[GRASS-user] Help with defining DB Drivers for input and outputs

[Mark Wynter]

Within the same mapset, is it possible to specify SQLITE as the database for the output layer, whilst using a map as an input that has a PG driver?

I’ve read the manual and tried a few approaches, but I found the outputs still get written to PG.  May be I’ve missed a critical step?  See messages below. I also experimented with v.add.table and v.add.columns to the empty map, to no avail.

I want the outputs written to sqlite, because v.out.ogr and v.out.postgis when the attributes are stored in PostgreSQL seems unworkably slow (which may be a pg_conf issue but my DB is performing well at scale for non-GRASS parallelised workflows)?

I want to keep the input attributes still in PostgreSQL because its the road table, and the fwdcost and bwdcost columns get updated by data from non-GRASS schema.

I need the fastest pipeline performance possible for when I scale the solution out (which will be done using GNU Parallel).  

Right now I’m stuck between a rock and a hard place.

Really hoping someone can help me out…  :-)

Thanks
Mark

#CREATE EMPTY MAP TO HOLD THE OUTPUTS
g.remove -f type=vector pattern="temp**"
layername="temp_8
v.edit --overwrite tool=create map=$layername
v.db.connect map=$layername table=$layername driver=sqlite  database='$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db’
v.info $layername

#RUN THE ANALYSIS, WHERE THE INPUT LAYER ATTRIBUTES RESIDE IN POSTGRESQL
v.net.allpairs  --overwrite in=nsw_road_network_final_connected cats=1-100  out=$layername afcolumn=fwdcost abcolumn=bwdcost

# NO GOOD - THE OUTPUT ATTRIBUTE TABLE STILL APPEARS IN PGL 

##########################
GRASS 7.0.0svn (nodeclean):~ > v.edit --overwrite tool=create map=$layername
Building topology for vector map <temp_8 at PERMANENT>...
Registering primitives...
0 primitives registered
0 vertices registered
Building areas...
0 areas built
0 isles built
Attaching islands...
Attaching centroids...
Number of nodes: 0
Number of primitives: 0
Number of points: 0
Number of lines: 0
Number of boundaries: 0
Number of centroids: 0
Number of areas: 0
Number of isles: 0
v.edit complete.
GRASS 7.0.0svn (nodeclean):~ > v.db.connect map=$layername table=$layername driver=sqlite  database='$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db'
WARNING: Table <temp_8> does not exist in database
         <$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db>
The table <temp_8> is now part of vector map <temp_8> and may be deleted or
overwritten by GRASS modules
DBMI-SQLite driver error:
Unable to create index:
create unique index  if not exists temp_8_cat on temp_8 ( cat )
no such table: main.temp_8

DBMI-SQLite driver error:
Unable to create index:
create unique index  if not exists temp_8_cat on temp_8 ( cat )
no such table: main.temp_8

WARNING: Cannot create index
Select privileges were granted on the table
GRASS 7.0.0svn (nodeclean):~ > v.db.connect -p map=$layername
Vector map <temp_8> is connected by:
layer <1/temp_8> table <temp_8> in database </var/tmp/nodeclean/PERMANENT/sqlite/sqlite.db> through driver <sqlite> with key <cat>
GRASS 7.0.0svn (nodeclean):~ > v.info $layername

 +----------------------------------------------------------------------------+
 | Name:            temp_8                                                    |
 | Mapset:          PERMANENT                                                 |
 | Location:        nodeclean                                                 |
 | Database:        /var/tmp                                                  |
 | Title:                                                                     |
 | Map scale:       1:1                                                       |
 | Name of creator: root                                                      |
 | Organization:                                                              |
 | Source date:     Wed Feb 11 22:49:13 2015                                  |
 | Timestamp (first layer): none                                              |
 |----------------------------------------------------------------------------|
 | Map format:      native                                                    |
 |----------------------------------------------------------------------------|
 |   Type of map: vector (level: 2)                                           |
 |                                                                            |
 |   Number of points:       0               Number of centroids:  0          |
 |   Number of lines:        0               Number of boundaries: 0          |
 |   Number of areas:        0               Number of islands:    0          |
 |                                                                            |
 |   Map is 3D:              No                                               |
 |   Number of dblinks:      1                                                |
 |                                                                            |
 |   Projection: Albers Equal Area                                            |
 |                                                                            |
 |               N:                 0    S:                 0                 |
 |               E:                 0    W:                 0                 |
 |                                                                            |
 |   Digitization threshold: 0                                                |
 |   Comment:                                                                 |
 |                                                                            |
 +----------------------------------------------------------------------------+

GRASS 7.0.0svn (nodeclean):~ > v.net.allpairs  --overwrite in=nsw_road_network_final_connected cats=1-100  out=$layername afcolumn=fwdcost abcolumn=bwdcost
WARNING: Vector map <temp_8> already exists and will be overwritten
WARNING: Table <temp_8> linked to vector map <temp_8> does not exist
Building graph…

#### Outputs of temp_8 visible in PostgreSQL….#########

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