[postgis-users] MapServer with PostGIS: motivations

[Brent Wood]

I've been following this thread with some interest, 

I have a vector topo dataset for New Zealand, which includes 20m elevation
contours. On A64 hardware with 64 bit Linux OS, I have compared speeds with
shapefiles & PostGIS. About 700Mb of shapefile for this one layer.

Shapefiles are faster when you plot the entire map as a simple draw, but when
it becomes a layer with classes to provide color bands based on elevation,
using PostGIS queries to set up each class, it was MUCH faster than using
shapefiles.

Which is just an example confirming Frank's comments! The more you want to
subset or interact with your data, the more you'll benefit from PostGIS. If you
have static data and simple map layers, shapefiles are likely to be faster.

I have found Postgis runs faster on Linux than Windows on the same hardware,
the OS caching of data under Linux seems to give Linux a serious advantage.
Using a fully 64 bit OS & compiling all the apps as 64 bit applications also
gives a performance gain, which seems to benefit PostGIS performance over
shapefiles.

My initial reason for using PostGIS over shapefiles was simply to use a
database to manage spatial data. Shapefiles store it & provide it, but don't
manage it :-) 

Using this platform I have yet to have any performance issue using PostGIS
which required me to use Shapefiles, and the benefits for having data in a
database are why databases were invented :-)


Cheers,

  Brent Wood