[GRASS-user] PostGIS import and primary keys

Juan Pedro Pérez Alcántara jp.perez.alcantara at gmail.com
Wed Oct 20 08:56:04 PDT 2021


I've been testing PostGIS to GRASS imports / exports and there are some
things I'm not sure I understand correctly. They are related to keeping
primary keys coming from PostGIS.

My table of origin at PostGIS has a primary key called gid_building
(integer). When using:

grass $GRASS_DB/PERMANENT --exec \
v.in.ogr --verbose --overwrite \
input="PG:host=$HOST dbname=cell_raw_data user=$USER port=$PORT password=
$PASS" \
layer=cat2020.building output=building \
snap=0.01 \
where="gid_building between 2633000 and 2633100"

and then exporting with:

grass $GRASS_DB/PERMANENT --exec \
v.out.ogr --overwrite \
input=building \
type=area \
output="PG:host=$HOST dbname=cell_raw_data user=$USER port=$PORT password=
$PASS" \
output_layer=cat2020_topo_clean.building_dump \
format=PostgreSQL \
lco=FID=gid_building_dump \

I found the following schema back in PostGIS:

gid_building_dump (integer, with a nextval sequence)
cat (integer)

But no trace of the original primary key in the PostGIS origin table
My guesses:

v.in.ogr just don't use the primary key of the original table,
gid_building. In
fact, if I drop the primary key from this column, it is imported normally.

GRASS add its cat field to store category.

v.out.ogr adds its own primary key with the nextval sequence.

I'm happy with GDAL / GRASS adding their own internal primary keys to the
in fact, I understand this is the sensible thing to do given the disparity
data models. My only question is: is there any way in v.in.ogr to keep the
primary key as a normal field?

Thanks a lot,


Juan Pedro Pérez Alcántara

jp.perez.alcantara at gmail.com
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