Which events would you consider from the output for further investigation?

You want to review a summary of all the wait events in an instance since it started over a month ago.
You issued the following query:
SQL>SELECT event, total_waits, time_waited, average_wait
FROM V$SYSTEM_EVENT
ORDER BY time_waited DESC;
View the Exhibit and examine a portion of the output from the above query.
Which events would you consider from the output for further investigation? (Choose all that apply.)
Exhibit:

You want to review a summary of all the wait events in an instance since it started over a month ago.
You issued the following query:

SQL>SELECT event, total_waits, time_waited, average_wait
FROM V$SYSTEM_EVENT
ORDER BY time_waited DESC;

View the Exhibit and examine a portion of the output from the above query.

Which events would you consider from the output for further investigation? (Choose all that apply.)

A.
log file sync

B.
rdbms ipc message

C.
SQL*Net message from client

D.
log file switch (checkpoint incomplete)

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Rodge

Rodge

Answer given is correct. Reasons being

Log File Sync – this is essentially the wait time between a user issuing a commit and control being returned to the session. The wait time shown is quite long.
log file switch (checkpoint incomplete) – indicates that Oracle is attempting to reuse a logfile but it is currently still the current logfile. So redo generation will stop until the file is cleared. This is a very significant issue.

“rdbms ipc message” and “SQL*Net message from client” – both essentially idle waits. Not worth investigating, outside of very specific scenarios.

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