Ora-12801 parallel query server failed to start is an error that prevents the user from properly running Oracle's parallel query. This error occurs when the user has attempted to start the instance in the wrong parallel mode. The error can be caused by a combination of different factors, including the presence of incompatible components in the environment, improper parameter settings, or a lack of memory. This document will explain how to troubleshoot and resolve this error.
Prerequisites
Before attempting to fix the ORA-12801 error, make sure the user has the following items:
- Access to the Oracle Error Code Documentation
- Access to Oracle Support
- Understanding of the user's environment
- Knowledge of the user's query server
- Knowledge of Oracle parallel query
Identifying the Cause of ORA-12801
The first step in fixing this error is to identify the root cause of the issue. To determine the cause, the user should go through the following steps:
- Review the Oracle error message for clues about the cause of the issue.
- Execute the query again with different system parameters.
- If the same ORA-12801 error appears, continue troubleshooting by examining applicable components within the user's environment.
- Examine the Oracle documents related to parallel query server issues.
Troubleshooting
Once the user has identified the cause of the ORA-12801 error, they should investigate the following common causes and troubleshooting steps:
Incompatible Components
If incompatible components (such as another query server or version) are present in the user's environment, the ORA-12801 may occur. To resolve this issue, the user should detect and remove any incompatible components from their environment.
Improper Parameter Settings
Incorrect parameter settings can also cause the ORA-12801 error. The user should investigate the parameters related to the parallel query server, and modify any settings that are incorrect.
Insufficient Memory
In some cases, the ORA-12801 error is caused by a lack of available memory. To resolve this issue, the user should ensure that the system has adequate memory resources allocated for the parallel query server.
FAQ
Q: How can I detect incompatible components in my environment?
A: The user should use Oracle Support resources to detect and remove any incompatible components from the user's environment.
Q: What should I do if I have insufficient memory?
A: To resolve this issue, the user should ensure that the system has adequate memory resources allocated for the parallel query server.
Q: What parameters related to the parallel query server should I investigate?
A: Parameters related to the parallel query server include the parameter DOP (degree of parallelization), and the parameters SGS_MAX_SERVERS, SGS_GOVERNANCE_LIMIT, and SGS_ENDDATE.