[GRASS-dev] Vector file naming

[Glynn Clements]

Brad Douglas wrote:

> > > GRASS 6.3.cvs (hamilton2):/usr/src/grass6 > r.to.vect in=elizabeth.los
> > > out=elizabeth.los feature=area
> > > Illegal vector map name <elizabeth.los>. Character <.> not allowed.
> > > ERROR: Map name is not SQL compliant.
> > > 
> > > How do file names conflict with SQL92?  I thought SQL92 only applied to
> > > file contents.  Is this also being used as a workaround for DBF
> > > limitations?  What I'm getting at is: Why is '.' not allowed?  Doing a
> > > quick archive search failed to illuminate any light bulbs in the
> > > immediate vicinity.
> > 
> > Hi Brad,
> > 
> > AFAIK '.' is reserved for joins. '_' will work. 
> > 
> > See
> > http://grass.itc.it/grass63/manuals/html63_user/sql.html
> > -> NOTES
> > 
> > It would be nice to have the naiming constraints relaxed but
> > I am not sure if that's really possible.
> 
> '_' is also reserved for matching, so that can't be it.

No, _ is perfectly legal in column and table names. It is used as a
wildcard by LIKE, but it isn't significant anywhere else.

> Maybe a better question is: Why doesn't GRASS distinguish between tables
> and files (database)?

Because it isn't limited to the DBF driver.

> I would much prefer to have GRASS automatically
> substitute '_' for '.' in the table name so I can keep consistent naming
> conventions across rasters and vectors.

That could create a problem if you have both map.1 and map_1, as they
would both have the same name.

> It's a usability issue and somewhat annoying. :-)

FWIW, these issues were pointed out when the new vector architecture
was initially introduced. This isn't an oversight; it was a conscious
choice.

> I guess the real question is: How big of a job would this be?  Radim?
> If it isn't an overwhelming job, I'd like to propose it for 7.x.

It would appear to be a big enough job that Radim chose not to do it
when the issues were originally pointed out.

-- 
Glynn Clements <glynn at gclements.plus.com>