[GRASS-user] Re: Export vect to shapefiles

[Moritz Lennert]

On 28/10/08 17:13, Milton Cezar Ribeiro wrote:
> Dear Markus,
> 
> Thank your for your reply.
> I agree completely with you. But I can handle a file with almost 
> 4.500.000 polygons (=area?) on ArcGis. Have you any suggestion of how 
> can I skipt this trouble?

Do you have access to an equivalent (in terms of hardware) GNU/Linux box 
to test whether you see the same issue ?

You could also detach the attribute table from the map (v.db.connect -d) 
and see if this solves the problem.

For your info: on my GNU/Linux box exporting 20,000 polygons with 
attributes takes about 3 minutes, but without attributes only 5 seconds 
and 120,000 polygons without attributes 15s. So, most of the time seems 
to be spent with writing the dbf file.

[some testing...]

Actually it's mainly reading the dbf file that takes time. If I put the 
(20,000 polygon) attribute data into an sqlite database, export "only" 
takes 53s and with postgres 1min26s. Whereas with a dbf attribute table, 
export takes roughly the same time whatever the format (tried GML, DGN, 
MapInfo - but the latter also uses dbf if I'm not mistaken.)

And I seem to remember that there were some issues with the DBF driver 
in windows.


Moritz


> 
> Best wishes,
> 
> miltinho
> 
> 
>     2008/10/28 Markus Neteler <neteler at osgeo.org <mailto:neteler at osgeo.org>>
> 
>         miltinho,
> 
>         remember the 100000 areas - a non-trivial size.
> 
>         Markus
> 
>         On Tue, Oct 28, 2008 at 3:51 PM, Milton Cezar Ribeiro
>         <miltinho.astronauta at gmail.com
>         <mailto:miltinho.astronauta at gmail.com>> wrote:
>          > Hi GRASS-gurus,
>          > I tryed the command again, using the GRASS MSYS console, and
>         I noticed that
>          > when my output command reach what I think is the "end" of
>         task, the GRASS
>          > don´t finish it. So, The command appear stay in loop, and it
>         never finish.
>          > And if I copy the files and try to open it on ArgGis - I
>         really need it :-(
>          >   - the ArcGis don´t understand the format.
>          > Any suggestion?
>          > miltinho
>          > brazil
>          >
>          > 2008/10/28 Milton Cezar Ribeiro
>         <miltinho.astronauta at gmail.com
>         <mailto:miltinho.astronauta at gmail.com>>
>          >>
>          >> Dear All,
>          >> I am running native WinGrass and I am trying
>          >> to export a vector map (with 100.000 areas).
>          >> The command below is what I am using.
>          >> v.out.ogr input=myvect dsn=c:/temp olayer=myexport type=area
>          >> But after a all nigth long the command not finish
>          >> and now update is done on the output files (which
>          >> have about 80MB) since after 20minutes I start the command.
>          >> Any help are welcome.
>          >> Best wishes,
>          >> miltinho astronauta
>          >> brazil
>          >
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> 
> 
> 
>         --
>         Open Source Geospatial Foundation
>         http://www.osgeo.org/
>         http://www.grassbook.org/
> 
> 
> 
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