enq: RO - fast object reuse
Enqueue wait. Object reuse.
Additional Information​
An enqueue is a wait for a resource held by another.
enq: RO is seen when objects are being dropped or truncated.
These actions required that exclusive access is acquired, and that any dirty blocks are flushed. The checkpoint process will instruct the db writer to flush blocks for the object in question. In RAC databases, these calls will be made across the cluster.
How to reduce this wait​
As this wait is seen during drops and truncates, examine application logic to minimize concurrency.
The checkpointer process will instruct the db writer processes to flush blocks for the objects in question. This can expose bugs, so refer to Oracle Support (MOS) pages.
Additional Links​
Oracle Docs - Oracle Enqueue Names
Logical Read Blog - Oracle RO Enqueue Wait Event
IT Tutorial - Truncate Table in Oracle 19c
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