[postgis-users] flow direction (pointer) indexing

[Robert W. Burgholzer]

I am interested in an indexing scheme that will order line segments and 
polyogn "cells" by a flow network, for the purposes of optimizing hydrologic 
models done uysing postgis.

I will n ow ramble, and brainstorm in this email, so please excuse if what I 
say seems non-pertinent.

Perhaps this is not even necessary, I could establish some sort of "pointer" 
system as a column entry, pointing to the next cell along the flow path, but I 
am thinking that perhaps there exists some sort of indexing schema trhat will 
accomp[lish this, thus yielding something native to tthe database, something 
fast, and something easy to update.

My notion is that indexes of features that are "connected" could be kept 
inside the database.

Does anyone know of a technique which exists for this type of thing, or a way 
to implement current indexing schemes?

I presume this is not unique to hydrological modeling, people who work in any 
type of least cost routing endeavors must have techniques for handling this 
type of thing.

ANy suggestions would be appreciated.

robert