Aug 14, 2015 3:37:00 PM by Quest Software
![]() |
Log file wait events |
Just as Oracle sessions must wait for database file I/O, they must also wait for log file I/O. Such waits occur whenever a COMMIT statement causes a write to the redo log. The session issuing the COMMIT waits on the log file sync event. When the log writer issues the I/O request, it waits on the log file parallel write event.
Both these wait events are inevitable, and often account for between 10-20% of total non-idle wait times in a healthy database.
The average wait time for a log file parallel write is an important measure. It indicates how quickly the log writer process can flush the redo buffer. It is a good indicator of the efficiency of the redo log device. Values below one-hundredth of a second are good, and values of up to five-hundredths of a second are not unusual. Values above this range may indicate contention for the redo log device.
Tags: Spotlight on Oracle Wiki
Written by Quest Software
We use cookies to improve your experience with our site. By continuing to use this site, you consent to our use of cookies. Learn more.