[postgis-users] Inefficient query with QGIS?

[Aren Cambre]

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

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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