Application Data

[Arnulf Christl]

Giridhar Manepalli wrote:
> Hello All,
> I would like to appreciate Bart who is on the list for helping me get
> in touch with some of the concepts of GIS and Mapserver.

Bart should be awarded something on the OpenGeoSpatial. Its a pity he is
not coming!

[...]
> Imagine that the above data is huge (as large as 100GB), so I need to
> dump this information to a database.

The sheer size of the data is not a problem for either PostgreSQL or
PostGIS. But as Stephen and Brent suggest it *is* a problem to try start
optimizing and tuning the database with the full load. Start as
suggested with smaller sections.

Be aware that when requesting such a large dataset it is important that
you know what functionality you want to use. We have learned a few weeks
ago that a feature request (WFS) can be a performance killer although
map requests (WMS) on the same MapServer and the database are perfectly
fast.

> I would like to know, how to use this data from a table to Map it onto
> a MAPServer.

One of many ways to do it:
- Upload CSV text file into the database
- Create new geometry column with AddGeometryColumn
- Write an SQL which combines and copies the x and y columns with
AddGeometryFromText into the new geometry column.
The SQL can be qute ugly depengding on how many intermediate steps you
need to put together the WKS string.

if the the col 'objgeom' (TEXT) contains values like: "(7.15 55.8)"
update test set the_geom = GeometryFromText('POINT '|| objgeom || '"', 4326)

if the the col 'objgeom' (TEXT) contains values like: "7.15 55.8"
without the brackets:
update test set the_geom = GeometryFromText('POINT ('|| objgeom || ')"',
4326)

Another way to do it:
Create a shape file from the data with somme other tool and load it into
PG/PostGIS using shp2pgsql.

***

I just saw that Jim already pointed you to all the docs. One more thing:
Never forget to create a GIST index on the geometry column and vacuum
analyze the database to make it take effect.

Best, Arnulf.

--
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Arnulf B. Christl
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http://www.ccgis.org
http://www.mapbender.org
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