| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Abhijit Menon-Sen <ams(at)2ndquadrant(dot)com>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org>, Josh Berkus <josh(at)agliodbs(dot)com>, Ian Barwick <ian(at)2ndquadrant(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Jim Nasby <jim(at)nasby(dot)net>, Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at> |
| Subject: | Re: Doing better at HINTing an appropriate column within errorMissingColumn() |
| Date: | 2014-11-19 17:33:58 |
| Message-ID: | CAM3SWZRy8i98pvVw-YcQxSgT8ZoXBmx_SL3p2VEse1vC4jjQ_w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Nov 19, 2014 at 5:43 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> I think we would be well-advised not to start inventing our own
> approximate matching algorithm. Peter's suggestion boils down to a
> guess that the default cost parameters for Levenshtein suck, and your
> suggestion boils down to a guess that we can fix the problems with
> Peter's suggestion by bolting another heuristic on top of it - and
> possibly running Levenshtein twice with different sets of cost
> parameters. Ugh.
I agree.
While I am perfectly comfortable with the fact that we are guessing
here, my guesses are based on what I observed to work well with real
schemas, and simulated errors that I thought were representative of
human error. Obviously it's possible that another scheme will do
better sometimes, including for example a scheme that picks a match
entirely at random. But on average, I think that what I have here will
do better than anything else proposed so far.
--
Peter Geoghegan
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