The error encountered in Oracle databases indicates an attempt to access an index while it is undergoing an online build or rebuild operation. This situation arises when an index is being created or rebuilt using the `ONLINE` option, allowing concurrent access to the table while the index operation is in progress. During this process, the index’s structure is temporarily incomplete or inconsistent, preventing reliable data retrieval. As an example, a query attempting to use an index that is currently being rebuilt with the `CREATE INDEX … ONLINE` command will trigger this error.
The significance of this error lies in its potential impact on application availability. Online index builds and rebuilds are specifically designed to minimize downtime during index maintenance. This approach offers the crucial benefit of maintaining database accessibility for users and applications. The presence of this error suggests a conflict between the ongoing index operation and user queries or data modification operations. Understanding this behavior allows database administrators to schedule index maintenance efficiently and implement strategies to avoid or mitigate disruptions.
