Three-byte Unicode characters

[ This email to hackers from last night got lost so I am remailing.]

Tom Lane wrote:
> "John Hansen" <john(at)geeknet(dot)com(dot)au> writes:
> >> That is backpatched to 8.0.X. Does that not fix the problem reported?
>
> > No, as andrew said, what this patch does, is allow values > 0xffff and
> > at the same time validates the input to make sure it's valid utf8.
>
> The impression I get is that most of the 'Unicode characters above
> 0x10000' reports we've seen did not come from people who actually needed
> more-than-16-bit Unicode codepoints, but from people who had screwed up
> their encoding settings and were trying to tell the backend that Latin1
> was Unicode or some such. So I'm a bit worried that extending the
> backend support to full 32-bit Unicode will do more to mask encoding
> mistakes than it will do to create needed functionality.
>
> Not that I'm against adding the functionality. I'm just doubtful that
> the reports we've seen really indicate that we need it, or that adding
> it will cut down on the incidence of complaints :-(

OK, I got on the IRC server and talked to folks who actually understand
this. They say there are Chinese who are reporting this problem, so I
Googled and found this:

http://www.yale.edu/chinesemac/pages/charset_encoding.html#Unicode

See the paragraph with "Supplementary Ideographic Plane". You will see
that paragraph says:

The Supplementary Ideographic Plane (SIP) currently contains 42,711
additional characters in "CJK Unified Ideographs Extension B"
(U+20000-2A6D6). The PDF chart for this is available at:
http://www.unicode.org/charts/PDF/U20000.pdf

I assume it is that U+20000-2A6D6 range that people are complaining
about.

So, we do have a bug, and we are probably going to need to fix it in
8.0.X.

I apologize to people who reported this problem and I wasn't attentive
to the seriousness of it.

--
Bruce Momjian | http://candle.pha.pa.us
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