Loop cursor of ALL_MVIEWS generate PL/SQL Error ORA-06502 - plsql

Question

i wrote a procedure that deals with writing the contents of the QUERY column of ALL_MVIEWS to a file:
DECLARE
v_out_dir_name VARCHAR2(30) := 'DIR_TEST';
v_out_dir_path VARCHAR2(60);
v_count_object_elab NUMBER := 0;
CURSOR c_mviews IS
SELECT
LOWER(MVIEW_NAME) || '.sql' AS FILE_NAME
, QUERY AS SCRIPT
FROM ALL_MVIEWS
;
v_file UTL_FILE.file_type;
BEGIN
FOR r_mview IN c_mviews LOOP
v_file := UTL_FILE.fopen (v_out_dir_name, r_mview.FILE_NAME, 'w');
UTL_FILE.putf (v_file, r_mview.SCRIPT);
UTL_FILE.fclose (v_file);
v_count_object_elab := v_count_object_elab + 1;
END LOOP;
IF v_count_object_elab = 0
THEN
DBMS_OUTPUT.PUT_LINE('NESSUN FILE ELABORATO');
END IF;
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('ERRORE = ' || SQLERRM);
IF UTL_FILE.IS_OPEN (v_file) THEN
UTL_FILE.FCLOSE (v_file);
END IF;
RAISE;
END;
/
But the "FOR r_mview IN c_mviews LOOP" statement generates the following error:
Report error -
ORA-06502: PL/SQL: errore di numero o valore
ORA-06512: a line 35
ORA-06512: a line 16
ORA-06512: a line 16
06502. 00000 - "PL/SQL: numeric or value error%s"
*Cause: An arithmetic, numeric, string, conversion, or constraint error
occurred. For example, this error occurs if an attempt is made to
assign the value NULL to a variable declared NOT NULL, or if an
attempt is made to assign an integer larger than 99 to a variable
declared NUMBER(2).
*Action: Change the data, how it is manipulated, or how it is declared so
that values do not violate constraints.
The error is thrown on a materialized view that has QUERY_LEN = 39000.
How can I solve the problem?
Many thanks in advance.

Answer 1

I don't think you are using UTL_FILE correctly. The putf() procedure is for writing and formatting (using printf() style). Try using just put() instead. I did run your script on my database and it executed fine with putf() and put(), but put() is more appropriate.
Also, beware that QUERY is a LONG. If you have a query over 32k I think you will get the error you are seeing. There are some great write-ups online about how awful LONGs are to work with.
I think easiest thing to do is convert the LONG to CLOB with a CREATE TABLE, read that table and then drop it. Here is a routine to do just that. It will create a copy of all_mviews and convert the query to a CLOB and write that in chunks to a file per view.
DECLARE
v_out_dir_name VARCHAR2(30) := 'MVIEW';
v_count_object_elab NUMBER := 0;
v_cursor SYS_REFCURSOR;
v_file utl_file.file_type;
v_start INTEGER;
v_buffer VARCHAR2(1024);
v_file_name VARCHAR2(1024);
v_query CLOB;
table_or_view_does_not_exist EXCEPTION;
PRAGMA EXCEPTION_INIT(table_or_view_does_not_exist,
-00942);
BEGIN
BEGIN
EXECUTE IMMEDIATE 'DROP TABLE all_mviews_clob';
EXCEPTION
WHEN table_or_view_does_not_exist THEN
NULL;
END;
EXECUTE IMMEDIATE 'CREATE TABLE all_mviews_clob AS SELECT mview_name, to_lob(query) AS query FROM all_mviews';
OPEN v_cursor FOR q'[SELECT lower(mview_name) || '.sql' AS file_name,
query AS script
FROM all_mviews_clob]';
LOOP
FETCH v_cursor
INTO v_file_name,
v_query;
EXIT WHEN v_cursor%NOTFOUND;
v_file := utl_file.fopen(location => v_out_dir_name,
filename => v_file_name,
open_mode => 'w');
v_start := 1;
FOR i IN 1 .. ceil(dbms_lob.getlength(lob_loc => v_query) / 1024)
LOOP
v_buffer := dbms_lob.substr(lob_loc => v_query,
amount => 1024,
offset => v_start);
IF v_buffer IS NOT NULL THEN
utl_file.put(file => v_file,
buffer => v_buffer);
utl_file.fflush(file => v_file);
END IF;
v_start := v_start + 1024;
END LOOP;
utl_file.fclose(v_file);
v_count_object_elab := v_count_object_elab + 1;
END LOOP;
IF v_count_object_elab = 0 THEN
dbms_output.put_line('no mviews');
END IF;
EXCEPTION
WHEN OTHERS THEN
dbms_output.put_line('eror = ' || SQLERRM);
IF utl_file.is_open(v_file) THEN
utl_file.fclose(v_file);
END IF;
RAISE;
END;
/