ORA-05031 error in Oracle Autonomous Database

 

The ORA-05031 error in Oracle Autonomous Database indicates that the SGA (System Global Area) usage for a Pluggable Database (PDB) has exceeded its limit. This issue can arise due to resource constraints or misconfiguration and can significantly impact the performance of your database, especially during resource-intensive operations like Oracle Data Pump. Here are some steps to address and prevent this issue:

mmediate Actions

1. Check Resource Usage:

   • Use the following query to monitor the SGA usage:

     
     SELECT NAME, VALUE/1024/1024 AS VALUE_MB 
     FROM V$SYSSTAT 
     WHERE NAME IN ('session pga memory', 'session pga memory max', 'session uga memory', 'session uga memory max');
     

   • Verify if the SGA_TARGET or MEMORY_TARGET settings are close to the configured limits.

2. Terminate Long-Running Sessions:

   • Identify and terminate any runaway sessions or jobs that are consuming excessive resources:

     SELECT SID, SERIAL#, PROGRAM, STATUS, SQL_ID 
     FROM V$SESSION 
     WHERE PDB = 'YOUR_PDB_NAME';
     

   • Kill the session if necessary:

     
     ALTER SYSTEM KILL SESSION 'SID,SERIAL#' IMMEDIATE;
     

3. Restart the Database (if unresponsive):

   • If the database remains unresponsive, consider restarting the PDB or the Autonomous Database instance to recover.

---

Preventive Measures

1. Adjust SGA Settings:

   • If you have control over memory allocation in your Oracle Autonomous Database (e.g., Autonomous Dedicated):
     • Increase the SGA_TARGET or adjust the workload management settings to allow higher memory usage.
     • For shared infrastructure, Oracle automatically manages resources, but you can scale up the instance to increase resource allocation.

2. Optimize Data Pump Operations:

   • Reduce memory usage during Data Pump exports/imports by setting the following parameters in your Data Pump command:

     
     expdp <username>/<password> DIRECTORY=DATA_PUMP_DIR DUMPFILE=mydump.dmp LOGFILE=mylog.log PARALLEL=1 DATA_ACCESS_METHOD=direct_path
     

     • Use a lower degree of parallelism (PARALLEL).
     • Use DATA_ACCESS_METHOD=direct_path or DATA_ACCESS_METHOD=external_table to reduce memory footprint.

3. Limit Resource Consumption:

   • Enable Resource Manager to control and prioritize workload within the PDB:

     sql
     
     EXEC DBMS_RESOURCE_MANAGER.CREATE_SIMPLE_PLAN('MY_PLAN', 'MY_DIRECTIVE');
     EXEC DBMS_RESOURCE_MANAGER.CREATE_PLAN_DIRECTIVE('MY_PLAN', 'DEFAULT_DIRECTIVE', 50, NULL, NULL);
     EXEC DBMS_RESOURCE_MANAGER.SWITCH_PLAN_FOR_PDB('MY_PLAN');
     

4. Increase Autonomous Database OCPU Count:

   • Scaling up OCPU (Oracle Compute Unit) for your Autonomous Database can increase resource availability, including memory.

5. Schedule Data Pump During Low Activity Periods:

   • Run Data Pump jobs during off-peak hours to avoid contention with other running workloads.

6. Monitor Regularly:

   • Use Oracle Cloud Infrastructure (OCI) monitoring tools to set up alerts for memory usage and potential threshold breaches.