Re: index structure for 114-dimension vector

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

Andrew Lazarus <andrew(at)pillette(dot)com> writes:
> Because I know the 25 closest are going to be fairly close in each
> coordinate, I did try a multicolumn index on the last 6 columns and
> used a +/- 0.1 or 0.2 tolerance on each. (The 25 best are very probably inside
> that hypercube on the distribution of data in question.)

> This hypercube tended to have 10-20K records, and took at least 4
> seconds to retrieve. I was a little surprised by how long that took.
> So I'm wondering if my data representation is off the wall.

A multicolumn btree index isn't going to be helpful at all.  Jeff's idea
of using six single-column indexes with the above query might work,
though.

			regards, tom lane