On Thu, 9 Apr 2009 02:12:08 +0300, pablo platt <[email protected]> wrote: > Hi, > > I posted this question in the forum but I think that the list is more > active. > > PostGIS uses R-Tree index over GIST. > I'm trying to understand if it is possible to use couchDB for storing and > indexing the osm data. > couchdb is a schema less db for storing documents. Each document store data > encoded as JSON. > It uses B-Tree index so the only way I know to enable spatial index is to > use space-filling-curves (z-order, morton codes) > to translate a lat,lng to a number and then index all the numbers using a > B-Tree.
>From what I found out you usually do not use a Z-curve or Hilbert-Curve on a 1-dimensional index but you use it while constructing a never-to-be-changed 2D-tree. However I could not find any multi-dimensional trees that can do a rebalancing in O(1) like an AVL-tree can. So while this may be a good index for data-sets that never change it quickly becomes highly unbalanced in datasets that are changed frequently. I guess an R-Tree (also called 2D (R)ange-tree) was just easiest with the existing indexing datastructures they had and it provides adequate performance. Marcus _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
