pá 24. 1. 2025 v 14:48 odesílatel Jim Jones <jim.jo...@uni-muenster.de> napsal:
> > On 24.01.25 13:48, Pavel Stehule wrote: > > Lot of users use XML functions without XMLDOCUMENT now. The doc should to > > help with a reply to question where and when I need (I can) use this > > function. This should > > be in context of Postgres where every XML expr returns XML value, so > > sentence > > creates an XML value from XML expression is still very confusing > > > > What some like > > > > "SQL/XML introduces XMLDOCUMENT function to returns a document node > > from XML tree of some XML value. > > This has not any sense (because XML in Postgres is always materialized > > to string) in PostgreSQL implementation of XML, and the function just > > returns > > input value". Or some like that. > > > I see. I tried to incorporate your suggestion in the text: > > In the SQL/XML specification, the XMLDocument (X030) function is > designed to return a document node from a given XML value expression. > Since PostgreSQL handles XML values as materialized strings rather than > tree structures, this function does not produce a document node > structure but instead returns the validated input <type>xml</type> value > as-is. The input <type>xml</type> value can include any valid XML > content, such as elements, text, or a mixture of both. This function > does not require the input to have a single root element and does not > wrap the result in one. Validation of the <type>xml</type> input value > depends on the current <xref linkend="guc-xmloption"/> setting. If the > input <type>xml</type> value is NULL, the function returns NULL. This > function ensures compatibility with the SQL/XML specification, making it > particularly useful when migrating SQL queries from other database > systems that also implement this standard. > > Let me know if it is still confusing ... > it is ok for me now. Thank you Pavel > > Thanks! > > Best, Jim > >
