[postgis-devel] Btree operators

Rémi Cura remi.cura at gmail.com
Thu Apr 7 10:01:44 PDT 2016


Under the hood bounding box equality seems like a very counter intuitive
behaviour.

On the other hand, adding a "::text" or "::bytea"in the "distinct on" part
does not feel like to much of a burden,
although it is mighty ugly.

Having a = operator with tolerance would be super useful, but I don't see
how you could use it in a distinct query.

Cheers,
Rémi-C

2016-04-07 17:13 GMT+02:00 Sandro Santilli <strk at keybit.net>:

> On Thu, Apr 07, 2016 at 03:06:56PM +0000, Komяpa wrote:
> > чт, 7 апр. 2016 г. в 17:39, Paul Ramsey <pramsey at cleverelephant.ca>:
> >
> > > Speed is a benefit. Once you start down the road of = semantics, the
> > > question of "which equals" looms large. Spatial equality?
> > > Representational equality? Equality within a tolerance? Doing a string
> > > compare is basically the only one that doesn't impose a surprising
> > > cost, and it is, as you say, noisy.
> >
> > The equality that is the same as string compare would be a lot less
> > surprising.
> > It shouldn't be slower than bbox equality with recheck for the case when
> > they're equal.
>
> We don't even need to convert to string, actually.
> A memcmp call would be pretty fast.
>
> --strk;
> _______________________________________________
> postgis-devel mailing list
> postgis-devel at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/postgis-devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-devel/attachments/20160407/a6f73cad/attachment.html>


More information about the postgis-devel mailing list