[GRASS-user] Database advice
rsbhalla at gmail.com
Mon Dec 3 08:19:41 PST 2012
Thanks for your inputs Markus,
Yes, as you predicted, there are some locking issues in Q-GIS if the
same table is accessed, but not otherwise (I use linux).
Also specifying a single database was simple enough in db.connect
<db.connect driver=sqlite database=$GISDBASE/$LOCATION_NAME/db.sqlite>.
However table names have to be unique. This is obvious and I should have
tried this earlier, sorry.
On 12/03/2012 06:13 PM, Markus Neteler wrote:
> On Sat, Nov 24, 2012 at 4:52 PM, R.S. Bhalla <rsbhalla at gmail.com> wrote:
>> Dear list,
>> I go back and forth between GRASS and QGIS for a recent assignment. I'm
>> considering dumping all my GRASS vector attributes to the same table created
>> by SpatiaLite (my default vector back-end for QGIS) so that I can query
>> attributes easily, irrespective of GIS. My questions are:
>> 1. Will there be serious performance penalties for doing this?
> Do you mean to have one SQLite DB? There may be some locking issue
> on Windows but perhaps it does not apply here.
>> 2. Is there a way to specify a single database, regardless of mapset,
>> in GRASS or do I need to do this separately for each mapset?
> Commonly there is one SQLite DB per mapset.
> With db.connect the settings could be changed. But note that you can only
> write in the current mapset (I suppose that also applies to the DB backend).
> The best would be of course to try out and report.
>> I am presently keeping the databases separate and attaching them as schemas
>> for queries, which I figure is the "conventional" way of doing things.
> It depends: SQlite is a file based, no overhead DB and not a server. If
> stored in a SQL based server this may fully apply.
>> However if I do so, I need to stick to front-ends which support schemas.
>> Thanks in advance for your suggestions.
> Maybe other list members have more experience here than me.
R.S. Bhalla, Ph.D.
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