This metric signifies that a database user is blocking at least one other user from performing an action, such as updating a table. An alert is generated if the number of consecutive blocking occurrences reaches the specified value.
Note: The catblock.sql script needs to be run on the managed database prior to using the User Blocks test. This script creates some additional tables, view, and public synonyms that are required by the User Blocks test.
Note: Unlike most metrics, which accept thresholds as real numbers, this metric can only accept an integer as a threshold.
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 5 Minutes |
Not Uploaded |
> |
0 |
Not Defined |
3 |
Session %sid% blocking %value% other sessions. |
|
Target Version |
Server Evaluation Frequency |
Collection Frequency |
Upload Frequency |
Operator |
Default Warning Threshold |
Default Critical Threshold |
Consecutive Number of Occurrences Preceding Notification |
Alert Text |
|
10.1.0.x; 10.2.0.x; 11.1.0.x; 11.2.0.x |
Every Minute |
Not Defined |
After Every Sample |
> |
0 |
Not Defined |
15 |
Generated By Database Server |
For this metric you can set different warning and critical threshold values for each "Blocking Session ID" object.
If warning or critical threshold values are currently set for any "Blocking Session ID" object, those thresholds can be viewed on the Metric Detail page for this metric.
To specify or change warning or critical threshold values for each "Blocking Session ID" object, use the Edit Thresholds page. See Editing Thresholds for information on accessing the Edit Thresholds page.
SELECT SUM(num_blocked)
FROM (SELECT id1, id2, MAX(DECODE(block, 1, sid, 0)) blocking_sid,
SUM(DECODE(request, 0, 0, 1)) num_blocked
FROM v$lock
WHERE block = 1 OR request>0
GROUP BY id1, id2)
GROUP BY blocking SID
Either have user who is blocking other users rollback the transaction, or wait until the blocking transaction has been committed.
Related Topics
About Alerts
About the Metric Detail Page
Editing Thresholds
Understanding Line Charts
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