Re: index structure for 114-dimension vector

From: Tom Lane
Subject: Re: index structure for 114-dimension vector
Date: ,
Msg-id: 3357.1177116271@sss.pgh.pa.us
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In response to: Re: index structure for 114-dimension vector  (Andrew Lazarus)
List: pgsql-performance

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Basic Q on superfluous primary keys  ("Kynn Jones", )
 Re: Basic Q on superfluous primary keys  (Bill Moran, )
  Re: Basic Q on superfluous primary keys  ("Merlin Moncure", )
   Re: Basic Q on superfluous primary keys  ("Craig A. James", )
    Re: Basic Q on superfluous primary keys  ("Merlin Moncure", )
     Re: Basic Q on superfluous primary keys  (Greg Smith, )
      Re: Basic Q on superfluous primary keys  ("Merlin Moncure", )
       Re: Basic Q on superfluous primary keys  ("Craig A. James", )
        Re: Basic Q on superfluous primary keys  (Richard Huxton, )
         Re: Basic Q on superfluous primary keys  (Greg Smith, )
        Re: Basic Q on superfluous primary keys  ("Merlin Moncure", )
         Re: Basic Q on superfluous primary keys  ("Craig A. James", )
        Re: Basic Q on superfluous primary keys  (Jeff Davis, )
       Re: Basic Q on superfluous primary keys  ("Dave Dutcher", )
        Re: Basic Q on superfluous primary keys  ("Merlin Moncure", )
         index structure for 114-dimension vector  (Andrew Lazarus, )
          Re: index structure for 114-dimension vector  (Jeff Davis, )
           Re: index structure for 114-dimension vector  (Mark Kirkwood, )
            Re: index structure for 114-dimension vector  (Andrew Lazarus, )
             Re: index structure for 114-dimension vector  (Mark Kirkwood, )
             Re: index structure for 114-dimension vector  (Tom Lane, )
            Re: index structure for 114-dimension vector  (Arjen van der Meijden, )
          Re: index structure for 114-dimension vector  (C Storm, )
          Re: index structure for 114-dimension vector  ("Alexander Staubo", )
           Re: index structure for 114-dimension vector  (Oleg Bartunov, )
            Re: index structure for 114-dimension vector  (Andrew Lazarus, )
             Re: index structure for 114-dimension vector  ("Alexander Staubo", )
       Re: Basic Q on superfluous primary keys  ("Craig A. James", )
    Re: Basic Q on superfluous primary keys  (Ron Mayer, )

Andrew Lazarus <> 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


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