Re: XML schemas and PG column names

Tom Lane wrote:
> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
>
>> I propose that we annotate the schema section RowType elements with the
>> original names, so we would have something like this in the schema section:
>>
>
> 1. Is that legal per the SQL/XML spec?
>

It is certainly legal per XML and XSD specs, and the SQL/XML spec has
annotations using appinfo elements. It would be rather surprising if the
SQL/XML spec forbade annotations such as I propose. The spec is
mind-bogglingly impenetrable, though. Perhaps Peter or Nicholas might know.

> 2. What happens when the column name contains characters that would have
> to be escaped, such as "<" --- haven't you just replaced one de-escaping
> problem with another?
>
>
>

No. say the name is "foo & bar < baz". Then the annotation would be:

<pg:column-name>foo &amp; bar &lt; baz</pg:column-name>

But the difference is that the XML processor will automatically unescape
this value (and re-escape it on output if necessary). The user won't
have to do anything (or shouldn't if their XML processor is worth
anything at all). So in a stylesheet, I'd be able to do something like:

<xsl:for-each select="//[complexType[(at)name="RowType"]//pg:column-name">
<th><xsl:value-of select="." /></th>
</xsl:for-each>

and it would just Do The Right Thing. (If we didn't want the output
re-escaped, say when the otuput format was not XML or HTML, we could
make it do that too).

cheers

andrew