Why oracle function return 4000 characters ?

Question

Dear All
When I write any function to get some return value in a query, its width is set to 4000. Moreover, when i write the same query to create any LOV, it gives an error that record group field cannot be greater than 2000. Where the actual width of this field is 200 characters.
Why function always returns 4000 characters?
Regards
Edited by: OraLearner on Dec 1, 2010 11:47 AM

Answer 1

Because the maximum of a varchar2 in SQL is 4000 and you have no dimension in your function:
SQL> r
  1  create or replace function myfunc(inMaxVal in number) return varchar2 is
  2    vRet varchar2(32000);
  3  begin
  4    for i in 1..inMaxVal loop
  5      vRet := vRet || '1';
  6    end loop;
  7    return vRet;
  8* end;
Function created.
SQL> select myfunc(4001) from dual;
select myfunc(4001) from dual
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at "SCOTT.MYFUNC", line 7
SQL> select myfunc(4000) from dual;
MYFUNC(4000)
1111111111111111111111111111111111111111111111111111
1111111111111111111111111111111111111111111111111111so the SQL Engine have to assume your function returns 4000 bytes. If you use this function in PL/SQL it can be up to 32767 bytes:
SQL> r
  1  begin
  2  dbms_output.put_line(substr(myfunc(4002), 1,255));
  3* end;
11111111111111111111111111111111111111111111111111111111
PL/SQL procedure successfully completed.cheers