Speeding up the visualization of a shapefile with more than one million of lines

[Gregor Mosheh]

Luca Manganelli wrote:
> Thank you for the reply. I have already seen those pages: I have
> already tiled the big shp (42 MB) into 8x8 pieces.

> But my question is:
> at the highest scale, rendering an 8x8 shp of 42MB is slow.

Well, that's not a question, just a fact. :)
Seriously, though:

Have you run shptree to create a spatial index? If so, are you sure that 
your shapefile is NOT specifying the .shp extension?
   Wrong:
     DATA "streets/tiger.shp"
   Right:
     DATA "streets/tiger"

And what about your mapfile's classifications? Is the map drawing every 
street segment with every request? That can be a killer! Use classes to 
break them up into highways for large views, and streets for closer-up 
views. If you're already using a spatial index, then most of the time is 
probably not scanning the shapefiles but rather in drawing the shapes, 
so let's see the appropriate mapfile layer.

-- 
Gregor Mosheh / Greg Allensworth
System Administrator, HostGIS cartographic development & hosting services
http://www.HostGIS.com/

"Remember that no one cares if you can back up,
  only if you can restore." - AMANDA