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| Subject: | RE: [gislist] Topical ArcGIS and MS Access question |
| Date: |
06/22/2004 01:10:01 PM |
| From: |
Richard Nicoll |
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Hi Bill,
In a nutshell...
1 - If by 'large' GIS you are referring to data volumes, you are
probably aware that the PGDB has a 2GB file size limit. You could
always split your data across several mdb's, but this can cause problems
with updating and seamless datasets. If 'large' refers to users, the
PGDB is locked by the first person who opens it, thus forcing everyone
else to wait before accessing. One solution would be to use a
multi-user GDB format which negates both these hurdles - you dont need
ArcSDE if you use the Direct Connect option, but you do need a back-end
RDBMS (SQL Server is much cheaper than Oracle...). The other option if
you have lots of users but not many ArcGIS licences is to go
server/client, where clients use a browser plugin rather than the full
app. ESRI have just launched ArcGIS Server, or you can go with ArcIMS.
Otherwise you could explore the open source route if you are feeling
adventurous!
2 - The GDB is the latest development in ESRI GIS. They never intended
the shapefile format to be a permanent format and that's still in huge
use today! I think the GDB will continue to develop with more users
realising the benefits, and perhaps other vendors supporting it (see
ERDAS and Cadcorp...). On the RDBMS vs OODBMS side, this is not an
issue for the GDB model as it can be configured to run on any DBMS
(ArcSDE binary model), it is the front-end ArcGIS which dictates support
not the back-end. Essentially a GDB is just a bunch of tables
containing alpha-numeric data which nothing special, ArcGIS 'translates'
this into a GDB. If the DBMS supports something a bit better (like
Oracle Spatial features) then so much the better but it is not a
requirement. ESRI would need to support a new DBMS though with an
update.
3 - If the GDB model is supported in a future package, so much the
better. As a last resort, you can always export into the new package
via a commonly supported format such as shp/e00. I dont think future
migration of data should be an issue which prevents you using GDB right
now.
One last point - I am wondering whether you are aware that your
non-spatial data in the mdb can be stored as a table within the GDB
model, keeping all relationships? This would remove the need for the
ODBC link.
Regards,
Rich
-----Original Message-----
From: gislist-bounces@lists.geocomm.com
[mailto:gislist-bounces@lists.geocomm.com]On Behalf Of William Western
Sent: 17 June 2004 15:51
To: gislist@lists.thinkburst.com
Subject: [gislist] Topical ArcGIS and MS Access question
Hi Listers!,
Here's a topic that I would love to get your thoughts and ideas on...
I work for a Consulting company that specializes in Aquatic
Environments. Currently, myself and another fellow are developing a
substantial Information System to handle all environmental data (mostly
aquatic) that we collect in the field...fish, lower trophic/benthic,
water. MS Access is being used to store the bulk of the 'aspatial' data
(although ultimately everything in this is spatial), while the spatial
data (bathymetry, macrophytes beds, etc) is as you may have guessed
being stored in a Personal Geodatabase using ArcGIS 8.3. I use an ODBC
connection to bring the Access database into ArcGIS, and am capable of
performing joins, relates and queries on the Access database right in
ArcGIS. The spatial link between the two is provided by the Sampling
sites which contain a UID and coordinates (and several other data
fields), linking the tables in Access to a geographic location. Please
note that I'm working on a budget with the tools that I have. So far,
the system's interoperability is very good and I'm happy with it.
Here's some seed questions I hope you can 'run with':
(1) Interoperability - what are your thoughts on using connecting
these software tools to build a large GIS?
(2) The Future - Do you see the ESRI Geodatabase and MS Access
database becoming obsolete? (For example, if and when the Object
Oriented Databases take over and Relational Databases disappear)
(3) Migration - How do you foresee migrating datasets from these
packages into potential future packages?
Have a great day and thanks in advance,
Bill
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