Updated at: May 4, 2017
SELECT * FROM V$EVENT_NAME;
-- https://github.com/genghuiluo/legacy/blob/master/oracle_dba_scripts/wait_event.sql SELECT s.sid, s.serial#, sql.sql_text, sql.sql_fulltext, sw.event AS wait_event FROM v$session s JOIN v$sql sql ON s.sql_address = sql.address JOIN v$session_wait sw ON s.sid = sw.sid;
general wait events:
Generally SQLNet message from client means Oracle is just waiting on some work to do. The SQLNet message from client means that you have a session connected and Oracle is waiting for a command so it can do something.
The SQL*Net message to client may indicate a network-related issue that causes clients too long to get data from the database server. Thus, it can be a TCP issue, but it is not limited to that.
When you run full table scan (or a parallel query full-table scan), you will see direct path reads wait event. But in the beginning you will also see the enq: ko - fast object checkpoint wait event. This will checkpoint any blocks that belong to the object you are doing direct path read so that latest change goes into the datafile.
-- SGA memory allocation select * from v$sgainfo