Initialize kart on pre existing PostGIS database

[SrNetoChan]

Not sure if this is the right place to ask this.

Having a pre-existent database in PostgreSQL/PostGIS, already containing data is it possible to initialize a kart working copy in it and add only some of the pre-existing tables to kart versioning system?

Would that make sense?

I am looking for a convenient way to keep working normally in our PostGIS database, and use kart only on necessary tables.

[rcoup]

Yes, definitely makes sense.

Currently there's no way to convert a pre-existing table into a Kart table in place, but kart & non-kart tables can happily coexist in the same database — if you add the kart schema into your search path (eg: ALTER DATABASE mydb SET search_path TO "$user", public, kart;) then a query will find both kart & non-kart tables without needing the schema qualifier (first in search_path is preferred).

So, you can convert a table (mytable) that's in the public schema into a Kart table along these lines, if you don't have other related tables referring to fields in mytable. Practise this on a database copy first!

1. import mytable into the kart repository, so it gets checked out into your database as kart.mytable
2. alter the search path as above
3. drop the original mytable (public.mytable)
4. any queries referring to mytable will now use kart.mytable instead.

Related to #249

[marcathian]

Thank you very much. I was able to move on and create the postGIS repo and import data into it. However I am not able to load the data into a QGIS project using the QGIS plugin. I get the error when using both the GeoPackage and PostGIS working copy types. However the data is still loaded from the GeoPackage working copy type.

Kart_qgis_plugin_error-on_addToProject.txt

[pfw]

The error you are seeing in QGIS is a known one we are actively working on and should have a status update for you within the next few days.

[SrNetoChan]

For my specific user case, I needed to put my working copy on the public schema. I am failing to do it. Mostly because the schema to init kart needs to be empty. Then if I try to import data, it misses postgis. If I install postgis, it says the working copy is out of sync. Can any of you think of a way to use public as the kart working copy?

Thanks!!

[rcoup]

@SrNetoChan I'm keen to understand your requirement to use the public schema — what's the practical difference between that and doing ALTER DATABASE mydb SET search_path TO public,kart;? With that in place you can just do SELECT * FROM mykartdataset; the same way as you could if a table is in public.

wrt Postgis, you can install it in another schema too: CREATE EXTENSION postgis SCHEMA postgis;. You then might want ALTER DATABASE mydb SET search_path TO public,postgis;

📖 PostgreSQL docs on the schema search path

[SrNetoChan]

Well, I am working with a national (Portugal) data model that was created to store and share topographic cartography. Unfortunately, the data model was built around the public schema. All the qgis project and plugins are expecting the public schema. And once ready, the database of a particular location needs to be sent to the national cartographic authority for revision. If the tables are not in the public schema, it comes back saying it's not complying with data model.

Nevertheless, installing postgis in a separate schema might just work. I will let you know if it did!