[GRASS-dev] better mysql support

[Paul Kelly]

On Mon, 16 Apr 2007, Emanuele Conti wrote:

> So, can anyone explain the meaning of the first two points in this feaure
> list <http://grass.itc.it/grass60/index.php#features> of grass6, where there
> is a direct and explicit mention to postgis?

I'm not sure. The first point explicitly says the interface to PostGIS is 
through OGR. PostGIS export/import does indeed have a bullet point to 
itself - but note it does say export/import - meaning that the geometry is 
still converted to/from GRASS native format. I'm not sure why its there. 
Note that the page is for 6.0, which is quite old now. It may be a 
confusion over the direct PostGIS support which has been recently removed 
then, or it may simply refer to importing/exporting from/to PostGIS via 
OGR.

This message may be interesting to you about the limitations of the old 
(GRASS 5.7) PostGIS support:
http://grass.itc.it/pipermail/grass5/2003-October/012808.html
In particular, it implies that the reason it was slow was because of the 
way GRASS queried PostGIS, not PostGIS itself. So if you query MySQL 
spatial in the same way, you would not get any speed improvement because 
the bottleneck was the interface between GRASS and PostGIS. Or, looking at 
it another way, if you get it to work fast with MySQL then it would 
probably also work fast with PostGIS.

As is probably obvious here, I only understand most of the issues involved 
at a superficial level but am trying to point out where you should read 
around to get more information.

Paul