"GIS-databases" are databases that have geometry types, so next to the standard things such as integer, float, you can store stuff as polygon, line, etc... Of course you could build geometry using relational tables of just floats (for the coordinates) and some people have, but having specialised spatial data types greatly optimises working with them, these spatial databases then also implement "natively" spatial indices and spatial functions (eg. "is this point inside this polygon"). MySQL and PostGIS both implement a standardised form of spatial data types (by theOpenGeospatial Consortium: http://www.opengeospatial.org/ <http://www.opengis.org> ). The main differernce is that PostGIS has tis standard implemented almost complete, while MySQL still misses some parts. The main missing part is the SRID or Spatial reference system support. That means that data in MySQL will have to be in a fixed refrenece system, whereas in PostGIS you can mix data in different ref.systems and even recalculate data into another ref.sys. If you can do without that, MySQL is as good as PostGIS (and maybe better, because it's much simpler to use and in my opinion has much better administration tools). But if you need the missing parts, you'll use PostGIS. BTW, both implement the OpenGeoSpatials "Simple Feature Specification for SQL", so you can very simply change your app to talk to either (or both) of them... ____________________________ Barend Köbben International Institute for Geo-information Sciences and Earth Observation (ITC) PO Box 6, 7500AA Enschede (The Netherlands) ph: +31-(0)534874253; fax: +31-(0)534874335 _____________________________
________________________________ From: [email protected] on behalf of Omar Abo-Namous Sent: Sun 10/30/05 12:30 To: [email protected] Subject: Re: [svg-developers] Best GIS database? Hi, what exactly is sepcial about GIS-databases?? Could someone hint me to a page with some explanations? thnx Omar tbone58x wrote: > I am guessing the open source answer is PostGIS (part of Postgres) but > it appears that MySQL is much more popular than Postgres. Does MySQL > support GIS like Postgres? > > > > > > > ----- > To unsubscribe send a message to: [EMAIL PROTECTED] > -or- > visit http://groups.yahoo.com/group/svg-developers and click "edit my > membership" > ---- > Yahoo! Groups Links > > > > > > > ----- To unsubscribe send a message to: [EMAIL PROTECTED] -or- visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" ---- Yahoo! Groups Links [Non-text portions of this message have been removed] ------------------------ Yahoo! Groups Sponsor --------------------~--> Get Bzzzy! (real tools to help you find a job). Welcome to the Sweet Life. http://us.click.yahoo.com/A77XvD/vlQLAA/TtwFAA/1U_rlB/TM --------------------------------------------------------------------~-> ----- To unsubscribe send a message to: [EMAIL PROTECTED] -or- visit http://groups.yahoo.com/group/svg-developers and click "edit my membership" ---- Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/svg-developers/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
