Convert clob to blob

Question

Anyone know an easy way to convert clob data to blob data?
We upgraded a client to 8.1.7.2 and now we can no longer store MS-Word templates to the RDBMS.
I deduce this is because MS-Word templates are binary files.
Earlier versions of 8.1.7 and 8.1.6 allowed us to do this. However, this is no longer the case.
Some of my clob rows are over 6 meg.
I have written some PL/SQL code to basically retrieve the clob data in cursor, loops through the clob in 32767 blocks,
performing dbms_lob.substr, converts that data to hex(major pain), & then write the blocks using dbmbs_lob.write.
I keep getting the proverbial "ORA-06502: PL/SQL: numeric or value error: invalid LOB locator specified: ORA-22275".
Does anyone see flaws in my approach and might have an easier solution?
Thanks!

Answer 1

Here's my code:
REATE OR REPLACE
PROCEDURE p_load_clob_to_blob IS
* Name:           p_load_clob_to_blob
* Parameters: None
* Purpose: This procedure loads the narr_blob column in the narr table_text with clob data from the
* narr column.
* Notes: This procedure assumes that narr table has been altered with narr_blob column added.
* See the SQL below:
*               alter table narr_text add (narr_blob blob);
* Once this procedure executes, the table must altered to drop the narr_text clob column,
* recreate the narr_text as blob, & then repopulate narr_text. See the SQL below:
*                     alter table narr_text drop column narr;
*                    alter table narr_text add (narr blob);
*                    update narr_text set narr = narr_blob;
*                    commit;
* Called By: Sys Admin
* CHANGE LOG
* Changed By Date Change Description
* EAO          01/16/02 Created.
rec_read      INTEGER;
rec_update      INTEGER;
write_cnt INTEGER;
write_amount BINARY_INTEGER;
write_offset INTEGER;
write_loop INTEGER;
total_length      NUMBER;
total_written      NUMBER;
buffer VARCHAR2(32767);
bbuffer RAW(32767);
temp_narr_id NUMBER;
max_loop               INTEGER;
cx                    CLOB;
bx                    BLOB;
bx2                    BLOB;
cur_evt               varchar2(50); -- current event
v_err_descr          varchar2(256);
i INTEGER;
hex                    varchar(32767);
CURSOR c_load_narr_clob IS
     SELECT narr, narr_id
     FROM narr_text
     where narr_id = 6366;
BEGIN
insert_event_log('', 'p_load_clob_to_blob', '', '', '', 'p_load_clob_to_blob started', '');
rec_read := 0;
rec_update := 0;
---Fill file
insert_event_log('', 'p_load_clob_to_blob ','c_load_narr_clob ', '', 'S', 'c_narr_clob started', '');
FOR csr IN c_load_narr_clob LOOP      
     cur_evt := 'Select narr from narr table: ';
     rec_read := rec_read + 1;
     write_loop := 1;
     write_cnt := 0;
     write_offset := 1;           
     total_written := 0;     
     cx := csr.narr;
bx := empty_blob();          
     total_length := DBMS_LOB.GETLENGTH(cx);
     max_loop := (total_length / 32767) + 1;
     if (total_length <= 32767) THEN
          write_amount := total_length;
     ELSE
          write_amount := 32767;
     END IF;
dbms_output.put_line('Length=' || to_char(total_length) || ' Max loop=' || to_char(max_loop) || ' Write Amount=' || to_char(write_amount));
     temp_narr_id := csr.narr_id;
     while write_cnt < max_loop
     loop
--FOR write_loop in 1..max_loop LOOP
          delete temp_blob;
          delete temp_raw;
          commit;
          cur_evt := 'Dbms_lob.substr: ';
          dbms_output.put_line(cur_evt);
buffer := DBMS_LOB.SUBSTR(cx, write_amount, write_offset);
          dbms_output.put_line('Write Amount='|| to_char(write_amount) || ' Write Offset=' || to_char(write_offset) );
cur_evt := 'Hex to Raw Assigment: ';
          dbms_output.put_line(cur_evt);
          bbuffer := null;
          for i in 1..write_amount loop
               hex := numtohex(ascii(substrb(buffer,i,1)));
               bbuffer := bbuffer || hextoraw(hex);
          end loop;
cur_evt := 'Insert temp_raw: ';
          dbms_output.put_line(cur_evt);
          insert into temp_raw(rx)
               values (bbuffer);
          commit;
cur_evt := 'Insert temp_blob: ';
          dbms_output.put_line(cur_evt);
          execute immediate 'insert into temp_blob(bx)
               select TO_LOB(rx) from temp_raw';
          commit;
          cur_evt := 'Select bx2: ';
          dbms_output.put_line(cur_evt);
          bx2 := empty_blob();
          select bx into bx2 from temp_blob;
          cur_evt := 'Dbms_lob.append: ';
          dbms_output.put_line(cur_evt);
          dbms_lob.append(bx, bx2);
     dbms_output.put_line('Write Amount='|| to_char(write_amount) || ' Write Offset=' || to_char(write_offset) );
          write_offset := write_offset + write_amount;
          total_written := total_written + write_amount;
          write_cnt := write_cnt + 1;
          if (write_cnt = max_loop) then
          write_amount := total_length - total_written;
          end if;
END LOOP;
dbms_output.put_line('Total_written = ' || to_char(total_written) );
     cur_evt := 'Upd narr_blob in narr table: ';
     update narr_text
     set narr_blob = bx
     where narr_id = temp_narr_id;
     rec_update := rec_update + 1;
     commit;
END LOOP;
insert_event_log('', 'p_load_clob_to_blob ','c_load_narr_clob ', '', 'C', 'c_narr_clob completed', '');
dbms_output.put_line('Records read=' || to_char(rec_read) || ' Records updated=' || to_char(rec_update) );
insert_event_log('', 'p_load_clob_to_blob', '', '', '', 'p_load_clob_to_blob ended', '');
EXCEPTION
     WHEN OTHERS THEN
     Rollback;
     v_err_descr := 'FATAL ERROR OCCURRED -'||cur_evt||sqlerrm;
     dbms_output.put_line (v_err_descr);
END;
FUNCTION numtohex(v_hex number) return varchar2
is
hex varchar2(4);
num1 number;
num2 number;
begin
num1 := trunc(v_hex/16);
num2 := v_hex-(num1*16);
if ( num1 >= 0 and num1 <= 9 ) then
hex := hex||to_char(num1);
end if;
if num1 = 10 then hex := hex||'A'; end if;
if num1 = 11 then hex := hex||'B'; end if;
if num1 = 12 then hex := hex||'C'; end if;
if num1 = 13 then hex := hex||'D'; end if;
if num1 = 14 then hex := hex||'E'; end if;
if num1 = 15 then hex := hex||'F'; end if;
if ( num2 >= 0 and num2 <= 9 ) then
hex := hex||to_char(num2);
end if;
if num2 = 10 then hex := hex||'A'; end if;
if num2 = 11 then hex := hex||'B'; end if;
if num2 = 12 then hex := hex||'C'; end if;
if num2 = 13 then hex := hex||'D'; end if;
if num2 = 14 then hex := hex||'E'; end if;
if num2 = 15 then hex := hex||'F'; end if;
return hex;
end;