[mapserver-dev] mappostgis.c

[Paul Ramsey]

On Tue, Nov 4, 2008 at 10:54 AM, Steve Lime <Steve.Lime at dnr.state.mn.us> wrote:
> A good threat, probably long overdue. Do you have any feel for the performance end of things? I
> recall the Geoserver tests showing GeoServer performing substantially better than MapServer w/regards
> to PostGIS.

OK, this isn't testing against Geoserver, just against 5.2, and the
result is, 5.4trunk is maybe 5% slower. Which is not unsurprising,
since now the geometry is transiting a text encoding on the way. I had
my fingers crossed that the simpler database handling would speed
things up, but no go.

In terms of straight-up profiling information:

25% of cycles are still spent in pj_init, and this is *after* I moved
the two relevant EPSG codes to the top of the file. Geoserver has
objects cached.
20% of cycles are spent in image compression (gif or png). The
Geoserver ImageIO might have optimized image compressors (my work with
IPP impresses on me how much gain is available in this area).

The penalty for parsing the proj4 definitions every time, even for
layers that aren't being drawn, is certainly high, and of course grows
the more layers you have.  However, these overheads also exist in the
shape file chain, so the difference between PostGIS and Shape relative
to Geoserver remains unexplained.

P.