On Mon, Jan 23, 2017 at 11:08 AM, Kased, Razy (Chemistry and
Geosciences) <rkased@monroecc.edu> wrote:
> I recently came across this question: "What is the purpose of PostGIS on
> PostgreSQL?" and wanted to know what this mailing list had to respond with.
PostGIS is a SQL wrapper to the GEOS library which lets you do a large
number of really complex things that relate to coordinate systems on a
precise level.
Postgres geo types are useful for a very small set of uses cases with
a small but important overlap with PostGIS: indexed bounded box
lookups which is a fairly common requirement.
All else being equal, less dependencies are good so if that's all you
need work off the built in types. If you need PostGIS though you
really need it. For example, I heavily use the ST_UNION aggregate
function to build large market boundaries from smaller zip code
boundaries and it works beautifully. There is no analog to that in
the built in stuff.
merlin