On Sun, May 23, 2010 at 12:23:27AM +0200, Frederik Ramm wrote: > Hi, > > David Carmean wrote: > > Who/what uses the ways.bbox column? Is there something/somebody > > that cannot use the linestring gist index, but instead requires > > an explicit bounding box geometry? > > Is the bbox column not meant to be a quicker alternative to a full > linestring (quicker in importing, not quicker in using)? I.e. you won't > have a linestring to base your GIST index on if you use that as intended.
The presence of the gist index on the linestring geometry column is what allows the GIS client I use to link only a small portion of the dataset based on a bounding box I specify; without it, it links the entire table as a drawing layer. The gist index presents a "proxy" bounding box internally. http://postgis.refractions.net/documentation/manual-1.3/ch03.html#id2570609 As described above, this index can be used to perform a quick first-pass query based on just the table indices (proxy bounding boxes) and present the main query with a pre-filtered set of candidates. I'm just wondering if there's some other application that uses this explicitly-built bbox geometry column (and whether it could be improved by using the index instead). _______________________________________________ osmosis-dev mailing list osmosis-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/osmosis-dev
