[GRASSLIST:8511] Re: v.out.ogr - VERY slow!

Radim Blazek radim.blazek at gmail.com
Thu Oct 6 03:16:06 EDT 2005


On 10/6/05, Hamish <hamish_nospam at yahoo.com> wrote:
> > I'm running grass60. Linux. Need to export some layers to shp.  Having
> > used v.out.ogr in grass57 and found it to be quite fast, it is
> > painfully slow in 6.0, even for moderate sized files. E.g,:
> >
> > This took about 1/2 an hour!!
> >
> > -rw-r--r--  1 caumann caumann 43092713 Oct  5 13:21 neareasforest1.dbf
> > -rw-r--r--  1 caumann caumann      407 Oct  5 13:19 neareasforest1.prj
> > -rw-r--r--  1 caumann caumann 18240640 Oct  5 13:21 neareasforest1.shp
> > -rw-r--r--  1 caumann caumann    76908 Oct  5 13:21 neareasforest1.shx
> >
> > What gives?
>
>
> Probably you are exporting many large complicated polygon features?
>
> 1/2 and hour isn't bad. A week is bad. ;) Think of it as an enforced
> coffee break.
>
> You need to break up boundaries into smaller chunks (doesn't affect
> topology, just the way it is stored). GRASS 6.1-cvs has v.split which
> will do this for you.

He is talking about v.out.ogr, not v.in.ogr. I have already explained it here
http://grass.itc.it/pipermail/grass5/2005-July/018861.html
Temporary improvement is to use a database with index support
i.e. sqlite, pg, mysql.

Radim




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