[UMN_MAPSERVER-USERS] Question re: PostGIS and MapScript getExtent() function

Daniel Morissette dmorissette at DMSOLUTIONS.CA
Wed Jul 13 11:26:23 EDT 2005

Paul Ramsey wrote:
> On 13-Jul-05, at 7:37 AM, Daniel Morissette wrote:
>> This being said, I remember working with Oracle Spatial a few years  
>> ago and being very disapointed that it didn't provide an easy way  to 
>> get accurate extents. I personally think this is a serious  limitation 
>> that any serious spatial database should fix...  hopefully postgis 
>> will take the lead and be the first spatial  database to do this right.
> I dunno, "select extent(geocolumn) from geotable" is pretty easy, and  
> completely accurate. Oh, you mean accurate *and* fast :)  

Opps... sorry... of course I meant accurate *and* fast.  :)

> Not only is it enough, it is what I do most of the time, so that my  WMS 
> capabilities have nice extents in them, instead of -Inf to Inf. 

That's all I needed to hear. ;)

>  How 
> about the ultimate punt: we error out when called and tell people  to 
> set their extents explicitly.

I wouldn't go that far. I think it's still better to offer good default 
values (the slow and accurate method that's currently in place) in all 
situations and document the fact that the user has the option to set 
their own extents to get better performance/accuracy.

  Daniel Morissette               dmorissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/

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