Time-spent monitor element hierarchy
The information in many time-spent monitor elements is rolled up in more general monitor elements.
For example, individual wait time elements, such as that for the time spent waiting to receive the information in the next buffer from a table queue (fcm_tq_recv_wait_time) and time spent waiting for an FCM reply message (fcm_message_recv_wait_time) are both included in overall fcm_recv_wait_time element. The hierarchical organization of time-spent monitor element makes it possible to choose the element with the most appropriate level of specificity for your needs.
Dimensions and perspectives for viewing time-spent monitor elements
There are different ways that you can look at the hierarchies of time-spent monitor elements. One way is to look at them from the viewpoint of the system as a whole; you can also look at them in the context of specific activities within the system.
The system-level view or system dimension includes elements that you can use to see what the system is doing as a whole. You can also use elements in the system dimension to view time-spent information for specific workloads.
The activity-level view or activity dimension includes elements that you can use to see which specific activities the system is spending time on, such as the execution of SQL statements. All monitor elements in the activity dimension are included in the higher-level system dimension.
- Component processing times as compared to wait times
- Component elapsed times as compared to component processing times
In the second perspective, component elapsed times are a superset of component processing times. For example, for a logical component of the database such as that component that performs commits, the total amount of commit processing time, as reported by the total_commit_proc_time monitor element, is included in the overall elapsed time for the commit, as reported by the total_commit_time monitor element. The difference between the total elapsed time and the total processing time is made up of miscellaneous wait or processing times that are not individually tracked by the component elapsed time monitor element.
Viewing component elapsed times relative to wait times is not meaningful, because component elapsed times already include wait times that are incurred as part of the elapsed time in that part of the system. If you created a pie chart consisting of both component elapsed times and wait times, it would not be an accurate representation of the time that is spent in your system because you would be double-counting the various types of wait times.
The sections that follow describe the various dimensions (system and activity) and perspectives (component processing, wait times and component elapsed, and component processing times) from which you can view the information in time-spent monitor elements.
System dimension
Figure 1 shows an overall view of how the monitor elements for wait time and component processing time relate to one another, as viewed from the system dimension.
- One that reports the total amount of processing time in a component or stage of processing
- One that reports the overall elapsed time that is spent in the component. This overall time includes the processing time for the component and any other processing or wait times that might be involved.
Activity dimension
Figure 3 shows the monitor elements that you can view for activities from the perspective of wait times as compared to component processing times.Figure 4 shows the monitor elements that you can view for activities from the perspective of component elapsed times, which include component processing times.