Thread: XMLSerialize: version and explicit XML declaration

Hi,

I'm working on the flags VERSION (X076), INCLUDING XMLDECLARATION, and
EXCLUDING XMLDECLARATION (X078) for XMLSerialize, and I have a question
for SQL/XML experts on the list.

Is there any validation mechanism for VERSION <character string
literal>? The SQL/XML spec says

"The <character string literal> immediately contained in <XML serialize
version> shall be '1.0' or '1.1', or it shall identify some successor to
XML 1.0 and XML 1.1."

I was wondering if a validation here would make any sense, since
XMLSerialize is only supposed to print a string --- not to mention that
validating "some successor to XML 1.0 and XML 1.1" can be challenging :)
But again, printing an "invalid" XML string also doesn't seem very nice.

The oracle implementation accepts pretty much anything:

SQL> SELECT xmlserialize(DOCUMENT xmltype('<foo><bar>42</bar></foo>')
VERSION 'foo') AS xml FROM dual;

XML
--------------------------------------------------------------------------------
<?xml version="foo"?>
<foo>
  <bar>42</bar>
</foo>


In db2, anything other than '1.0' raises an error:

db2 => SELECT XMLSERIALIZE(CONTENT XMLELEMENT(NAME "db2",service_level)
AS varchar(100) VERSION '1.0' INCLUDING XMLDECLARATION) FROM
sysibmadm.env_inst_info;

1                                                                                                 
 
----------------------------------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?><db2>DB2
v11.5.9.0</db2>                                      

  1 record(s) selected.


db2 => SELECT XMLSERIALIZE(CONTENT XMLELEMENT(NAME "db2",service_level)
AS varchar(100) VERSION '1.1' INCLUDING XMLDECLARATION) FROM
sysibmadm.env_inst_info;
SQL0171N  The statement was not processed because the data type, length or
value of the argument for the parameter in position "2" of routine
"XMLSERIALIZE" is incorrect. Parameter name: "".  SQLSTATE=42815

Any thoughts on how we should approach this feature?

Thanks!

Best, Jim

Jim Jones <jim.jones@uni-muenster.de> writes:
> Is there any validation mechanism for VERSION <character string
> literal>?

AFAICS, all we do with an embedded XML version string is pass it to
libxml2's xmlNewDoc(), which is the authority on whether it means
anything.  I'd be inclined to do the same here.

            regards, tom lane