Connecting to PostGIS with ArcGIS
PostGIS is a new alternative way to store datalayers, and fills a similar role to a directory containing shapefiles and/or coverages, an MS Access-based personal geodatabase, a file geodatabase, ArcSDE, Oracle Spatial, etc. In this case, the data resides in a PostgreSQL database. PostgreSQL is a database that is commonly used for web applications, similar to MySQL. Storing the information in a database rather than a bunch of files has a lot of advantages. The databases like PostgreSQL, MySQL, Oracle, etc. are referred to as RDBMS’s: Relational Database Management Software. This article (from ESRI’s ArcGIS help file) explains a bit about why it makes a lot of sense to store your GIS data in a database: A Short History Lesson on Simple Features in GIS.
A few of the advantages to using a database on a server:
- easier to share
- single version of data makes it easier to maintain, backup
- multiple people can access/edit (even at the same time)
- can connect with the data source in other ways (SQL queries, web pages, programs)
Disadvantages:
- slower load times
- what happens when you don’t have internet?
- extra overhead; time to set up and configure
- expertise in managing databases required
The main reason I am interested is to be able to use the free, open-source program for calculating routes, pgRouting, which is designed to work with PostGIS.
Unfortunately, it doesn’t look like this is possible to do for low cost. ESRI recently added support for PostGIS to ArcGIS version 9.3. It looks like you need the ArcGIS Server Enterprise software, which I do not have, and don’t have any intention of getting. According to the information on this manual page Using the PostGIS Geometry Type, it looks like ArcGIS is also quite picky about which specific version of PostgreSQL and PostGIS you can work with.
There is also a third-party extension called ZigGIS that lets you work with PostGIS data right from ArcMap. It was free for a while, but now it costs $279. It looks like nice software, but is not really useful for a project with a budget of $0. It looks like the developer makes the source code available for personal and educational use. The project is in Visual C# .NET, and I don’t really have the software or the skillset to compile these and make the program work.
My conclusion is that the OSGEO combination of qGIS/GRASS is probably the way to go, instead of wasting time or money trying to get ArcGIS to connect to PostGIS.