[GRASS-user] Use of Postgres/PostGIS with GRASS

   I'm starting a couple of large modeling/analytical projects and believe
it's time I understood when and how to store data in postgres and when to
use postgis. For the past dozen or so years I've applied GRASS to projects
all data have resided in the internal data formats. This is new territory
for me and I'd like to do it right from the beginning.

   My base data sets (statewide) include a postgres table with 110,852 rows
holding water well log data, and a set of (soon-to-be-imported)
hydrography/hydrologic units .shp files with associated .dbf attribute
tables.

   When it is appropriate to put all attribute data in postgres tables and
associate GRASS with those?

   When is it advisable to use postgis?

Rich

Rich wrote:

When it is appropriate to put all attribute data in
postgres tables and associate GRASS with those?

When is it advisable to use postgis?

my guess is that postgis would be better once you get to more
than 1-3 million vector data points and grass's vector engine
memory requirements get too much.

unless of course you were hoping to learn more about postgis,
in which case this sounds like a good opportunity.

Hamish

On Thu, 24 Feb 2011, Hamish wrote:

my guess is that postgis would be better once you get to more than 1-3
million vector data points and grass's vector engine memory requirements
get too much.

Hamish,

   Ah, so. Good to know. I hope no project of mine has a single table with
that many vector nodes.

unless of course you were hoping to learn more about postgis, in which
case this sounds like a good opportunity.

   I'm not in this for fun, so if I don't need to learn postgis I won't.

   Guess I need to look at the v.db.* modules to learn how to have GRASS see
the well log data in the postgres table and import them to the project
directory.

Many thanks,

Rich

Wait, so GRASS can read directly from PostGIS tables? I thought you had to import all the data into GRASS first?

Aren

On Thu, Feb 24, 2011 at 5:42 PM, Hamish <hamish_b@yahoo.com> wrote:

Rich wrote:

When it is appropriate to put all attribute data in
postgres tables and associate GRASS with those?

When is it advisable to use postgis?

my guess is that postgis would be better once you get to more
than 1-3 million vector data points and grass’s vector engine
memory requirements get too much.

unless of course you were hoping to learn more about postgis,
in which case this sounds like a good opportunity.

Hamish


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