[postgis-users] hierarchical topology and attributes at different levels

[William Kyngesburye]

I'm trying to figure out what I can do with hierarchical topology.  So far I understand (more or less) the construction of PostGIS topology and hierarchical topology, but I only have a vague conceptual idea of querying.

I have (want) a hierarchical organization of administrative areas: states (layer 3) and counties (layer 2).  Counties are a child layer of states, both are multipolygons grouped by the county or state.

I also have attributes for the minimum and maximum scale that individual faces can be displayed.  This is a child layer (layer 1) of counties.  ie, tiny coastal islands are not displayed at small scales.

Can the attributes of child layers be seen from a layer?  Or for my specific example, can I query for counties or states and only get the component faces (layer 1) where the query scale is within the min/max scale of the faces?  I guess it would be like a dynamic topogeometry that is a subset of the static defined topogeometry for the layer.

Maybe the query logic is backwards - instead, query the faces layer for the scale match, grouped by the parent layer of interest?  With the topological relationship nature of topology, would I even need a hierarchical setup for this reversed query?

-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/

The equator is so long, it could encircle the earth completely once.