The Reports Switch SYS Form Answers Refresh is used to load the data into dm table dm_cached_form_ans.
Full Refresh
If the switch value is set to Full Refresh, the dm_cached_form_ans table is truncated and loaded on every populate job run.
Monitor Changes
If the switch value is set to Monitor Changes, an incremental load takes place. Any data in dm_cached_form_ans which has been modified between previous pop job run and the current run will be deleted, along with any records where the data no longer exists in the table dm_template_question_versions. The data for each form answer type (long text ,short text, date, numeric, Boolean...) which has been added/modified between the previous and current population will then be inserted.
If number of rows in dm_cached_form_ans < 100000 then, then the populate will force a Full Refresh (truncate and load dm_cached_form_ans), including when the switch is set to Monitor Changes.
To check the selected option, access the Reporting Database, and run the following script:
SELECT *
FROM report_switch_mappings
WHERE switch_name = 'SYS Form Answers Refresh'