[Qgis-user] QGIS performance problem

[pcreso at pcreso.com]

Hi,

I have a PostGIS table & shapefile of the New Zealand coast (1:50,000)

If I open this table it plots in a fraction of a second, pretty much as expected, with similar speeds for both the shapefile & table.

However, if I zoom in, the redraw takes three minutes or more. 

While I'm waiting for the refresh, Qgis is showing 100% cpu load, postgres isn't showing at all (top). On an AMD dual core 3.2Ghz cpu with 8Gb ram it should not take anything like this long, and with earlier versions of Qgis (pre 1.0) it was much faster.

Performance is similar with both table & shapefile data sources, so it does not seem Postgres related.

However, plotting lines, points or polygons with tens of thousands of features rendered works well, it seems to primarily be polygons with many vertices (not even any holes) that are the problem.

OpenSuse 11.1, Qgis 1.2.0, Postgis table described below, only 3 features/records, indexed & vacuumed.


Does anyone have any idea what may be the issue?

I can provide an ssh login if anyone wants to test this for themselves.


Thanks,

   Brent Wood 






                                 Table "public.coast_poly"
 Column  |         Type          |                        Modifiers                         
---------+-----------------------+----------------------------------------------------------
 gid     | integer               | not null default nextval('coast_poly_gid_seq'::regclass)
 id      | bigint                |
 fid     | bigint                |
 name    | character varying(42) |
 geom_ll | geometry              |
Indexes:
    "coast_poly_pkey" PRIMARY KEY, btree (gid)
    "coast_poly_geom_ll_gist" gist (geom_ll)
Check constraints:
    "enforce_dims_geom_ll" CHECK (ndims(geom_ll) = 2)
    "enforce_geotype_geom_ll" CHECK (geometrytype(geom_ll) = 'MULTIPOLYGON'::text OR geom_ll IS NULL)
    "enforce_srid_geom_ll" CHECK (srid(geom_ll) = 4326)