How do I fix "numeric or value error" message? - oracle

Question

I have been stuck with this issue now all morning. I actually saw this code here and decide to use it for our purpose here.
The issue that I am running into is that when we execute the code, sometimes it writes a file from db to the folder.
Other times, we get "numeric or value error"
Can any expert please help me fix it?
Here is the code I am using:
create or replace
PROCEDURE getfile(pfname VARCHAR2, display_name IN VARCHAR2)
IS
vblob BLOB;
vstart NUMBER := 1;
bytelen NUMBER := 32000;
len NUMBER;
my_vr RAW(32000);
x NUMBER;
v_name VARCHAR2(32760);
lv_str_len NUMBER;
l_output utl_file.file_type;
BEGIN
-- define output directory
--lv_str_len := Length(pfname);
--v_name := display_name||upper(substr(pfname,lv_str_len-3,lv_str_len));
v_name := display_name;
l_output := utl_file.Fopen('My_DIR', v_name, 'w', 32760);
-- get length of blob
SELECT dbms_lob.Getlength(FILENAME)
INTO len
FROM GENERAL.GUBFILE
WHERE gubfile_name = pfname;
-- dbms_output.put_line('Length: '||len);
-- save blob length
x := len;
-- select blob into variable
SELECT BLOBVALUE
INTO vblob
FROM FILES
WHERE filename = pfname;
-- if small enough for a single write
IF len < 32760 THEN
-- dbms_output.put_line('Single write ');
utl_file.Put_raw(l_output, vblob);
utl_file.Fflush(l_output);
ELSE -- write in pieces
-- dbms_output.put_line('multi write '||vstart);
vstart := 1;
WHILE vstart < len LOOP
dbms_lob.READ(vblob, bytelen, vstart, my_vr);
utl_file.Put_raw(l_output, my_vr);
utl_file.Fflush(l_output);
-- set the start position for the next cut
vstart := vstart + bytelen;
-- set the end position if less than 32000 bytes
x := x - bytelen;
IF x < 32000 THEN
bytelen := x;
END IF;
END LOOP;
END IF;
dbms_output.Put_line('End');
utl_file.Fclose(l_output);
END getfile;
The exact error is:
ORA-06502: PL/SQL: numeric or value error
ORA-06512: at "USER.GETFILE", line 40
ORA-06512: at line 8

Answer 1

The error comes from utl_file.put_raw.
The maximum size of the buffer parameter is 32767 bytes.
You check for IF len < 32760 THEN, however, I see no guarantee in your code, that the len variable actually holds the length of the vblob variable that is the buffer in the put_raw call.
So I suppose the vblob variable's actual length is longer then 32767 and that is the reason for the error.
Hence I suggest to delete this piece of code:
IF len < 32760 THEN
-- dbms_output.put_line('Single write ');
utl_file.Put_raw(l_output, vblob);
utl_file.Fflush(l_output);
ELSE
also the END IF; of course, and always go for the 'write in pieces' branch.
I see now, you've done this based on the Burleson example which is good http://www.dba-oracle.com/t_writing_blob_clob_os_file.htm
but you see, unlike you, Burleson gets the len variable and the vblob variable from the same table and the same field.
-- get length of blob
SELECT dbms_lob.getlength(productblob)
INTO len
FROM products
WHERE id = product_id;
-- save blob length
x := len;
-- select blob into variable
SELECT product_blob
INTO vblob
FROM products
WHERE id = product_id;
EDIT
So an other option would be to fix the select for getting length. This means you'll have to replace this select:
-- get length of blob
SELECT dbms_lob.Getlength(FILENAME)
INTO len
FROM GENERAL.GUBFILE
WHERE gubfile_name = pfname;
with this:
-- get length of blob
SELECT dbms_lob.Getlength(BLOBVALUE)
INTO len
FROM FILES
WHERE filename = pfname;