Re: New XML section for documentation

Bruce Momjian wrote:
> XML Document Support
> ====================
> XML support is not one capability, but a variety of features
> supported by a database.

database system

> Storage
> -------
> PostgreSQL stores XML documents as ordinary text documents.

It is "possible" to do that, but this sounds like it's done
automatically or implicitly. Maybe:

"PostgreSQL does not have a specialized XML data type. The recommended
way is to store XML documents as text."

> Import/Export
> -------------
> Because XML documents are stored as normal text documents, they can
> be imported/exported with little complexity.

Import/export refers to exporting schema data with XML decorations. Of
course you can export column data trivially, but that's not what this
is about.

> Validation
> ----------
> /contrib/xml2 has a function called xml_valid() that can be used in
> a CHECK constraint to enforce that a field contains valid XML. It
> does not support validation against a specific XML schema.

Then this is not validation but only checking for well-formedness. The
xml2 README says so, in fact.

> Indexing
> --------

I think the expression index capability combined with contrib/xml2 is
more relevant here than the full-text search capability.

> Transforming
> ------------
> /contrib/xml2 supports XSL transformations.

That's XSLT.

> XML to SQL Mapping
> -------------------
> This involves converting XML data to and from relational structures.
> PostgreSQL has no internal support for such mapping, and relies on
> external tools to do such conversions.

Are there instances of such tools?

--
Peter Eisentraut
http://developer.postgresql.org/~petere/