[Mapserver-dev] Re: [UMN_MAPSERVER-USERS] Oracle Spatial Performance

[FERNANDO SIMON]

Hi developers,
    First, introducing myself again I'm Fernando Simon indicaded by Rodrigo
Cabral and now I'm contining his work as a developer of maporaclespatial and the
reponsable of to give the support to the Oracle Spatial users.
    I'm following the colloquy, I intend to add the characteristc described by
Paul Ramsey to the new version.
    About this new version, I belive that I will finisht it this week, this
version allow the user query items directly to the database as Postgis. So, it's
 possible use the functions as "querbyattributes" by Mapscript.
    In the future my suggest it's just to add to the support the multipolygon
objects, and other types of objects.
    If you have more suggest to add to this new version, write me.
    Thank's for the attention.


-------------------------------------------------------------------------
Fernando Simon - simon at inf.univali.br
G10 - Laboratorio de Computacao Aplicada - Brazil
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Quoting Paul Ramsey <pramsey at refractions.net>:

> Any reason not to simply apply this change to the standard source?
> 
> On Sunday, September 26, 2004, at 05:47 AM, Smith, Michael  
> ERDC-CRREL-NH wrote:
> 
> > It is also very important for performance reasons to increase the  
> > array size in maporaclespatial.c and recompile. We generally recommend  
> > setting array size to ~ 1000. We generally see an order of magnitude  
> > increase in speed with this change.
> >
> > Mike Smith
> > USACE-CRREL
> > Remote Sensing GIS Center of Expertise
> > Hanover, NH
> >
> > -----Original Message-----
> > From: Frank Warmerdam
> > To: MAPSERVER-USERS at LISTS.UMN.EDU
> > Sent: 9/25/2004 7:34 PM
> > Subject: Re: [UMN_MAPSERVER-USERS] Oracle Spatial Performance
> >
> > Vladimir Guzmán wrote:
> > > Hello, List.
> > >
> > > I don't know if this is an off-topic question but, I really need some
> > help.
> > > I've worked a lot with mapserver, specially with phpmapscript, and
> > with
> > > shape files and postgis data.
> > > Finally, about 6 months ago, we received a request from a customer in
> > > order to develop a web application that would be able to connect with
> > > oracle data.
> > > Well, after face all kinds of issues with oracle spatial, everything
> > is
> > > working fine now.  Except the speed.
> > > Every map request to oracle spatial takes at least 20 seconds, with
> > very
> > > small geometries, and in some cases it takes 2 minutes or more.
> > > I would like you to give me some clue, because I've worked with
> > postgis
> > > and shps and I've never had this kind of problems.
> > > All the geometries are indexed.
> > > The time responses are almost the same working with ORACLESPATIAL and
> > > OGR connection.
> > >
> > > For example:
> > > The command:
> > > ogrinfo OCI:xxx/xxx at xxx -sql "SELECT ID, ORA_GEOMETRY, NOMBRE FROM
> > > SIG_DEPTOS"
> > > Takes 1 minute.
> > > The same geometry in shp:
> > > ogrinfo -al departamentos.shp
> > > Takes less than one second.
> >
> > Vladimir,
> >
> > I can think of a couple of issues.
> >
> > First, the connection overhead to Oracle tends to be pretty expensive.
> > In my work it was several seconds to a local Oracle instance.  When
> > using
> > MapServer in "cgi" mode where a new process is forked and needs to
> > connect
> > to Oracle for each map request the extra overhead can be quite
> > devestating.
> > The presume solution to this is to keep the process resident, for
> > instance
> > by using FastCGI and caching the oracle connection.  This is currently
> > not supported by MapServer, but I am working on FastCGI support again  
> > on
> > behalf of Refractions and so a solution may become available in the
> > coming
> > months.
> >
> > Second, by default OGR will collect schema information from all the
> > tables (or at least spatial tables) in your database. This can be very
> > expensive for a database with alot of tables.  However, this issue is
> > unique to OGR connections to Oracle, and should not occur with the more
> > direct Oracle support in MapServer.
> >
> > 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    | Geospatial Programmer for Rent
> >
> >
>       Paul Ramsey
>       Refractions Research
>       Email: pramsey at refractions.net
>       Phone: (250) 885-0632
> 
> 
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> 




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