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Don Burleson Blog 







ORA-12805: parallel query server died unexpectedly

Oracle Database Tips by Donald BurlesonMay 5, 2016

Question: What causes this parallel query error?

ORA-12805: parallel query server died unexpectedly

How do I fix the ORA-12805 error?

Answer:  The oerr utility shows this for the ORA-12805 error:

ORA-12805: parallel query server died unexpectedly.

Cause: The PMON process is cleaning up the process because a parallel query server terminated unexpectedly.

Action: Check for operating system errors and retry the statement. If this problem persists, contact customer support.

This is an OS error and you need to check your OS system logs (/etc/syslog) to find the reason why the parallel query process terminated.  You may also see a Oracle trace file generated, and you should always check your Oracle alert log for any associated messages.

Also, changing parallel_degree_policy=manual can fix the ORA-12805 error.

This error can also occur if a user killed a parallel query slave (factotum) process.  Sometimes, increasing the value for parallel_max_servers will fix the ORA-12805 error.

In Oracle 11.1 there is a known bug that causes the ORA-12805 error.  This can be addressed by employing the following workaround to make GUI queries not parallel by setting db_gui_dop to 1:

$ execsql config_set_value wi_core db_gui_dop 1

However, Oracle recommends that you upgrade to database version and download and install patch 13582702.

MOSC Reference:  Bug 9930649 - Parallel Query fails with ORA-12805 ( Time-out waiting for slave Join Ack ) (Doc ID 9930649.8)

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