Re: Support UTF-8 files with BOM in COPY FROM

On Mon, Sep 26, 2011 at 2:38 PM, Peter Eisentraut <peter_e(at)gmx(dot)net> wrote:
> On mån, 2011-09-26 at 13:19 -0400, Robert Haas wrote:
>> The thing that makes me doubt that is this comment from Tatsuo Ishii:
>>
>> TI> COPY explicitly specifies the encoding (to be UTF-8 in this case).
>> So
>> TI> I think we should not regard U+FEFF as "BOM" in COPY, rather we
>> should
>> TI> regard U+FEFF as "ZERO WIDTH NO-BREAK SPACE".
>>
>> If a BOM is confusable with valid data, then I think recognizing it
>> and discarding it unconditionally is no good - you could end up where
>> COPY OUT, TRUNCATE, COPY IN changes the table contents.
>
> We did recently accept a patch for psql -f to skip over a UTF-8
> byte-order mark.  We had a lot of this same discussion there.

But that case is different, because zero-width, non-breaking space has
no particular meaning in an SQL script - it's either going to be
ignored as a BOM, ignored as whitespace, or an error. But inside a
file being subjected to COPY it might be confusable with data that the
user wanted to end up in some table.

--
Robert Haas
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