[GRASS-dev] Import PostGIS vector layer into SQLite database

[Markus Metz]

On Wed, Mar 27, 2019 at 5:42 PM Luí­s Moreira de Sousa <
luis.de.sousa at protonmail.ch> wrote:
>
> Hi all,
>
> I am working with vector layers (points) composed of more than 100 000
geometries. These layers are originally in a PostGis database and I import
them with v.in.ogr, using a formulation like:
>
> v.in.ogr \
>     input="PG:host=127.0.0.1 dbname=gisdb user=user password=secret" \
>     layer=schema.points \
>     output=points \
>     -o --overwrite
>
> This command is successful, however, operations with the resulting points
layer are remarkably slow. For instance, this layer must be later loaded in
R and that operation alone is taking over 3 hours.
>
> After some back-and-forth testing, I identified the problem: v.in.ogr is
not saving its output in the internal GRASS SQLite database. Knowing this,
I can create a copy of the original output, that is automatically inserted
into the SQLite database, e.g.:
>
> g.copy vector=points,points_mirror
>
> Importing the points_mirror layer to R takes 3 minutes instead of 3
hours, for instance.

Which GRASS version are you using? This should not happen with recent
versions of GRASS 7.4 and 7.6.

Markus M

>
> While mirroring vectors imported with v.in.ogr solves the issue, it is an
inelegant solution that also takes up unnecessary space. I would prefer to
instruct v.in.ogr somehow to force it to use the SQLite database. I could
not find any reference in the manual, is it possible to do?
>
> Thank you.
>
> --
> Luís Moreira de Sousa
> Email: luis.de.sousa at protonmail.ch
> RingID: ring:7ca91d83f4f9dec82fec9f1144b8e5c1ef2a110c
> URL: https://ldesousa.github.io
>
> Sent with ProtonMail Secure Email.
>
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