Re: [PERFORM] index structure for 114-dimension vector

2007-04-20 Thread Tom Lane
Andrew Lazarus <[EMAIL PROTECTED]> 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

Re: [PERFORM] index structure for 114-dimension vector

2007-04-20 Thread Mark Kirkwood
Andrew Lazarus wrote: 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.) Thi

Re: [PERFORM] index structure for 114-dimension vector

2007-04-20 Thread Andrew Lazarus
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 ha

Re: [PERFORM] index structure for 114-dimension vector

2007-04-20 Thread Mark Kirkwood
Jeff Davis wrote: On Fri, 2007-04-20 at 12:07 -0700, Andrew Lazarus wrote: I have a table with 2.5 million real[] arrays. (They are points in a time series.) Given a new array X, I'd like to find, say, the 25 closest to X in some sense--for simplification, let's just say in the usual vector norm

Re: [PERFORM] index structure for 114-dimension vector

2007-04-20 Thread Jeff Davis
On Fri, 2007-04-20 at 12:07 -0700, Andrew Lazarus wrote: > I have a table with 2.5 million real[] arrays. (They are points in a > time series.) Given a new array X, I'd like to find, say, the 25 > closest to X in some sense--for simplification, let's just say in the > usual vector norm. Speed is cr

[PERFORM] index structure for 114-dimension vector

2007-04-20 Thread Andrew Lazarus
I have a table with 2.5 million real[] arrays. (They are points in a time series.) Given a new array X, I'd like to find, say, the 25 closest to X in some sense--for simplification, let's just say in the usual vector norm. Speed is critical here, and everything I have tried has been too slow. I im