What does the rollback rate in the Oracle Sessions dashboard represent? (4377042)

In brief, the rollback rate is the rate per second of rollbacks during the current sampling period.

It typically refers to the number of rollback segments or undo records being processed per second. This is important for monitoring performance, especially in high-transaction environments, as it can indicate how well the database is managing undo data.

Our specific calculations are proprietary, but the sessions dashboard collects all of the data from the running sessions.

At a high level, the rollback count is derived from the "user rollbacks" value which is aggregated data from V$SESSTAT. This field reflects the total number of rollbacks for each session during its lifetime.
 

Re: https://docs.oracle.com/en/database/oracle/oracle-database/21/refrn/statistics-descriptions-2.html 

To calculate the rollback rate (rollbacks per second), it reruns this sessions collection query on set frequency. The on-demand refresh Sessions panel refresh rate for example is 30 seconds. The agent then computes the difference in rollback counts over the elapsed time and this is combined for all of the sessions.