设置service_names如果超过255个字符，就会报错ORA-32021: parameter value longer than 255 characters，
SQL> ALTER SYSTEM SET SERVICE_NAMES='oracleblog.org, jimmy.oracleblog.org, jimmy.he.oracleblog.org, hejianmin.oracleblog.org, he.jian.min.oracleblog.org, jimmy_he_oracleblog.org, jimmy_he_he.jian_min.oracleblog.org, jian_min_he.jimmy.oracleblog.org, jimmy.he.he_jianmin.oracleblog.org, jimmyhe_hejianmin.oracleblog.org, jimmy.he.he.jianmin.oracleblog.org' scope=both;
ALTER SYSTEM SET SERVICE_NAMES='oracleblog.org, jimmy.oracleblog.org, jimmy.he.oracleblog.org, hejianmin.oracleblog.org, he.jian.min.oracleblog.org, jimmy_he_oracleblog.org, jimmy_he_he.jian_min.oracleblog.org, jian_min_he.jimmy.oracleblog.org, jimmy.he.he_jianmin.oracleblog.org, jimmyhe_hejianmin.oracleblog.org, jimmy.he.he.jianmin.oracleblog.org' scope=both
*
ERROR at line 1:
ORA-32021: parameter value longer than 255 characters
SQL>
虽然可以通过dbms_service包来创建和修改service，使其超过255个字符，但是用这个包创建的service重启后，这些service需要dbms_service.start_service逐个拉起来，需要手工操作或者写logon trigger。
其实可以用’xxx’,'yyy’,'zzz’来替换’xxx,yyy,zzz’：
SQL> ALTER SYSTEM SET SERVICE_NAMES='oracleblog.org', 'jimmy.oracleblog.org', 'jimmy.he.oracleblog.org', 'hejianmin.oracleblog.org', 'he.jian.min.oracleblog.org', 'jimmy_he_oracleblog.org', 'jimmy_he_he.jian_min.oracleblog.org', 'jian_min_he.jimmy.oracleblog.org', 'jimmy.he.he_jianmin.oracleblog.org', 'jimmyhe_hejianmin.oracleblog.org', 'jimmy.he.he.jianmin.oracleblog.org' scope=both;
System altered.
SQL>
SQL> show parameter service_names
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
service_names string oracleblog.org, jimmy.oraclebl
og.org, jimmy.he.oracleblog.or
g, hejianmin.oracleblog.org, h
e.jian.min.oracleblog.org, jim
my_he_oracleblog.org, jimmy_he
_he.jian_min.oracleblog.org, j
ian_min_he.jimmy.oracleblog.or
g, jimmy.he.he_jianmin.oracleb
log.org, jimmyhe_hejianmin.ora
cleblog.org, jimmy.he.he.jianm
in.oracleblog.org
SQL>
SQL>
SQL>
SQL>