Feedback-ID: i131946ab:Fastmail
Message-ID: <0fc339d4-3388-3849-4507-ef0fe0c783fa@enterprisedb.com>
Date: Tue, 13 Sep 2022 08:32:43 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0)
 Gecko/20100101 Thunderbird/102.2.2
Subject: Re: postgres_fdw hint messages
To: Nathan Bossart <nathandbossart@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>, Robert Haas
 <robertmhaas@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
References: <b1f9f399-3a1a-b554-283f-4ae7f34608e2@enterprisedb.com>
 <CA+TgmoY+BuSZm-Fbxx5zC6SuML=2F9YvaYuzVAJ=XyE65BnchQ@mail.gmail.com>
 <1929340.1661531738@sss.pgh.pa.us> <20220901223128.GA932597@nathanxps13>
 <789102.1662073729@sss.pgh.pa.us> <20220901233120.GA934376@nathanxps13>
 <20220902212609.GA1216541@nathanxps13> <YxKn9El8Km/3IZuI@paquier.xyz>
 <1267654.1662170814@sss.pgh.pa.us> <20220903043058.GA1264318@nathanxps13>
Content-Language: en-US
From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
In-Reply-To: <20220903043058.GA1264318@nathanxps13>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/0fc339d4-3388-3849-4507-ef0fe0c783fa%40enterprisedb.com>
Precedence: bulk

On 03.09.22 06:30, Nathan Bossart wrote:
> On Fri, Sep 02, 2022 at 10:06:54PM -0400, Tom Lane wrote:
>> I think the distance limit of 5 is too loose though.  I see that
>> it accommodates examples like "passfile" for "password", which
>> seems great at first glance; but it also allows fundamentally
>> silly suggestions like "user" for "server" or "host" for "foo".
>> We'd need something smarter than Levenshtein if we want to offer
>> "passfile" for "password" without looking stupid on a whole lot
>> of other cases --- those words seem close, but they are close
>> semantically not textually.
> 
> Yeah, it's really only useful for simple misspellings, but IMO even that is
> rather handy.
> 
> I noticed that the parse_relation.c stuff excludes matches where more than
> half the characters are different, so I added that here and lowered the
> distance limit to 4.  This seems to prevent the silly suggestions (e.g.,
> "host" for "foo") while retaining the more believable ones (e.g.,
> "passfile" for "password"), at least for the small set of examples covered
> in the tests.

I think this code is compact enough and the hints it produces are 
reasonable, so I think we could go with it.

I notice that for column misspellings, the hint is phrased "Perhaps you 
meant X." whereas here we have "Did you mean X?".  Let's make that uniform.