Apply Oracle Functions to Individual numeric characters in a string

Question

I'm trying to apply MOD function and some arithmetic to each and every numeric character with-in a string. Maximum length of the string is 30 characters, and its variable length. When I try the traditional for loop, my execution time increases drastically. Here are some details:
If my string is: abc1234X-23J, I need to keep the alphabets and special characters as is, multiply each numeric by 5 add 3, apply a MOD of 10. I've done this in a function like this:
CREATE OR REPLACE FUNCTION Test1(i_Text IN VARCHAR2) RETURN VARCHAR2 IS
V_Output VARCHAR2(30) := '';
BEGIN
FOR I IN 1 .. LENGTH(i_Text) LOOP
IF SUBSTR(i_Text, I, 1) IN ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9') THEN
V_Output := V_Output || TO_CHAR(MOD((TO_NUMBER(SUBSTR(i_Text, I, 1)) * 5) + 3, 10));
ELSE
V_Output := V_Output ||SUBSTR(i_Text, I, 1);
END IF;
END LOOP;
RETURN V_Output;
EXCEPTION WHEN OTHERS
RETURN NULL;
END;
I need to apply this function to approximately. 4 columns, data volume is huge. I tried with 2.5 M records, in INSERT ... SELECT option, it takes 17 seconds without this function and around 6 minutes when I use this function. This is just a sample data, I would like this task to be completed with-in 30 seconds. Is there any way I can change my function or use any other option to get better performance?
Note: I tried REGEXP_REPLACE - this didnt help me, increased my execution time - I had to use native dynamic sql in this case
Tried with decode - this also didnt help.
Any expert advice is appreciated.
Thanks in advance.

Answer 1

SQL> select mod((l*5)+3,10), l from (select level - 1 l from dual connect by level <= 10);
MOD((L*5)+3,10)          L
              3          0
              8          1
              3          2
              8          3
              3          4
              8          5
              3          6
              8          7
              3          8
              8          9
SQL> select translate('abc1234X-23J,','0123456789','3838383838') FROM DUAL;
TRANSLATE('AB
abc8383X-38J,Hope this helps
cheers
Raj
Message was edited by: code formatting applied
s.rajaram