[postgis-users] PostGIS Raster for Met Data

[Sandro Santilli]

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