Question: I just upgraded from 10g to 11g
and I now see poor performance. My AWR report looks like this,
with high Oracle virtual circuit wait events:
Top 5 Timed Foreground
Events
Event
Waits Time(s) Avg wait (ms) % DB time Wait Class
virtual circuit wait 95,038 16,056 169
263.91 Network
What
is a virtual circuit, and why is my instance waiting on it?
Answer: First check MOSC Note 1225943.1
titled High virtual circuit waits after upgrade. A
high "virtual circuit wait" wait event has two display parameters,
P1 ("the circuit#") and P2 ("the type").
Beware, the virtual circuit wait has been associated with the
use of shared servers (The multi-threaded server, or MTS).
Oracle DOES NOT recommend using shared servers, except as a stopgap
measure because dedicated database connections are faster and
more resilient:
|
|
Get the Complete
Oracle SQL Tuning Information
The landmark book
"Advanced Oracle
SQL Tuning The Definitive Reference" is
filled with valuable information on Oracle SQL Tuning.
This book includes scripts and tools to hypercharge Oracle 11g
performance and you can
buy it
for 30% off directly from the publisher.
|