On Fri, Aug 30, 2019 at 6:28 AM Peter Geoghegan <p...@bowt.ie> wrote: > On Thu, Aug 29, 2019 at 8:22 PM Alexander Korotkov > <a.korot...@postgrespro.ru> wrote: > > Alternatively you can encode size in Z-value. But this increases > > dimensionality of space and decreases efficiency of join. Also, > > spatial join can be made using two indexes, even just current GiST > > without Z-values. We've prototyped that, see [1]. > > I'm pretty sure that spatial joins generally need two spatial indexes > (usually R-Trees). There seems to have been quite a lot of research in > it in the 1990s.
Sure, our prototype was an implementation of one of such papers. My point is that advantages of Z-value ordered GiST for spatial joins are not yet clear for me. Except faster build and smaller index, which are general advantages. ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
