On Thu, Jul 07, 2011 at 11:06:34PM +0000, Michael Akinde wrote: > Due to the number of grids I am somewhat leery of setting up (and tearing > down) multiple tables on an operational database (data grids change over > time). Keeping it in one table would presumably be better, assuming it is > practicable.
It is practicable to keep everything in one table, but if you never get items from mixed grids in the same spatial query you may give the optimizer better informations by keeping those grids in separate tables. For instance, querying for all items in a given bounding box might return X items from the lowest-resolution grid, X*2 from the next higher resolution, X*4 for the next and so on.... the estimator would think it's so many rows that an index scan is not worth the cost while indeed you may be just querying the lowest-resolution one. But it's just a guess, only you know the kind of queries you're going to run and how the planner deals with them. --strk; () Free GIS & Flash consultant/developer /\ http://strk.keybit.net/services.html _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
