Your data statement is needlessly complicated, which is creating more
convoluted SQL than you need at the backend, but generally the
planner optimizes these things away. You could try
layer->set("data","the_geom FROM south_america_large USING UNIQUE
gid USING SRID=-1");
I doubt it will help much. Check your postgresql statement log (you
will have to turn on statement loggin) and plug the query into psql
to see what the SQL EXPLAIN shows.
P
On 18-Apr-06, at 9:42 AM, Bertsch wrote:
Hi List,
As I was reading in the PostGIS manual a GIST index on the geometry
column
will speed up the application in several cases.
So i was creating an index on my south_america_large table with
CREATE INDEX
south_america_large_index ON south_america_large USING GIST(the_geom
GIST_GEOMETRY_OPS); VACUUM ANALYZE;
Code:
layer->set("data","the_geom FROM (SELECT the_geom,gid FROM
south_america_large) AS myquery USING UNIQUE GID USING SRID=-1");
map->setExtent(-54,-20,-39,-9); the extension of this map is
(-117,-56) -
(-34,32)
When i run the application i get the same time using the database
with GIST
or using it without GIST. Furthermore i was trying the same with a
shape
file and a quadtree index and i got better results for the
shapefile with
the quadtree index. Maybe someone can help me.
Thanks,
Clemens
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