On 4/28/2012 8:44 AM, Matt McClelland wrote:
Hi All
I have a set of contours in a SHP file
If I point my map file to the SHP file I can generate a WMS image in
under 1 second
Shp file is just shy of 200MB
I then use shp2pgsql to load the same dataset into the DB
I added an index for the_geom
And am requesting the data in the mapfile using the same EPSG
The map draws correclty but is now taking about 30secs when using the DB.
Any ideas on how to make it faster.
Simplify the data for the that zoom level.
If you are all the way zoomed out and drawing all the data, then the
shapefile will be fastest. An index does not help if you are drawing all
the data as you need to do a full table scan anyway to get all the
records. It is simply faster to read 200MB from disk than from the
database because the database has to fetch the same data and may have to
jump through some hoops to get it out of extended storage, then it has
to encode the data and send it over the connection and the client has to
decode the data.
Do you really need all the resolution of the data at this scale? If not
create another column and simplify the geometry into that column and set
up your mapfile to query the simplified data at this zoom and to query
the detailed data as you zoom in.
-Steve W
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