In Oracle, the RPAD function returns the string right-padded to the specified number of characters. RPAD accepts 2 or 3 parameters in Oracle.
MariaDB also provides the RPAD function, and since MariaDB 10.3.1 it accepts 2 or 3 parameters, so no conversion is required.
Oracle:
-- Pad string with blanks (default) SELECT RPAD('abc', 7) FROM dual; # abc (4 blanks follow) -- Pad string with * SELECT RPAD('abc', 7, '*') FROM dual; # abc****
MariaDB:
-- Pad string with blanks (default) SELECT RPAD('abc', 7); # abc (4 blanks follow) -- Pad string with * SELECT RPAD('abc', 7, '*'); # ****abc
For more information, see Oracle to MariaDB Migration.