[GRASSLIST:10793] Re: How can I reduce the loading time of GRASS-layers in UMN Mapserver

[Radim Blazek]

On 3/7/06, wqual <wolfgang.qual at gmx.net> wrote:
> > DBF driver in GRASS creates copy of the table in memory.
> > Try to use Postgres and SQLite. Postgres library also loads
> > all results to memory  by default.
> I did not check Postgres, but using SQLite did not "produce" better results.
> Took about 12-13s to load the map.

Then I dont know you have to inspect better whole chain dbdriver-grass-ogr.

Radim

> > Unfortunattely GetFeature in OGR reads both geometry and
> > attributes even if the attributes are not required by application.
> >
> > Try also to compare time for GRASS and Shapefile if you use attributes
> > query.
> Indexed shapefile is still very fast, even when performing queries.
> >
> > BTW: Attribute queries are passed to GRASS database backend.
> And this means that ...?
> Do you think, it could be helpful to contact the UMN Mapserver list regarding
> this issue?
>
> Cheers,
>
> Wolfgang
>
> ---8<-----------------------
> >
> > Radim
> >
> > > > Also for testing to avoid the difference between nature
> > > > of topological and SF format try to test with points or lines.
> > >
> > > I did not test this by now.
> > >
> > > Best regards,
> > >
> > > Wolfgang
> > >
> > > ---8<-----------------
> > >
> > > > Radim
> > > >
> > > > On 3/6/06, Wolfgang Qual <Wolfgang.Qual at gmx.net> wrote:
> > > > > Dear list,
> > > > > I created a mapfile for two identical themes: One of them is a
> > > > > shapfile, the other one is a grass vector dataset. The shapefile
> > > > > contains a *.qix-file which was created using the program shptree.
> > > > > I compared the loading time for the two themes using the command
> > > > > "time wget -O /dev/null "http://path/to/the.map". Result: the grass
> > > > > theme took about 12 seconds (on a local machine), shapefile only 2s.
> > > > > My Question therefore: is there a possibility to speed up grass
> > > > > layers in the mapserver application (something like shptree does?)?
> > > > > The attribute table of the grass-theme is a (default) dbf-file.
> > > > >
> > > > > Declaration of the grass-layer in the mapfile:
> > > > >
> > > > > # OGR-Layer aus GRASS
> > > > > #_# START LAYER l8
> > > > > LAYER  NAME "l8"
> > > > > TYPE polygon
> > > > > STATUS ON
> > > > >     CONNECTIONTYPE OGR
> > > > >     CONNECTION
> > > > > "/home/wqual/grassdata/muenchen/stadtbezirk/vector/block/head"
> > > > >     DATA "1"
> > > > >     METADATA
> > > > >       LTITLE "l8"
> > > > >     END #metadata
> > > > > ### TYPE Polygon -- LEGTYPE 0x01 -- SYMTYPE 0x02
> > > > > ### singlepolyleg
> > > > >    CLASSITEM "cat"
> > > > >    CLASS NAME "Block_GRASS"
> > > > >     COLOR 255 0 0
> > > > >     OUTLINECOLOR 20 200 10
> > > > >    END #CLASS
> > > > > #_# LAYER l8 QUERY
> > > > > END # LAYER l8
> > > > >
> > > > > I would be very happy to receive some hints/tips on this issue.
> > > > >
> > > > > Best regards,
> > > > >
> > > > > Wolfgang
> > > > >
> > > > > --
> > > > > Echte DSL-Flatrate dauerhaft für 0,- Euro*!
> > > > > "Feel free" mit GMX DSL! http://www.gmx.net/de/go/dsl
>