Oracle SQL - Extracting clob value from XML with repeating nodes

Question

Hi All,
I am attempting to run SQL on a table (called test_xml with a column xml_data [data type xmltype]). The column contains xml with repeating nodes (description). The following statement runs successfully when the node contains data of a non clob size:
SELECT
extractvalue (Value (wl), '*/description')
FROM test_xml
, TABLE (xmlsequence (extract (xml_data, '*/record'))) wl
but fails when description node contains a lot of data:
ORA-01706: user function result value was too large
I amended my query:
SELECT
extractvalue(Value (wl), '*/description').getClobVal()
FROM test_xml
, TABLE (xmlsequence (extract (xml_data, '*/record'))) wl
but this fails with:
ORA-22806: not an object or REF
Thanks in Advance

Answer 1

Hi Greg,
11.2.0.2.0 (Although I will need to do this on my work instance also which is 10.2.0.4)That's gonna be a problem...
Direct CLOB projection is supported starting with 11.2.0.2, using XMLTable or XMLCast/XQuery functions (extractvalue, extract, xmlsequence are deprecated now) :
SELECT x.*
FROM test_xml t
   , XMLTable(
       '/*/record'
       passing t.xml_data
       columns
         description  clob path 'description'
     ) x
;On prior versions, implicit conversions will occur to VARCHAR2 datatype, hence the limitation observed.
AFAIK you have two options on 10.2.0.4 :
1) Using Object-Relational storage, with the xdb:SQLType="CLOB" annotation.
2) Using the following trick :
SELECT dbms_xmlgen.convert(x.description.getClobVal(), 1) as description
FROM test_xml t
   , XMLTable(
       '/*/record'
       passing t.xml_data
       columns
         description  xmltype path 'description/text()'
     ) x
;