[mapguide-users] Base Layers that are based on Oracle Spatial data

Thu Aug 3 13:00:50 EDT 2006

I am pretty sure it does an immediate delete of all cached files for the
given map, so there will be an I/O hit. Fragmentation is a concern but
it's hard to say exactly what the impact would be.

Bob

  _____  

From: Butler, Juan P [mailto:jpbutler at co.pinellas.fl.us] 
Sent: Thursday, August 03, 2006 10:40 AM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Base Layers that are based on Oracle
Spatial data

Jason:

You think there is that much of a problem with fragmentation?   We do a
similar process now with picture/data files where we delete them.  We do
this because of the older system we are migrating from.  I was hoping
that I would not have to do this with Enterprise, but it's not that big
of a deal if I can just automate it.  I don't see an IO hit or
fragmentation problem now.   

Juan Butler - Senior Programmer/Analyst
GIS Applications
Pinellas County Information Systems
jpbutler at pinellascounty.org

Please note: All mail sent to and from Pinellas County Government is
subject to the Public Records Law of Florida.

  _____  

From: Jason Birch [mailto:Jason.Birch at nanaimo.ca]
Sent: Thu 8/3/2006 12:20 PM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Base Layers that are based on Oracle
Spatial data

Bob,

Does that method actually delete all the files in the cache, or just
mark them as stale?

I'd be worried about the IO hit and volume fragmentation resulting from
a bulk delete.  It would be better if the server would overwrite
existing tiles with modified dates < the date the cache was last
invalidated.

Jason

  _____  

From: Robert Bray [mailto:robert.bray at autodesk.com] 
Sent: Thursday, August 03, 2006 07:35
To: Butler, Juan P; users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Base Layers that are based on Oracle
Spatial data

Juan,

Tile Service has the following method: 

virtual void 

ClearCache
<file:///C:\Program%20Files\MapGuideOpenSource\WebServerExtensions\Help\
df\dba\class_mg_tile_service_16adf9e13f5acc6439571b348180265e.html#16adf
9e13f5acc6439571b348180265e>  (MgMap
<file:///C:\Program%20Files\MapGuideOpenSource\WebServerExtensions\Help\
da\df8\class_mg_map.html>  *map)=0

Clears the entire tile cache for the given map. Tiles for all base map
layer groups and finite scales will be removed.
<file:///C:\Program%20Files\MapGuideOpenSource\WebServerExtensions\Help\
df\dba\class_mg_tile_service.html#16adf9e13f5acc6439571b348180265e#16adf
9e13f5acc6439571b348180265e> 

All you need is a little PHP script that connects to the server and
calls this method. Then schedule to run that script once a week, once a
month, or on whatever schedule you feel appropriate. For an example of
how to write such a thing, look in the RepositoryAdmin folder that lives
underneath the server install folder. 

Bob

  _____  

From: Butler, Juan P [mailto:jpbutler at co.pinellas.fl.us] 
Sent: Thursday, August 03, 2006 8:09 AM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Base Layers that are based on Oracle
Spatial data

Exactly Jason...Like our road layers.   I'm not saying there are many
updates but there enough updates to be worried about the correct data
being displayed.   I was seeing a benefit of using the tiles for our
roads because of the high use of this layer.

I guess I have my answer and I'll have to either not use tiles at all or
just manually delete them so they can be rebuilt.  

Juan Butler - Senior Programmer/Analyst
GIS Applications
Pinellas County Information Systems
jpbutler at pinellascounty.org

Please note: All mail sent to and from Pinellas County Government is
subject to the Public Records Law of Florida.

  _____  

From: Traian Stanev [mailto:traian.stanev at autodesk.com]
Sent: Thu 8/3/2006 9:07 AM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Base Layers that are based on Oracle
Spatial data

Yes, I imagine there is a point at which base layers make more sense in,
like you say, high levels of usage.

  _____  

From: Jason Birch [mailto:Jason.Birch at nanaimo.ca] 
Sent: Wednesday, August 02, 2006 11:19 PM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Base Layers that are based on Oracle
Spatial data

I don't have much experience with tile caching and the new MapGuide, but
if the data is only being updated once per day or once every few days,
and you have high levels of usage on your web app, I'd have to believe
that you would get some kind of performance return from only having to
render those layers when they are actually modified...  Hmm.  I think
that was a run-on-sentence.

Jason

  _____  

From: Traian Stanev [mailto:traian.stanev at autodesk.com]
Sent: Wed 2006-08-02 8:10 PM
To: users at mapguide.osgeo.org
Subject: RE: [mapguide-users] Base Layers that are based on Oracle
Spatial data

If the layer will be changing a lot, is there any point for it to be a
base layer at all? Just make it a regular dynamic layer... 

	-----Original Message----- 
	From: Jason Birch [mailto:Jason.Birch at nanaimo.ca] 
	Sent: Wed 8/2/2006 10:12 PM 
	To: users at mapguide.osgeo.org 
	Cc: 
	Subject: RE: [mapguide-users] Base Layers that are based on
Oracle Spatial data

	It would be useful to set a property on the layer like
InvalidateDate that would force tile-replacement for tiles that are
older than that date.  If this feature was available, it would be
possible to set up a trigger in Oracle to invalidate the tile cache for
affected layers.  I'd prefer this method to just deleting the cache,
because of the huge file IO caused by the delete, and because it would
reduce fragmentation of the volume.  This would be usable by other
external processes, such as daily SDF updates via FME, etc...

	Jason

  _____  

	From: Traian Stanev [mailto:traian.stanev at autodesk.com]
	Sent: Wed 2006-08-02 4:42 PM
	To: users at mapguide.osgeo.org; users at mapguide.osgeo.org
	Subject: RE: [mapguide-users] Base Layers that are based on
Oracle Spatial data

	As far as I understand it, only changes to the layer or map
definitions will be detected. For example change in the styling for the
layer. Changes to the actual data in Oracle will not be detected. 

	Traian

		-----Original Message----- 
		From: Butler, Juan P [mailto:jpbutler at co.pinellas.fl.us]

		Sent: Wed 8/2/2006 5:36 PM 
		To: users at mapguide.osgeo.org 
		Cc: 
		Subject: RE: [mapguide-users] Base Layers that are based
on Oracle Spatial data

		Well, I've been told that Enterprise handles the changes
to data that is stored in the repositories.  From my understanding, data
that is changed in the repositories will be marked in someway so that
the tiles can be rebuilt as needed.    Can someone from Autodesk please
clarify this? 

		Juan Butler - Senior Programmer/Analyst
		GIS Applications
		Pinellas County Information Systems
		jpbutler at pinellascounty.org

		Please note: All mail sent to and from Pinellas County
Government is subject to the Public Records Law of Florida.

  _____  

		From: Andy Morsell [mailto:amorsell at spatialgis.com] 
		Sent: Wednesday, August 02, 2006 5:30 PM
		To: users at mapguide.osgeo.org
		Subject: RE: [mapguide-users] Base Layers that are based
on Oracle Spatial data

		My understanding of the current functionality of base
layers is that they don't update themselves based on an underlying data
change regardless of the source data type.  This would be up to you to
delete the images from your TileCache directory to force them to rebuild
the next time somebody viewed that map area.

		Andy Morsell, P.E. 
		Spatial Integrators, Inc. 
		http://www.SpatialGIS.com 

  _____  

		From: Butler, Juan P [mailto:jpbutler at co.pinellas.fl.us]

		Sent: Wednesday, August 02, 2006 2:02 PM
		To: users at mapguide.osgeo.org
		Subject: [mapguide-users] Base Layers that are based on
Oracle Spatial data

		Does anyone at Autodesk (or anyone that has tested it
already) know if I use Oracle Spatial data for my base layers, will
Mapguide Enterprise know about the changes and update the tiles
accordingly?   I'm in the process of testing this and just wanted to
know if anyone has had any experience with it.

		Thanks.

		Juan Butler - Senior Programmer/Analyst
		GIS Applications
		Pinellas County Information Systems
		jpbutler at pinellascounty.org

		Please note: All mail sent to and from Pinellas County
Government is subject to the Public Records Law of Florida.

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