转抄pub帖子：

可以参考v$license中的sessions_highwater

测试了一下确实可以反映最大连接数

SQL> select * from v$license
2 ;

SESSIONS_MAX SESSIONS_WARNING SESSIONS_CURRENT SESSIONS_HIGHWATER USERS_MAX
------------ ---------------- ---------------- ------------------ ----------
0 0 27 48 0


顺便把official document 也贴出来给大家看看

V$LICENSE
This view contains information about license limits.

Column Datatype Description
SESSIONS_MAX
NUMBER
Maximum number of concurrent user sessions allowed for the instance

SESSIONS_WARNING
NUMBER
Warning limit for concurrent user sessions for the instance

SESSIONS_CURRENT
NUMBER
Current number of concurrent user sessions

SESSIONS_HIGHWATER
NUMBER
Highest number of concurrent user sessions since the instance started

USERS_MAX
NUMBER
Maximum number of named users allowed for the database