Re: Cube extension kNN support

Documentation along with style fix.



> On 08 Feb 2015, at 00:32, Alexander Korotkov <aekorotkov@gmail.com> wrote:
>
> Hi!
>
> On Sat, Feb 7, 2015 at 12:45 PM, Stas Kelvich <stas.kelvich@gmail.com> wrote:
> I had updated old patch with kNN operators for cube data structures. Copying description from old message:
>
> Following distance operators introduced:
>
> <#> taxicab distance
> <->  euclidean distance
> <=> chebyshev distance
>
> For example:
> SELECT * FROM objects ORDER BY objects.coord <-> '(137,42,314)'::cube LIMIT 10;
>
> Also there is operator "->" for selecting ordered rows directly from index.
> This request selects rows ordered ascending by 3rd coordinate:
>
> SELECT * FROM objects ORDER BY objects.coord->3 LIMIT 10;
>
> For descendent ordering suggested syntax with minus before coordinate.
> This request selects rows ordered descending by 4th coordinate:
>
> SELECT * FROM objects ORDER BY objects.coord->-4 LIMIT 10;
>
> I've checked the patch. The first notes are so:
> 1) Check coding style, in particular braces. Postgres coding style require using it for multiline statements.
> 2) Update documentation according to new features.
>
> ------
> With best regards,
> Alexander Korotkov.