XMLDOM and CDATA

Question

Guru's,
I have a requirement using PL/SQL whereby I need to store more that 32K bytes of HTML in an XML Element. Since the content is HTML, it seems to me that I have to use the CDATA method of XMLDOM
(for example item_node := xmldom.appendChild(item_node, xmldom.makeNode(xmldom.createCDATASection(doc, p_bodycopy)));)
My issue is that the createCDATASection can only handle a VARCHAR2, and I require it to handle (at most) 64K of information.
I can use the AppendData procedure w/ Character data, but that creates decode,translation and transformation issues.
Is there any light at the end of this tunnel? or should I punt.
The following works very well for everything <= 32K
item_elmt := xmldom.createElement(doc, 'BodyCopy');
item_node := xmldom.appendChild(root_node, xmldom.makeNode(item_elmt));
item_node := xmldom.appendChild(item_node, xmldom.makeNode(xmldom.createCDATASection(doc, p_bodycopy)));
I am looking for a solution for content >32K
Any insight is much appreciated.
-Scot

Answer 1

Hi Scot. Unfortunately most of the xml packages and functions are brain dead when it comes to handling large data. Most are implicitly tied to varchar limits and lob limitations in PL/SQL.
To get a CDATA element exactly as you describe, I think you need to resort to building it up from 1st principles using lob methods.
e.g.
declare
v_lob clob;
v_lob_temp clob;
begin
v_lob := '<FamilyHistory><![CDATA[';
select x.bigdata into v_lob_temp from x1 x where x.item='mysample';
DBMS_LOB.APPEND(v_lob, v_lob_temp );
DBMS_LOB.APPEND(v_lob, ']]></FamilyHistory>');
insert into x2 values('mysample',v_lob);
end;
There is an approach using xmltype views based on object types, but these will implicitly xml encode your clob rather than quote it as CDATA (and I don't know a way to prevent this).
e.g.
CREATE TABLE x1 (item varchar(25) primary key, bigdata clob);
-- (insert a very large record)
CREATE OR REPLACE TYPE x1_t AS OBJECT
(Holder varchar(25),BookData CLOB);
CREATE OR REPLACE VIEW vx1 OF XMLTYPE
WITH OBJECT ID (ExtractValue(sys_nc_rowinfo$, '/ROW/HOLDER')) AS
SELECT sys_XMLGen(x1_t(x.item, x.bigdata)) from x1 x;
Here's a sample entry:
SELECT
     extractvalue(x.SYS_NC_ROWINFO$,'/ROW/HOLDER') as holder
     ,'xml_length: ' || dbms_lob.getlength(x.SYS_NC_ROWINFO$.getclobval()) as xml_length
FROM vx1 x;
HOLDER XML_LENGTH
mysample xml_length: 324198
Note sql*plus has a problem querying this:
SQL> select * from vx1;
ERROR:
OCI-31167: XML nodes over 64K in size cannot be inserted
Unless we just go for the clob. In this example the "BOOKDATA" is pure unencoded XML in table X1, but automatically encoded in the xmltype view vx1:
SQL> set long 200
SQL> select (SYS_NC_ROWINFO$).GETCLOBVAL() from vx1;
(SYS_NC_ROWINFO$).GETCLOBVAL()
&lt;?xml version=&quot;1.0&quot;?&gt;
&lt;ROW&gt;
&lt;HOLDER&gt;mysample&lt;/HOLDER&gt;
&lt;BOOKDATA&gt;&amp;lt;books&amp;gt;
&amp;lt;book id=&amp;quot;1&amp;quot;&amp;gt;
&amp;lt;title&amp;gt;the book 1 title&amp;lt;/title&amp;gt;
&amp;lt;/book&amp;gt;
&amp;lt;book id=&amp;quot;2&amp;qu