On 18th of December, Teodor Sigaev committed patch:
Introduce distance operators over cubes: <#> taxicab distance <-> euclidean distance <=> chebyshev distance Also add kNN support of those distances in GiST opclass. Author: Stas Kelvich
Continue reading Waiting for 9.6 – Cube extension kNN support
On 4th of December, Tom Lane committed really cool patch:
KNNGIST, otherwise known as order-by-operator support for GIST.
This commit represents a rather heavily editorialized version of Teodor's builtin_knngist_itself-0.8.2 and builtin_knngist_proc-0.8.1 patches. I redid the opclass API to add a separate Distance method instead of turning the Consistent method into an illogical mess, fixed some bit-rot in the rbtree interfaces, and generally worked over the code style and comments. There's still no non-code documentation to speak of, but I'll work on that separately. Some contrib-module changes are also yet to come (right now, point <-> point is the only KNN-ified operator). Teodor Sigaev and Tom Lane