[postgis-users] Data Versioning?

[Hubert Fröhlich]

We  have been practising versioning as we are forced to track back 
changes in land property map data into every detail.

We practise it on the database level. Every single object is stored with 
information on "creation" and "deletion", in fact "deletion" means only 
setting the object as "historical" and changing an attibute like 
"delete_date"

When retrieving data, we use SQL Statements like

"select attribute from table where ..... and delete_date > "today"::date 
( or something like that; don't care about my syntax errors..)

Using this way, we can even read differential data by using the date 
information in select statements.

However, we have been using this principle yet only for a PostgreSQL 
(with geometrical datatypes NOT from PostGIS) database and feed the 
results into our own applications which are not based on standard GIS 
products. We cared a lot about the design of the database table structure.

Works very well for our needs.

Greetings,

Hubert



>ArcSDE implements versioning at the server (read SDE software)  level.
>The database tier has no inherent "versioning" capability, regardless of
>whether it is running on Oracle, Informix or Brand X. Versioning is
>implemented using "delta" tables that track changes (adds and deletes)
>across versions. There are a slew of other tables (what I call "meta"
>tables) that make up the ArcSDE schema.
>
>My guess is that a middle tier would be required between
>PostgreSQL/PostGIS and the client to implement a versioning scheme
>similar to ArcSDE.
>
>-gary
>
>-----Original Message-----
>Subject: Re: [postgis-users] Data Versioning?
>
>
>SDE is ESRIs Spatial Database Engine.  It supports versioning for
>GeoSpatial data the same way that CVS does this for code.  CVS will not
>work for this purpose, as Spatial Data stored in PostGIS is not stored
>in flat text files like source code.  Postgres / PostGIS would need to
>support this directly.
>
>I don't have the answer to the question, but am also very interested to
>know if Postgres/PostGIS support any form of geospatial data versioning.
>I am also curious to know if it supports long transactions.  I should
>probably RTFM before asking though.
>
>--Craig
>
>
>
>----- Original Message ----- 
>From: "Rich Shepard" <rshepard at appl-ecosys.com>
>To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
>Sent: July 09, 2003 3:36 PM
>Subject: Re: [postgis-users] Data Versioning?
>
>
>  
>
>>On Wed, 9 Jul 2003, Jeff McKenna wrote:
>>
>>    
>>
>>>Pardon my beginner question, but I am trying to find out how 
>>>PostGIS/PostgreSQL handles data versioning.  Myself I am familiar 
>>>with SDE, but would love to find an open source alternative to 
>>>versioning
>>>      
>>>
>large
>  
>
>>>datasets.  Does PostGIS handle data versioning?  If not, are there 
>>>plans for this in the future?  Are there any documents/past email 
>>>postings regarding this?  Thanks.
>>>      
>>>
>>Jeff,
>>
>>  I've no idea what SDE might be, but there's always CVS. This is used
>>    
>>
>
>  
>
>>primarily for source code development projects, but I've used it for 
>>document development, too. So, I imagine that one could check in and 
>>out different data sets, too.
>>
>>Rich
>>
>>Dr. Richard B. Shepard, President
>>
>>                       Applied Ecosystem Services, Inc. (TM)
>>    
>>
>
>
>
>_______________________________________________
>postgis-users mailing list
>postgis-users at postgis.refractions.net
>http://postgis.refractions.net/mailman/listinfo/postgis-users
>  
>

-- 
-------------------------------------------------------------------------------
Dr.-Ing. Hubert Fröhlich			
Bezirksfinanzdirektion München 			
Alexandrastr. 3, D-80538 München, GERMANY
Tel. :+49 (0)89 / 2190 - 2980
Fax  :+49 (0)89 / 2190 - 2459
hubert.froehlich at bvv.bayern.de

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20030710/7a3b0afb/attachment.html>