shptree & .qix files

[Ben Madin]

G'day all,

I have a very large shapefile, which with various queries to produce  
a multilayered map depending on data in a MSSQL database is taking  
145 seconds to render a map (using php/mapscript). A simpler (but  
still 50MB) shapefile is producing a map in about 2 secs. The time is  
all in the $map->draw() statement, so looking around for ways to  
speed it up, i realised that it wasn't indexed.

After running shptree on it, and getting a .qix file, it was taking  
just as long... aha you say, and yes, you were right, I was still  
calling "map.shp"!

So I changed that to just "map", and now it takes 194 seconds?

Needless to say, I changed it back to .shp, back to 145 seconds.

My understanding (from the mapserver site) is that shapefiles are the  
default format for mapserver, and that creating an index should speed  
them up, not slow them down. have I misinterpreted this, or am I way  
over my head. The queries in MSSQL are taking negligible time, the  
php script is taking negligible time, this is over a wireless LAN, so  
it must be the mapserver engine.

I appreciated Stuart's suggestions for speed, but we have already  
given up reprojection, and none of these files have any projection  
associated with them as far as I can tell... how can I tell?

cheers

Ben



-- 

Ben Madin
Remote Information Pty Ltd

t/f: 08 9192 5535
m: 0448 887 220
ben at remoteinformation.com.au