SELECT * FROM t_system_settings WHERE LOWER(parameter) ='CollectorRawDataSetstoKeep';

If the output of the query shows the value of CollectorRawDataSetsToKeep is 5, for example,  it means that the DB Stats job will retain the raw data of the five most recent Collection Run IDs. Anything older than that will be purged.  You can update the retention value using the  query below, replacing ? with a new value, if you want to retain the data for more days.

UPDATE t_system_settings SET value=? WHERE LOWER(parameter) = 'CollectorRawDataSetstoKeep';

UPDATE t_system_settings SET value=8 WHERE LOWER(parameter) = 'CollectorRawDataSetstoKeep';

Note that retaining Raw Data for longer periods of time will use more database space. Hence, this value needs to be set judiciously.