How can parallel query being executed identified?
When Parallel Query serialised is alarm go to the Sessions Drilldown Parallel Query Sessions tab but no session and information in the Parallel Query
Sessions grid is returned. Could there be something wrong with the settings?
The alarm Parallel serialized on the Spotlight Home page reflects sql that cannot be processed in parallel. This normally happens when there are insufficient parallel servers due to other sessions using all the parallel servers available. If there is sufficient parallel server you would need to examine the individual sql statements to try to work out why.
A very trival example if the oracle parameter parallel_max_servers = 3 and I run the following sql
Select /*+ PARALLEL(dba_objects, 2) */ * from dba_objects;
Select /*+ PARALLEL(dba_objects, 2)*/ * from dba_objects; The Serialised Alarm will be triggered.
Now goto the Parallel Query Sessions drilldown and you can see the three sql entries in the grid; only three as that is the max allowed by the oracle parameter set to 3. The fourth is not listed as it is not running in parallel, rather it is serialized.
There is no way to discover what sql query (or its session) was forced to serialise.
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So the most likely reasonno entries are seenin the drilldown grid is the sql is not working parallel. The grid only show the sql that are running in parallel you may consider the oracle parameter parallel_max_servers and/or check if other sessions on the database are using the all the parallel servers
