rendering code and the query code don't do 
things the same way (I didn't check), that could explain the problems 
that you had.

I'll stop talking now before I say too many lies... it seems that 
someone will need to revisit the maplayer.c stuff with databases such as 
postgis in mind and see what can be done either in maplayer.c or in 
mappostgis.c.  Perhaps you could file a bug with today's discussion to 
make sure we don't forget.

-- 
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  Daniel Morissette               morissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/
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