How to process a large XML string passed to a LONG variable?

Question

I am attempting to extract and loop through some XML that is stored in a variable (v_xml_string) that is defined as LONG data type. However, I am receiving an ORA-01460: unimplemented or unreasonable conversion requested when the string value exceeds 20 records in the XML layout below. When I performed a LENGHTB on a sample XML string containing 19 records (just below the threshold of erroring), I get 3895, which I'm assuming is in BYTES...this is not near the 32,760 byte limit of PL/SQL variables defined as LONG. I suppose my other alternative is that I use CLOB datatype instead of LONG.
XML layout:
<?xml version="1.0"?>
<DocumentElement>
  <tblElections>
    <EmpID>872G4</EmpID>
    <MgrNTID>JohnDoe</MgrNTID>
    <Entity>050595</Entity>
    <AddlAmt>1000</AddlAmt>
    <CheckedForSave>Y</CheckedForSave>   
  </tblElections>
</DocumentElement>sample of code where error appers to be occurring:
DECLARE
  v_xml_string LONG;
BEGIN
    FOR v_xml_rec IN (SELECT t.COLUMN_VALUE.extract('/tblElections/EmpID/text()') .getStringVal() EmpID,
                             t.COLUMN_VALUE.extract('/tblElections/MgrNTID/text()') .getStringVal() MgrNTID,
                             t.COLUMN_VALUE.extract('/tblElections/FAEntity/text()') .getStringVal() FAEntity,
                             t.COLUMN_VALUE.extract('/tblElections/AddlSLEAAmt/text()') .getStringVal() AddlSLEAAmt,
                             t.COLUMN_VALUE.extract('/tblElections/CheckedForSave/text()') .getStringVal() CheckedForSave
                        FROM TABLE(xmlsequence(XMLTYPE(v_xml_string) .extract('/DocumentElement/tblElections'))) t)
    LOOP
... <do some stuff here>
   END LOOP;
END;

Answer 1

Strings in SQL are limited to 4000 in length, the long variable will work up to 32K as long as it is not used in SQL, if it goes over 4000 you will get the error.
SQL> declare
  2    l long;
  3  begin
  4    l := rpad('x',32000,'x');
  5    dbms_output.put_line('length is : ' || to_char(length(l)));
  6  end;
  7  /
length is : 32000
PL/SQL procedure successfully completed.
SQL> edi
Wrote file afiedt.sql
  1  declare
  2    l long;
  3    n number;
  4  begin
  5    l := rpad('x',32000,'x');
  6    select length(l) into n from dual;
  7    dbms_output.put_line('length is : ' || to_char(n));
  8* end;
SQL> /
declare
ERROR at line 1:
ORA-01460: unimplemented or unreasonable conversion requested
ORA-06512: at line 6
SQL> edi
Wrote file afiedt.sql
  1  declare
  2    l long;
  3    n number;
  4  begin
  5    l := rpad('x',4000,'x');
  6    select length(l) into n from dual;
  7    dbms_output.put_line('length is : ' || to_char(n));
  8* end;
SQL> /
length is : 4000
PL/SQL procedure successfully completed.
SQL> edi
Wrote file afiedt.sql
  1  declare
  2    l long;
  3    n number;
  4  begin
  5    l := rpad('x',4001,'x');
  6    select length(l) into n from dual;
  7    dbms_output.put_line('length is : ' || to_char(n));
  8* end;
SQL> /
declare
ERROR at line 1:
ORA-01460: unimplemented or unreasonable conversion requested
ORA-06512: at line 6
SQL>