FAQ When should I use geography over geometry

[robe]

Someone asked me this and it sounds like a question we will be getting often from both novices as well as existing users.

I was thinking in the geography side of things -- could whip up a feature matrix (an autogenerated one with some xsl voodoo magic that)

For each function that takes as input geography/geometry mark off whether it supports geometry/geography like with T meaning it uses a geometry transform operation so not native and yes/no being native or non-existent. We can put a special tag in each function description to easily pull the transform question out.

function geometry geography ST_Buffer yes T ST_Distance yes yes ST_DWithin yes yes

Then we need the descriptive FAQ of what geometry/geography offers from a performance/use case perspective I guess. E.g. support by third party tools and loaders etc. What range (are you dealing with regional or all over the world) -- etc.

So kind of like a questionaire type thing to consider before using one or the other.

[robe]

I guess we should also decide where this should go.

[pramsey]

Some content

[pramsey]

Here's some content to integrate and close this ticket with :)

[robe]

I might get to incorporating Paul's changes, but not this week. Though I'm not sure the best place in the manual for this.

I'll move back out if I have time before release.

[robe]

fixed at r5028 - r5030

Refer to:  http://www.postgis.org/documentation/manual-svn/ch04.html#PostGIS_Geography

and:

 http://www.postgis.org/documentation/manual-svn/ch03.html