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Don Burleson Blog 







  ORA-12751 tips

Oracle Database Tips by Donald BurlesonMarch 29, 2015

Question:  I am getting the trace file error "DDE rules only execution for: ORA 12751 ".  How do I prevent the  ORA-12751 error?  My database is locked up and I cannot open a SQL*Plus session as SYSDBA to do database diagnostics.

Answer:  If you cannot connect, you have two choices, either wait (impacting your end users) or immediately bounce the instance.  See Killing the Oracle instance and connecting to a hung database with the -prelim option.

The Oracle oerr utility show this for the ORA-12751 error:

ORA-12751:  CPU time or run time policy violation.

Cause: A piece of code ran longer than it is supposed to.

Action: If this error persists, contact Oracle Support Services.

This is a case of CPU exhaustion where the runqueue exceeds the number of CPU's on the server.  See my important notes on locating high CPU usage. 

The solution to this problem is to reduce CPU consumption by either tuning SQL statements, or by adding additional CPU's to the server.

For more details see these MOSC notes:

  • MOSC note 1478691.1 titled "Minact-scn: Useg Scan Erroring Out With Error E:12751"
  •  MOSC Note 761298.1 titled "MMON Suspended Due to ORA-12751 "cpu time or run time policy violation".
  •  MOSC Note 1291296.1 titled "ORA-12751 "cpu time or run time policy violation" in the MMON Slave Process File during Feature Usage Statistics [FUS]".

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