Waiting for space in the log buffer because the session is writing data into the log buffer faster than LGWR can write it out. Consider making the log buffer bigger if it is small, or moving the log files to faster disks such as striped disks.
This event occurs when another session is modifying the contents of part of the dictionary cache (or row cache). This event is often associated with high parse activity but may occur for other reasons, such as manipulation of rollback segments. V$ROWCACHE may indicate which part of the row cache is being contended.
Redo copy latches are acquired by sessions in order to write changes into the redo log buffer and by the LGWR process to ensure that there are no current writers before it copies data from the buffer to the redo log.
While trying to find an index key in an index block, Oracle noticed that the index block was being split. Oracle will wait for the split to finish and try to find the key again. Wait Time: The session will yield the CPU, so there is no actual waiting time Parameter Description rootdba The root…
Index Unique Scans returns at most 1 rowid, this means that whenever the condition in WHERE clause guarantees that only one row would be returned Oracle optimizer chooses Index Unique Scans. To summarize this, Index Unique Scan access path is used when all columns of a unique (B-tree) index or an index created as a…
Oracle Database Internal Mechanism 