[Gdal-dev] Performance on using Oracle Client XE

Frank Warmerdam warmerdam at pobox.com
Fri Nov 10 17:09:35 EST 2006

Wong Taka wrote:
> Dear All
> I am now studing a project about using mapserver to display map.
> In this map, points would be also shown. These points' XY and other info 
> are stored in relational Oracle XE DB. For displaying, these point can 
> be generated in acceptable time.
> However, when I retrieve the Points' attributes by grab the point in 
> map. I found that the loading time is quite long. I have tried to add a 
> index in Oracle XE for the XY in the table. It seems indifferent in 
> performance.


I'm not sure what you mean by retreiving the points attribute
by grabbing the point in the map.   Also, are you using the Oracle
OCI driver in OGR, or the CONNECTIONTYPE ORACLE support built into

I will note that the MapServer "query" mechanism is two pass, and
that if going through OCI it requires a seperate SQL SELECT
statement to be executed for each feature fetched.  This is
needless to say fairly expensive.  This is in contrast to how
layers are drawn where a single select is done, and all the
rows are pulled in sequence.

I suspect this is the pit you are falling into.

> Are there any smart way to improve the performance? e.g. did fastCGI 
> work? since I am using IIS to run Mapserver. I wonder.

If it is the problem above, then you are best off avoiding the
two pass query mechanism.  How to do this will depend on your
particulars.  If you are writing a mapscript application, you
may find it better to do something kinds of queries to oracle
directly from your scripting language of choice rather than
through mapserver.

> by the way, I think this post should be post on MAPSERVER mail list, 
> and I have tried also, but it always bound my post back. -_-"

You need to be very careful to subscribe using the email
address you will post from.   I suspect the same thing
happened to you with gdal-dev, and the post was held till
I approved it manually.  There is no manual approval for
the mapserver list as far as I know.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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