I do not know about GeoReduceGeometry but one way to use the Australian postcodes is to use IdevioMaps (se http://bi.idevio.com). There Australian postcode are included in the product, simplified and ready to use. You do not even need to load the areas but use the postcodes as the dimension in an AreaLayer and it will automatically find the areas and display them for you (under Location Settings, set that you mean postal areas and country is Australia).
One note about simplification is that to get a good result you need to do the simplifications topologically, not one area at a time. Otherwise you will generally get gaps and overlaps between areas.
Drop a message to firstname.lastname@example.org to get an evaluation license.
the GeoReduceGeometry function is an aggregating function, so you need to use a Group By when you use it in the load script, otherwise you get the Invalid Expression error.
Additionally, there is a second parameter to set the level of reduction, between 0 to 1, with 0 = no reduction and 1 = maximal reduction.
I'll see about improving the help for the geospatial function topics to include examples.
(kml, Table is [World.shp/Features]);
LOAD world.Name, GeoReduceGeometry(world.Area,0.5) as [Area] resident Map Group By world.Name;
Can you try this:
"Aus Postcode Boundaries 2015.Name",
"Aus Postcode Boundaries 2015.Point",
"Aus Postcode Boundaries 2015.Area"
FROM [lib://desktop/Aus Postcode Boundaries 2015.kml]
(kml, Table is [POA_2011_AUST_2013_11_26_14_20.kmz/POA_2011_AUST_2013_11_26_14_20.KML]);
LOAD "Aus Postcode Boundaries 2015.Name",
GeoReduceGeometry("Aus Postcode Boundaries 2015.Area",0.9) as [Area]
Group By "Aus Postcode Boundaries 2015.Name";
drop table aus_temp_map;