knngist patch support

Hello,

I noticed this morning that the k nearest neighbor gist patch
https://commitfest.postgresql.org/action/patch_view?id=230 was still being
considered for inclusion in 9. Sadly, this feature appears to have been
dropped from 9.

It seems to me that the functionality this brings is one of the most common
use cases for mobile applications (or even web in some cases) that are
location enabled. How many times do we find ourselves "Finding the 10
nearest restaurants" in our smart phones? Well, this patch solves exactly
that in the most efficient manner.

Granted, one can currently solve this problem with PostgreSQL/PostGIS as it
stands, however the performance improvements that one can gain for those
types of (extremely common) queries leveraging the Gist enhancements are,
well, exciting.

300x time improvements? Sounds great to me.

I would love if you guys could consider applying this patch for this
upcoming release.

Best Regards,

- Ragi Burhum