By default, auto-creation of Top Movers is disabled for new installations and upgraded Experience Analytics solutions. Top Movers must be manually enabled for each event and dimension whose changes in values you want to track.
Note: Auto-creation of Top Movers is enabled through the Portal.
A message is displayed at the top of the Top Movers tab when auto-creation of hourly and daily Top Movers is enabled. Whenever a new event or event + dimension combination is created, an hourly or daily Top Mover is created and enabled to track changes in values for the newly created event object.
Implications of auto-create
Suppose your Experience Analytics environment contains 1000 events and 500 whitelisted values in dimensions that are referenced by those events. The following sections provide some metrics on the impacts of auto-creating Top Movers and maintaining those Top Movers in your environment.
- Each event and each event + whitelisted dimension value requires one calculation.
- If the same dimension is referenced in two events, the Top Mover calculations for that dimension are performed twice.
- For 1000 events, each with 500 whitelisted values, the number of calculations is 500,000.
Each Top Mover calculation generates another row in the database. For the above data set, the number of rows that are generated per run is 500,000 new rows.
Top Mover data is retained based on the configured setting for data retention.
Top Mover (daily)-Days Retain- Number of days to retain daily Top Mover data.
365is the default setting.
Top Mover (hourly)-Days Retain- Number of days to retain hourly Top Mover data.
120is the default setting.
Top Mover data trimming must be enabled, or data is never trimmed.
For our example data set:
|Type||Rows per data collector run||Number of runs per day||Number of days||Total rows|
To estimate the time that is required to complete the calculation for the above data set of 500,000 calculations:
- By default, the number of threads that are used to complete the calculation is 4.
- With 4 threads in use, the time that is required for each calculation is approximately 1 millisecond.
- With 1 thread in use, the time that is required for each calculation is approximately 4 milliseconds.
- So, calculation for the Top Movers in this environment requires approximately 500 seconds, which is 8 minutes 20 seconds.
Resource usage goals
Note: If you auto-create hourly Top Movers for 1000 events and 500 whitelisted values, the estimated calculation time using 4 calculation threads is 8 minutes 20 seconds. These calculations are performed each hour, which means that 1/6 of the Data Collector's time is spent computing hourly Top Movers. This impact may become an issue for Data Collector to complete its other tasks.
For hourly Top Movers, the goal is to reduce calculation time to less than 5 minutes. You must balance the number of events x the number of whitelisted dimensions against the number of threads that are used during calculation and the general CPU load at the time of calculation.
By default, daily Top Movers are scheduled to be recalculated at 4:30 in the morning. You can schedule them to occur at any time.