When a DDL and DML run into a lock in Oracle, the ORA-00054 error appears. An ALTER SESSION command allows the DDL to succeed.
When encountering an ORA-00054 error in Oracle, it indicates that the table you are attempting to access is currently locked by another query. Typically, waiting for a few minutes and reattempting the query resolves the issue as the previous session holding the lock would have completed by then.
If the error persists, there are a couple of approaches you can take to resolve it. One option is to adjust the DDL lock timeout parameter. This determines the amount of time a DDL command waits in the DML lock queue before timing out with the ORA-00054 error. This parameter was introduced in Oracle 11.1 and can be set at the instance or session level. By increasing the timeout, you provide more time for the resource to become available. However, it’s important to carefully consider the impact of increasing the timeout on system performance.
Another approach to resolve the ORA-00054 error is to identify and terminate the active session that is holding the lock on the table. This can be done by analyzing the active sessions using appropriate Oracle views. Once the session causing the lock is identified, it can be terminated, freeing up the table for further operations.
Implementing preventive measures can also help avoid encountering the ORA-00054 error in the future. Consider scheduling DDL operations during off-peak hours or planned maintenance windows to minimize conflicts. Additionally, identifying and addressing queries that continuously prevent exclusive locks can prevent this error from occurring.
Still looking for a more comprehensive understanding of how to resolve an ORA-00054 error? We recommend visiting our blog post on the topic.