From: Tom Lane <tgl@sss.pgh.pa.us>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
cc: tanghy.fnst@fujitsu.com, smithpb2250@gmail.com,
        peter.eisentraut@enterprisedb.com, david.zhang@highgo.ca,
        pgsql-hackers@lists.postgresql.org
Subject: Re: Support tab completion for upper character inputs in psql
In-reply-to: <20210423.123407.440405986257584017.horikyota.ntt@gmail.com>
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Comments: In-reply-to Kyotaro Horiguchi <horikyota.ntt@gmail.com>
	message dated "Fri, 23 Apr 2021 12:34:07 +0900"
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Date: Fri, 23 Apr 2021 00:17:35 -0400
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Kyotaro Horiguchi <horikyota.ntt@gmail.com> writes:
> At Thu, 22 Apr 2021 23:17:19 -0400, Tom Lane <tgl@sss.pgh.pa.us> wrote in 
>> Doesn't seem like a good idea, because that locks us into an assumption
>> that the downcasing conversion doesn't change the string's physical
>> length.  There are a lot of counterexamples to that :-(.  I'm not sure

> Mmm. I didn't know of that.

The two examples I know of offhand are in German (eszett "ß" downcases to
"ss") and Turkish (dotted "Í" downcases to "i", likewise dotless "I"
downcases to "ı"; one of each of those pairs is an ASCII letter, the
other is not).  Depending on which encoding is in use, these
transformations *could* be the same number of bytes, but they could
equally well not be.  There are probably other examples.

			regards, tom lane