[GRASS-user] speeding up v.clean for large datasets

Mark Wynter mark at dimensionaledge.com
Mon Apr 22 02:03:52 PDT 2013

Thanks Marcus.
Tried sqlite backend suggestion - no improvement  - then read that that sqlite is the default backend for grass7.
I suspect the complexity of the input dataset may be the contributing factor. For example, I ran v.clean over the already cleaned OSM dataset (2.6M lines), and it took only a few minutes since there were no intersections and no duplicates to remove.  

> Something is wrong there. Your dataset has 971074 roads, I tested with
> an OSM dataset with 2645287 roads, 2.7 times as many as in your
> dataset. Cleaning these 2645287 lines took me less than 15 minutes. I
> suspect a slow database backend (dbf). Try to use sqlite as database
> backend:
> db.connect driver=sqlite
> database=$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db
> Do not substitute the variables.
> HTH,
> Markus M

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