Re: knngist - 0.8

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dimitri Fontaine <dimitri@2ndQuadrant.fr>
Cc: Greg Stark <gsstark@mit.edu>, Oleg Bartunov <oleg@sai.msu.su>, Robert Haas <robertmhaas@gmail.com>, Teodor Sigaev <teodor@sigaev.ru>, Pgsql Hackers <pgsql-hackers@postgresql.org>
Date: 2010-12-04T21:58:18Z
Lists: pgsql-hackers
Dimitri Fontaine <dimitri@2ndQuadrant.fr> writes:
> Greg Stark <gsstark@mit.edu> writes:
>> I kind of assumed the natural client for KNN-gist was the tsearch full
>> text search indexes handling sorting by relevance. For example if I
>> search for "Postgres DBA" I should find documents where those words
>> appear adjacent first and documents where the two words appear far
>> apart in the document sorted further down. Is that not on the list of
>> operators supported or planned to be supported?

> From the presentation I've seen, the typical use case is more searching
> "PostgreSQL DBA" at 100 km around a known location. Or more typical yet,
> Pizza restaurants around a known place:)

Right offhand I don't see how KNNGIST could usefully be applied to the
problem Greg is thinking about.  A KNNGIST search is only going to be
fast if the target items can be found in a reasonably small part of the
index.  Nearest-neighbor in a geometrically organized index qualifies,
but I don't see how Greg's problem matches the structure of a tsearch
index.

			regards, tom lane