st_geometry VS RDS enable geodatabase

[Evan_mayday]

Can someone explain to me the difference between these two processes:

https://enterprise.arcgis.com/en/server/10.8/cloud/amazon/create-geodatabase-in-amazon-rds-for-postg...

https://desktop.arcgis.com/en/arcmap/latest/manage-data/databases/add-the-st-geometry-type-to-a-post...

Im running on AWS.  

Are functions such as st_point part of the postgis install and enable enterprise gdb?  I went thru all those steps outlined here on an RDS database, and cannot run functions such as st_point, st_transform, etc.

Alternatively I have a windows VM with postgres running on it, no postgis.  I DO have st_geometry.dll sitting wherever its supposed to be, and have 400+ sde_ and st_ functions available in postgres.

Should these two processes have the same end result? whats the difference?  

Thank you in advance,

E

[DavidHoy]

Hi Evan.

as you suspected, the st_ functions you are used to are actually part of the installation of the st_geometry type - which is an Esri creation and added manually with the st_geometry libraries (.dll in windows).
You cannot install the st_geometry.dll in RDS PostgreSQL as you cant get to the machine level.

What you are talking about is RDS PostgreSQL with PostGIS enabled. If you then enable the RDS database as a Geodatabase, you are adding the "sde" tables and the default type used for all spatial columns created using ArcGIS becomes PostGIS Geometry (and Geography is also available). This is not the same type as Esri supplied st_geometry which is not available in RDS.

PostGIS does provide a set of ST_ functions - but note PostgreSQL is always case sensitive - so perhaps try being strict with that.

[Evan_mayday]

Thank you for the reply!

follow up question-

does RDS + PostGIS get the same/similar toolsets/functions as Postgres + st_geometry?  and is there any functional difference between ESRI geometry and PostGIS geometry?  

Also, is there an ESRI docs page that outlines these difference?  

thankyouthankyouthankyouthankyou

E

[DavidHoy · Accepted solution]

Hi Evan,

I dont know of a comparison page, but...
There are a lot more ST_ functions provided by PostGIS than there are with the sde.st_ function set.
The ones with common names serve the same purpose (syntax may be different)

The Esri reference set is:
ST_Geometry SQL function reference 
and
https://desktop.arcgis.com/en/arcmap/latest/manage-data/using-sql-with-gdbs/a-quick-tour-of-sql-func...

PostGIS equivalent is:
https://postgis.net/docs/reference.html

hope this is somewhat useful

[Evan_mayday]

also, is there another workflow that i can follow to generate geometry points from a multiple tables each with lat/lngs?  (right now im creating a postgres SQL VIEW with UNION ALL on 10 separate tables)