| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)heroku(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(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>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, 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: | 2014-07-23 20:10:19 |
| Message-ID: | 20140723201019.GC5475@eldon.alvh.no-ip.org |
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| Lists: | pgsql-hackers |
Peter Geoghegan wrote:
> For some reason I thought that that was what Michael was proposing - a
> more comprehensive move of code into core than the structuring that I
> proposed. I actually thought about a Levenshtein distance operator at
> one point months ago, before I entirely gave up on that. The
> MAX_LEVENSHTEIN_STRLEN limitation made me think that the Levenshtein
> distance functions are not suitable for core as is (although that
> doesn't matter for my purposes, since all I need is something that
> accommodates NAMEDATALEN sized strings). MAX_LEVENSHTEIN_STRLEN is a
> considerable limitation for an in-core feature. I didn't get around to
> forming an opinion on how and if that should be fixed.
I had two thoughts:
1. Should we consider making levenshtein available to frontend programs
as well as backend?
2. Would it provide better matching to use Damerau-Levenshtein[1] instead
of raw Levenshtein?
.oO(Would anyone be so bold as to attempt to implement bitap[2] using
bitmapsets ...)
[1] http://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_distance
[2] http://en.wikipedia.org/wiki/Bitap_algorithm
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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