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Re: AW: Re: [BUGS] Turkish locale bug

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>
Cc: Sezai YILMAZ <sezaiy(at)ata(dot)cs(dot)hun(dot)edu(dot)tr>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: AW: Re: [BUGS] Turkish locale bug
Date: 2001-02-20 17:23:43
Message-ID: 13047.982689823@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Zeugswetter Andreas SB  <ZeugswetterA(at)wien(dot)spardat(dot)at> writes:
>> Now I'm confused.  Are you saying that we *should* treat identifier case
>> under ASCII rules only?  That seems like a step backwards to me, but
>> then I don't use any non-US locale myself...

> I think we need to treat anything that is not quoted as US_ASCII,
> iirc this is how Informix behaves. Users wanting locale aware identifiers
> would need to double quote those, thus avoiding non ASCII case conversions
> alltogether.

I dug into the SQL99 spec, and I find it appears to have different rules
for identifier folding than for keyword recognition.  Section 5.2 syntax
rules 1-12 make it perfectly clear that they have an expansive idea of
what characters are allowed in identifiers (most of Unicode, it looks
like ;-)).  They also define the case-normalized form of an identifier
in terms of Unicode case translations (rule 21).  But they then say

        28) For the purposes of identifying <key word>s, any <simple Latin
            lower case letter> contained in a candidate <key word> shall
            be effectively treated as the corresponding <simple Latin upper
            case letter>.

It appears to me that to implement the SQL99 rules correctly in a non-C
locale, we need to do casefolding twice.  First, casefold only 'A'..'Z'
and test to see if we have a keyword.  If not, do the casefolding again
using isupper/tolower to produce the normalized form of the identifier.

This would solve Sezai's problem without adding a special case for
Turkish, and it doesn't seem unreasonably slow.  Anyone object to it?

			regards, tom lane

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