ORA-31181: PL/SQL DOM handle accesses node that is no longer available

Question

I'm trying to extract data from Oracle SQL tables which is working to a point when I put the write to file outside the loop like the example below. But in the code below this code when I put the write to file inside loop it falls over with ORA-31181 error.

What I'm trying to do on a bigger scale is get a load of XML to a file by writing to a clob outputting it to a flat file every time it goes around the loop.

DECLARE -- this version of code works as the write to is outside loop

 l_file    UTL_FILE.FILE_TYPE;
 l_clob    CLOB;
 l_buffer  VARCHAR2(32767);
 l_amount  BINARY_INTEGER := 32767;
 l_pos     INTEGER := 1;
 l_extract_dir               CONSTANT dba_directories.directory_name%TYPE:= 'REPORTS_OUT_DIR';   -- \\data2\data\download\d7prdv1\prsrepreports  


 l_xmltype XMLTYPE;
 l_domdoc dbms_xmldom.DOMDocument;
 l_root_node dbms_xmldom.DOMNode;     

 l_message_node            dbms_xmldom.DOMNode;

 l_production_element    dbms_xmldom.DOMElement;
 l_production_node       dbms_xmldom.DOMNode;

  -- production XML elements, node, text
 l_prod_element                   dbms_xmldom.DOMElement;     
 l_prod_node         dbms_xmldom.DOMNode;
 l_prod_t_node          dbms_xmldom.DOMNode;
 l_prod_text          dbms_xmldom.DOMText;
-- production XML elements, node, text, node


 CURSOR c_production
 IS SELECT prod.cre_surr_id            as cre_surr_id
         , prod.production_type        as prodCategoryType
    from productions prod            
    where prod.cre_surr_id in (1753959927,1753959929);
 BEGIN 
   UTL_FILE.FCLOSE_ALL;
   l_file := UTL_FILE.fopen(l_extract_dir , 'Sample2.dat', 'w', 32767);

 -- Create an empty XML document
 l_domdoc := dbms_xmldom.newDomDocument;

 -- Create a root node
 l_root_node := dbms_xmldom.makeNode(l_domdoc);

 -- Create a message root node
 l_message_node := dbms_xmldom.appendChild( l_root_node
                                      ,   dbms_xmldom.makeNode(dbms_xmldom.createElement(l_domdoc, 'message' ))
                                     );     

   FOR production_rec in c_production LOOP

     l_production_element := dbms_xmldom.createElement(l_domdoc, 'production' );
     l_production_node    := dbms_xmldom.appendChild(l_message_node,dbms_xmldom.makeNode(l_production_element));  

    -- prodCategoryType
     l_prod_element := dbms_xmldom.createElement(l_domdoc, 'prodCategoryType' );
     l_prod_node   := dbms_xmldom.appendChild(l_production_node,dbms_xmldom.makeNode(l_prod_element));
     l_prod_text    := dbms_xmldom.createTextNode(l_domdoc, production_rec.prodCategoryType );
     l_prod_t_node   := dbms_xmldom.appendChild(l_prod_node,dbms_xmldom.makeNode(l_prod_text));

  END LOOP;

  l_xmltype := dbms_xmldom.getXmlType(l_domdoc);
  dbms_xmldom.freeDocument(l_domdoc);
  l_clob := l_xmltype.getClobVal;   
  DBMS_LOB.read (l_clob, l_amount, l_pos, l_buffer);
  UTL_FILE.put(l_file, l_buffer);
  l_pos := l_pos + l_amount;
  UTL_FILE.fclose(l_file);

END;

The code below creates an error message when I put the write to file inside the loop.

The error message is below.

Error at line 1 ORA-31181: PL/SQL DOM handle accesses node that is no longer available ORA-06512: at "XDB.DBMS_XMLDOM", line 4735 ORA-06512: at "XDB.DBMS_XMLDOM", line 4762 ORA-06512: at line 52

DECLARE -- this version of code DOES not work and creates the ORA-31181 error

 l_file    UTL_FILE.FILE_TYPE;
 l_clob    CLOB;
 l_buffer  VARCHAR2(32767);
 l_amount  BINARY_INTEGER := 32767;
 l_pos     INTEGER := 1;
 l_extract_dir               CONSTANT dba_directories.directory_name%TYPE:= 'REPORTS_OUT_DIR';   -- \\data2\data\download\d7prdv1\prsrepreports  


 l_xmltype XMLTYPE;
 l_domdoc dbms_xmldom.DOMDocument;
 l_root_node dbms_xmldom.DOMNode;     

 l_message_node            dbms_xmldom.DOMNode;

 l_production_element    dbms_xmldom.DOMElement;
 l_production_node       dbms_xmldom.DOMNode;

  -- production XML elements, node, text
 l_prod_element                   dbms_xmldom.DOMElement;     
 l_prod_node         dbms_xmldom.DOMNode;
 l_prod_t_node          dbms_xmldom.DOMNode;
 l_prod_text          dbms_xmldom.DOMText;
 -- production XML elements, node, text, node


 CURSOR c_production
 IS SELECT prod.cre_surr_id            as cre_surr_id
         , prod.production_type        as prodCategoryType
    from productions prod            
    where prod.cre_surr_id in (1753959927,1753959929);
 BEGIN 
   UTL_FILE.FCLOSE_ALL;
   l_file := UTL_FILE.fopen(l_extract_dir , 'Sample2.dat', 'w', 32767);

  -- Create an empty XML document
  l_domdoc := dbms_xmldom.newDomDocument;

  -- Create a root node
  l_root_node := dbms_xmldom.makeNode(l_domdoc);

  -- Create a message root node
  l_message_node := dbms_xmldom.appendChild( l_root_node
                                      , dbms_xmldom.makeNode(dbms_xmldom.createElement(l_domdoc, 'message' ))
                                     );     



   FOR production_rec in c_production LOOP

     l_production_element := dbms_xmldom.createElement(l_domdoc, 'production' );
     l_production_node    := dbms_xmldom.appendChild(l_message_node,dbms_xmldom.makeNode(l_production_element));  

    -- prodCategoryType
     l_prod_element := dbms_xmldom.createElement(l_domdoc, 'prodCategoryType' );
     l_prod_node   := dbms_xmldom.appendChild(l_production_node,dbms_xmldom.makeNode(l_prod_element));
     l_prod_text    := dbms_xmldom.createTextNode(l_domdoc, production_rec.prodCategoryType );
     l_prod_t_node   := dbms_xmldom.appendChild(l_prod_node,dbms_xmldom.makeNode(l_prod_text));



   l_xmltype := dbms_xmldom.getXmlType(l_domdoc);
   dbms_xmldom.freeDocument(l_domdoc);
   l_clob := l_xmltype.getClobVal;   
   DBMS_LOB.read (l_clob, l_amount, l_pos, l_buffer);
   UTL_FILE.put(l_file, l_buffer);
    l_pos := l_pos + l_amount;


    END LOOP;

   UTL_FILE.fclose(l_file);

 END;

Answer 1

Easiest way.

begin     
for rec in ( SELECT xmlserialize(content xmlelement("production",
                xmlelement("prodCategoryType",prod.production_type)) as varchar2(4000)) val from productions prod ) loop
dbms_output.put_line(rec.val) ;   
end loop;                                    
end;    

Or in your code add v_temp DBMS_XMLDOM.DOMNODE; in declaration and replace dbms_xmldom.freeDocument(l_domdoc); with temp:= DBMS_XMLDOM.REMOVECHILD(l_message_node,l_production_node);