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摘要： The session is looking for a consistent read version of data but cannot find it in the local cache. The local instance has made a request to other RAC instances for the data and is waiting on its retu... 阅读全文

摘要： When a request for rows from a table is issued, Oracle may determine through the cost-based optimizer, which index access path is best for finding rows in a table. During this index lookup process, if... 阅读全文

摘要： Waits on 'db file sequential read' normally occur during index lookups when the block is not in memory and must be read from disk. They are generally considered a 'good' read unless the index being us... 阅读全文

摘要： Sometimes related to sorting operations, check to see if occurring primarily in temp tablespaces. During Direct Path operations the data is asynchronously read from the database files. At some point t... 阅读全文

摘要： Often related to sorting operations, check to see if occurring primarily in temp tablespaces.Solutions1) Reading from temp tablespacesIf the database parameter workarea_size_policy = AUTO:Increase the... 阅读全文

摘要： Direct path writes allow a session to queue an I/O write request and continue processing while the OS handles the I/O. If the session needs to know if an outstanding write is complete then it waits on... 阅读全文

摘要： During Direct Path operations, the data is asynchronously written to the database files. At some stage the session needs to make sure that all outstanding asynchronous I/O have been completed to disk.... 阅读全文

摘要： Waits on High Water enqueue occur when allocating space beyond the high water mark of a segment during insert operations. Also, this wait occurs when reclaiming free space in lob segments after delete... 阅读全文

摘要： Sessions waiting on this event are waiting on locks held during materialized view operations (such as refresh, alter) to prevent concurrent operations on the same materialized view.SolutionsA material... 阅读全文

摘要： New to Oracle 10g is the individual tracking of over 180 specific enqueues or internal Oracle locking mechanisms. One of these is the RO enqueue wait event for Object Reuse, and is used to synchronize... 阅读全文