UTL_FILE.WRITE_ERROR when calling utl_file.put in a loop

Question

I have below code in my PL/SQL procedure, which I called in API_XXX.put(it calls utl_file.put) in a while loop. And the l_xmldoc is CLOB from a function of getR

Answer 1

Just a guess, but instead of "to_char(10)" you might try chr(10) to determine/write a newline. Not sure if this will solve your problem, but sometimes very long lines (without newlines) can cause issues.

For example:

declare
    l_clob clob;
    l_char char;
begin
    l_clob := 'Line 1' || chr(10) || 'Line 2' || chr(10);

    for i in 1 .. DBMS_LOB.GETLENGTH(l_clob)
    loop
        l_char := dbms_lob.substr(l_clob, 1, i);

        if (l_char = chr(10)) then
        --if (l_char = to_char(10)) then
            dbms_output.put_line('Found a newline at position ' || i);
        end if;
    end loop;

end;

Notice the difference between chr(10) and to_char(10). Easy enough to test if this solves your problem anyway.

Answer 2

1. Post the Oracle Version you are using! Or we can just guess around...

2. Your fflush will not work as you expect - From the documentation:

   FFLUSH physically writes pending data to the file identified by the file handle. Normally, data being written to a file is buffered. The FFLUSH procedure forces the buffered data to be written to the file. The data must be terminated with a newline character.

3. tbone is abolutely right the line TO_CHAR(10) is wrong! Just try SELECT TO_CHAR(10) FROM DUAL; you will get 10 which you then compare to a single character. A single character will never be '10' since 10 has two characters!

4. Your problem is most likely a buffer-overflow with too large XML-Files, but keep in mind, also other problems on the target system can lead to write_errors, which should be handled.

Solutions

• Quick&Dirty: Since you don't seem to care about performance anyways you can just close the file every X byte and reopen it with A for append. So just add to the loop:

  IF MOD( l_offset, 32000 ) = 0
  THEN
    UTL_FILE.FCLOSE( f_out );
    UTL_FILE.FOPEN( out_fpath, out_fname, f_out, 'a', 32767 );
  END IF;
  

• Use the right tool for the right job: UTL_FILE is not suited for handling complex data. The only usecase for UTL_FILE are small newline-separated lines of text. For everything else you should write RAW bytes! (Which will also allow you porper control over ENCODING, which is currently just mini-vanilly-lucky-guess)

• Write a Java-Stored-Procedure with NIO-Filechannels - fast, safe, nice... But be careful, your program might run 10 times as fast!