High water mark sessions Tips Oracle Database Tips by Donald Burleson

Question: How to I find the high water mark of sessions since database startup time?  I have Oracle 11.2 and I want to know the highest amount of connected sessions.

Answer:  First, see my notes on table high water mark and  and AWR: high water mark of sessions.

Cumulative high water marks for sessions reside in the v$license and v$sysstat views. 

select 
   name, 
   value 
from 
   v$sysstat 
where 
   name like '%logon%';

select 
   sessions_current, 
   sessions_highwater 
from 
   v$license; 

NAME VALUE
--------------------- ----------
logons cumulative     68,784,884
logons current               179


SESSIONS_CURRENT SESSIONS_HIGHWATER
---------------- ------------------
101              498

Also, see this script to display high water mark data:

prompt
prompt *******************************************
prompt Display login high water mark
prompt ******************************************* 

col c1 heading 'Name'  format a40
col c2 heading 'Value' format 999,999,999

select 
   name  c1, 
   value c2
from 
   v$sysstat 
where 
   name like '%logon%';

prompt
prompt *******************************************
prompt Display sessions high water mark
prompt ******************************************* 

select 
   sessions_current, 
   sessions_highwater 
from 
   v$license; 

prompt
prompt *******************************************
prompt Display system high water marks
prompt ******************************************* 

set lines 80

col c1 heading 'Name'            format a58
col c2 heading 'High|Water|Mark' format 999,999,999,999,999

select 
   description c1,
   highwater   c2
from
   dba_high_water_mark_statistics
where
   highwater <> 0;

These are great scripts to display the high water mark for connected sessions in Oracle.