Message-ID: <3FFF129E.6020109@dunslane.net>
Date: Fri, 09 Jan 2004 15:44:14 -0500
From: Andrew Dunstan <andrew@dunslane.net>
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To: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Encoding problems in PostgreSQL with XML data
References: <303E00EBDD07B943924382E153890E5434AA48@cuthbert.rcsinc.local>
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Perhaps the document should be stored in canonical form. See 
http://www.w3.org/TR/xml-c14n

I think I agree with Rod's opinion elsewhere in this thread. I guess the 
"philosophical" question is this: If 2 XML documents with different 
encodings have the same canonical form, or perhaps produce the same DOM, 
are they equivalent? Merlin appears to want to say "no", and I think I 
want to say "yes".

cheers

andrew

Merlin Moncure wrote:

>Peter Eisentraut wrote:
>  
>
>>The central problem I have is this:  How do we deal with the fact that
>>an XML datum carries its own encoding information?
>>    
>>
>
>Maybe I am misunderstanding your question, but IMO postgres should be
>treating xml documents as if they were binary data, unless the server
>takes on the role of a parser, in which case it should handle
>unspecified/unknown encodings just like a normal xml parser would (and
>this does *not* include changing the encoding!).
>
>According to me, an XML parser should not change one bit of a document,
>because that is not a 'parse', but a 'transformation'.
> 
>  
>
>>Rewriting the <?xml?> declaration seems like a workable solution, but
>>    
>>
>it
>  
>
>>would break the transparency of the client/server encoding conversion.
>>Also, some people might dislike that their documents are being changed
>>as they are stored.
>>    
>>
>
>Right, your example begs the question: why does the server care what the
>encoding of the documents is (perhaps indexing)?  ZML validation is a
>standardized operation which the server (or psql, I suppose) can
>subcontract out to another application.
>
>Just a side thought: what if the xml encoding type was built into the
>domain type itself?
>create domain xml_utf8 ...
>Which allows casting, etc. which is more natural than an implicit
>transformation.
>
>Regards,
>Merlin
>
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>  
>