On Mar 30, 2006, at 9:41 AM, Frank Warmerdam wrote:
William Kyngesburye wrote:
I'm wondering how MapServer's builtin Oracle support is different
from OGR's? Feature support and performance.
William,
I think the main downside of OGR Oracle support is performance. Going
throug the extra "OGRFeature" layer has to cost something. The other
issue I think is that the direct access in MapServer allows the user
to specify a highly customized query but still have MapServer add
the spatial component to it, so that all the query is done in Oracle.
If you go through OGR you have two choices. If you use a custom query
then then OGR is too dumb to know how to add the spatial component
into
it and so (I assume) the spatial query is done in OGR after fetching
from the DB. If you just use normal table access with (with perhaps a
simple WHERE clause in your FILTER) then OGR will pass the spatial
query
into Oracle to resolve.
I kinda figured it might be something like that.
I would rather use Oracle from GDAL. My concern is that Oracle
support is fixed into the MapServer binary, either it has it or it
doesn't. No plugin mechanism in MapServer (or is there?).
In 4.8 there *is* a plugin mechanism but the build architecture has no
particular support to utilize it to make something like the oracle
driver
a plugin. So it is practical, but not terribly easy, to make the
oracle
support a plugin for mapserver.
Is there any documentation on the hidden plugin mechanism? All I
found on the MS site was an RFC to add this feature.
> If it does, a user must
install the Oracle Instant Client to use MapServer even if they
don't use Oracle (tho there is the weak link trick in Darwin).
But with OGR, one should be able to build Oracle support as a
plugin, much like the GRASS plugin (I plan to try it for my next
GIS Libs for Mac OS X).
Right.
I'll probably keep doing the weak-link thing for now, until I figure
out the plugin mechanism.
-----
William Kyngesburye <[EMAIL PROTECTED]>
http://www.kyngchaos.com/
First Pogril: Why is life like sticking your head in a bucket filled
with hyena offal?
Second Pogril: I don't know. Why IS life like sticking your head in
a bucket filled with hyena offal?
First Pogril: I don't know either. Wretched, isn't it?
-HitchHiker's Guide to the Galaxy
