Hi,
Oracle Database Admin should know what is the database load profile and Active Session load to compare it when the complaint comes from Customer.
Oracle Database admin should find average database load profile metric values for normal times. Because When customer complain from Slowness then DBA can find actual load profile metric values and compare it from average load profile value.
You can find average Active session of database with following script.
SELECT 'Load', CASE WHEN ( ( CAST (end_time.sample_time AS DATE) - CAST (start_time.sample_time AS DATE)) * 24 * 60 * 60) = 0 THEN 0 ELSE ROUND ( ( COUNT (ash.sample_id) / ( ( CAST (end_time.sample_time AS DATE) - CAST (start_time.sample_time AS DATE)) * 24 * 60 * 60)), 2) END AS Average_Active_Session FROM (SELECT MIN (sample_time) sample_time FROM v$active_session_history ash WHERE sample_time BETWEEN SYSDATE - 1 / 1440 AND SYSDATE) start_time, (SELECT MAX (sample_time) sample_time FROM gv$active_session_history WHERE sample_time BETWEEN SYSDATE - 1 / 1440 AND SYSDATE) end_time, gv$active_session_history ash WHERE ash.sample_time BETWEEN start_time.sample_time AND end_time.sample_time GROUP BY end_time.sample_time, start_time.sample_time;
Do you want to learn Oracle Database for Beginners, then read the following articles.
https://ittutorial.org/oracle-database-19c-tutorials-for-beginners/