John, On 10/31/06 8:29 PM, "Tom Lane" <tgl@xxxxxxxxxxxxx> wrote: >> 'chrX' and StartPosition > 1000500 and EndPosition < 2000000; > > Also, there's the PostGIS stuff, though it might be overkill for what > you want. Oops - I missed the point earlier. Start and End are separate attributes so this is like an unbounded window in a Start,End space. PostGis provides quadtree indexing would provide a terse TID list but you still have the problem of how to ensure that the heap tuples being scanned are efficiently retrieved, which would only happen if they are grouped similarly to the retrieval pattern, right? - Luke