Message-ID: <539FB827.3070905@2ndquadrant.com>
Date: Tue, 17 Jun 2014 12:38:15 +0900
From: Ian Barwick <ian@2ndquadrant.com>
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To: Peter Geoghegan <pg@heroku.com>
CC: Tom Lane <tgl@sss.pgh.pa.us>, Michael Paquier <michael.paquier@gmail.com>,
 Josh Berkus <josh@agliodbs.com>, Andres Freund <andres@2ndquadrant.com>,
 Greg Stark <stark@mit.edu>, Jim Nasby <jim@nasby.net>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>,
 Robert Haas <robertmhaas@gmail.com>,
 Albe Laurenz <laurenz.albe@wien.gv.at>
Subject: Re: Doing better at HINTing an appropriate column within
 errorMissingColumn()
References: 
 <CAM3SWZS9-Xr2Ud_j9yrKDctT6xxy16h1EugtSWmLU6Or4CtGAA@mail.gmail.com>
	<A737B7A37273E048B164557ADEF4A58B17CE8DEA@ntex2010i.host.magwien.gv.at>
	<CA+TgmoY+DMJgE+B4M9qP2Uauwu-iJxs0ynCqSEtQZ_Y0TbMYxw@mail.gmail.com>
	<CAM3SWZTpTrpjTEyJT2mMK1MhaA10ZufffpN+HtkfSe0Kkg+maQ@mail.gmail.com>
	<533B31C9.1080403@nasby.net>
	<CAM-w4HOTRoPJHT3J=nEvzQwWUTh5QzW77MGB1umQRL28b2D64g@mail.gmail.com>
	<20140402201602.GV3750@awork2.anarazel.de>
	<WM!fa5058a0cf78e105e4943455e049a6e231537de5b73a550f4e6fbb7aa0182ba1833f03f49d84ffc0ab7bb7c5a90e7f19!@asav-1.01.com>
	<539F7816.1070809@agliodbs.com>
	<CAM3SWZQj1QOFNugKcev4z9ff9CxBfy1qxyxnHitdk+YA-ca2EA@mail.gmail.com>
	<539F8C26.3040500@2ndquadrant.com>
	<CAB7nPqS-YtRHKi0gHCkB2L=G9aiVsZg478kRxO_J280dzm66Xw@mail.gmail.com>
	<27925.1402966428@sss.pgh.pa.us>	<539FA371.4070902@2ndquadrant.com>
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On 14/06/17 11:57, Peter Geoghegan wrote:
> On Mon, Jun 16, 2014 at 7:09 PM, Ian Barwick <ian@2ndquadrant.com> wrote:
>> Howver in this particular use case, as long as it doesn't produce false
>> positives (I haven't looked at the patch) I don't think it would cause
>> any problems (of the kind which would require actively excluding certain
>> languages/character sets), it just wouldn't be quite as useful.
> 
> I'm not sure what you mean by false positives. The patch just shows a
> HINT, where before there was none. It's possible for any number of
> reasons that it isn't the most useful possible suggestion, since
> Levenshtein distance is used as opposed to any other scheme that might
> be better sometimes. I think that the hint given is a generally useful
> piece of information in the event of an ERRCODE_UNDEFINED_COLUMN
> error. Obviously I think the patch is worthwhile, but fundamentally
> the HINT given is just a guess, as with the existing HINTs.

I mean, does it come up with a suggestion in every case, even if there is
no remotely similar column? E.g. would

  SELECT foo FROM some_table

bring up column "bar" as a suggestion if "bar" is the only column in
the table?

Anyway, is there an up-to-date version of the patch available? The one from
March doesn't seem to apply cleanly to HEAD.


Thanks

Ian Barwick


-- 
 Ian Barwick                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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