[postgis-users] Inefficient query with QGIS?

[Aren Cambre]

Thanks. Would you recommend QGIS do that instead of the expensive query on
the view?

BTW, turns out there was a QGIS option to limit the expensive query to 100
rows, but it was kind of buried.

On Sun, Jan 30, 2011 at 11:40 PM, Bruno Friedmann <bruno at ioda-net.ch> wrote:

> On 01/30/2011 09:43 PM, Aren Cambre wrote:
> > Discussing with a developer, it turns out there's an option named *Use
> > estimated table metadata* in the PostGIS connection properties. Using
> that
> > solved it for me as it adds *LIMIT 100* to the query.
> >
> > So the fix is there, it's just kind of buried.
> >
> > And, again, this is for a view, and it appears there's no way to know
> what a
> > kind of geometry is in a view's geometry column without inspecting it.
> >
> > Aren
>
> Aren, on recent postgis, >1.5x if you issue the select
> populate_geometry_columns() it take care of views too.
>
> >
> > On Sun, Jan 30, 2011 at 2:03 PM, Ivan Mincik <ivan.mincik at gmail.com>
> wrote:
> >
> >> On Sun, Jan 30, 2011 at 4:59 PM, Aren Cambre <aren at arencambre.com>
> wrote:
> >>> I noticed this really inefficient query when QGIS was importing a
> Postgis
> >>> layer:
> >>> select distinct case when geometrytype("the_geom") IN
> >> ('POINT','MULTIPOINT')
> >>> THEN 'POINT' when geometrytype("the_geom") IN
> >>> ('LINESTRING','MULTILINESTRING') THEN 'LINESTRING' when
> >>> geometrytype("the_geom") IN ('POLYGON','MULTIPOLYGON') THEN 'POLYGON'
> end
> >>> from [databaseGoesHere]
> >>> That surprised me because QGIS should already know the geometrytype
> >> through
> >>> the geomerty_columns table.
> >>> Is this really QGIS's fault, or did Postgis cause/require this? Want to
> >> make
> >>> sure before I file a bug report.
> >>
> >> Hi, which QGIS version do You use ?
> >> Has all You tables and views valid records in 'geometry_columns' ? If
> >> not, tables/views which are not present in 'geometry_colums' are
> >> queried by query You are talking about. If just one of them is big, or
> >> time expensive view, each database connect will take very long time.
> >>
> >> In current trunk (and I do not remember how many versions back), there
> >> is option 'Only look in the geometry_columns tables' which can help
> >> You.
> >>
> >> Ivan
> >> _______________________________________________
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> >>
> >
> >
> >
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>
> --
>
> Bruno Friedmann
> Ioda-Net Sàrl www.ioda-net.ch
>
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