CPU wait events take place when the session is waiting in the system's run queue to be granted for CPU cycles. The length of these wait events (the amount of time spent) depends upon the number of concurrent processes and threads requesting CPU time.
Because a cursor points to a currently selected set of records, they can be used by only one connection at a time. However, the compiled plan to which the cursor is linked can be used simultaneously by multiple connections.
Using Data Guard’s set of services for creating, maintaining, managing, and monitoring one or more standby databases, enables production Oracle databases to survive disasters and data corruptions. These standby databases are then maintained as transactionally-consistent copies of the production database. If the production database is unavailable due to outage (either planned or unplanned), these copies enable Data Guard to switch any standby database to the production role, thereby minimizing the downtime associated with the outage.
A Dataflow displays the current level of activity. As the rate of data transfer increases, so too does the speed of the flow. If the statistic that the flow represents moves to another threshold, the flow may change color. The combination of movement and color makes it easy to spot congested areas. A graph above the flow shows how the load has varied over time.