Symptoms: Users report that some process has stopped or timed-out.
This alert means that some unidentified query has created a block and it raises an alert about other queries that are dependent on the blocked one(s).
Expected behavior :
There is no standard setting for this alert.
One or more queries cannot complete, due to their dependency on a higher-level query that is blocking a required resource. This may cause disruption to performance to specific users. See also here.
Recommended action :
Examine all currently running queries, especially ones that appear to have remained active for unexpected lengths.
Investigate the cause of the top-level query blocking.
Investigate the code of the query, and if necessary terminate.
Once the issue there is resolved, this alert should have been resolved automatically.
Blocking occurs when one process holds a lock on a specific resource and a second one attempts to acquire a conflicting lock type on the same resource. Tracking the history of the block via the AimBetter Profiler gives a clear analysis of the whole query execution picture, enabling you to take the correct action.
This alert is informative, indicating that some higher-level action to resolve a different blocked query is required.