This metric is used to wait for a lock on a data dictionary cache specified by "cache id". If one is running in shared mode (Parallel Server), the LCK0 is signaled to get the row cache lock for the foreground waiting on this event. The LCK0 process will get the lock asynchronously. In exclusive mode, the foreground process will try to get the lock.
The rest of the information in this section is only valid for this metric when it appears in either the Enterprise Manager Grid Control or the Enterprise Manager Database Control (if applicable).
The following table shows how often the metric's value is collected and compared against the default thresholds. The 'Consecutive Number of Occurrences Preceding Notification' column indicates the consecutive number of times the comparison against thresholds should hold TRUE before an alert is generated.
|
Target Version |
Evaluation and Collection Frequency |
Upload Frequency |
Operator |
Default Warning Threshold |
Default Critical Threshold |
Consecutive Number of Occurrences Preceding Notification |
Alert Text |
|
pre-10g |
Every Minute |
After Every Sample |
> |
20 |
Not Defined |
3 |
%value%%% of service time is spent waiting on the 'row cache lock' event. |
(DeltaRowCacheLockTime/DeltaServiceTime)*100 where:
DeltaRowCacheLockTime: difference of 'sum of time waited for sessions of foreground processes on the 'row cache lock' event' between sample end and start
DeltaServiceTime: difference of 'sum of time waited for sessions of foreground processes on events not in IdleEvents + sum of 'CPU used when call started' for sessions of foreground processes' between sample end and start
See Idle Events
If this event shows up a lot, consider increasing the shared pool so that more data dictionary can be cached.
Related Topics
About Alerts
About the Metric Detail Page
Editing Thresholds
Understanding Line Charts
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