MapServer Oracle - MS or OGR?

[Frank Warmerdam]

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 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.

 >  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.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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