Re: COPY for CSV documentation - Mailing list pgsql-patches

From Andrew Dunstan
Subject Re: COPY for CSV documentation
Date
Msg-id 2365.24.211.141.25.1081689176.squirrel@www.dunslane.net
Whole thread Raw
In response to Re: COPY for CSV documentation  (Bruce Momjian <pgman@candle.pha.pa.us>)
Responses Re: COPY for CSV documentation  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-patches
Bruce Momjian said:
>> >Yes, my worry is that someone will use a multibyte character that the
>> >system sees as several bytes and enters CSV mode.
>> >
>>
>>
>> How about if we specify it explicitly, like BINARY, instead of it
>> being  implied by the length of DELIMITER?
>>
>> COPY a FROM stdin CSV DELIMITER ',"';
>>
>> That would make the patch somewhat more extensive, but maybe not
>> hugely  more invasive (I tried to keep it as uninvasive as possible).
>> I could do  that, I think.
>
> That's what I was wondering.  Is triggering CSV for multi-character
> delimiters a little too clever?  This reminds me of the use of LIMIT
> X,Y with no indication which is limit and which is offset.
>
> We certainly could code to prevent the multibyte problem I mentioned,
> but should we?


I confess that in my anglocentric world I have remained lamentably
ignorant of how MBCS works. Just reading up a little, and looking over
some of our code (e.g. the scanner) it looks like the simple solution
would be to check that the delimiter was 8-bit clean. (I assume that ASCII
is a subset of every MBCS we support - is that correct?)

However ...

>
> I am thinking just:
>
>> COPY a FROM stdin WITH CSV ',"';
>
> or
>
>> COPY a FROM stdin WITH DELIMITER "," QUOTE '"' EQUOTE '"';
>
> EQUOTE for embedded quote.  These are used in very limited situations
> and don't have to be reserved words or anything.
>
> I can help with these changes if folks like them.
>


I prefer either the first, because it ensures things are specified
together.

If you want to do that I will work on some regression tests.

cheers

andrew





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