The current PurgeHistory Stored Procedures are a great way to maintain the DB, however, I would like to suggest some additional parameters to allow for a more finegrain usage:
1) Parameter to toggle Flow Input/Output Deletion
The OO API to purge the Execution Summary has inputs to toggle the Deletion of Flow Inputs and Flow Outputs. The SQL scripts should have this option as well. Use Case: You want to delete only the detailed info in the step log but not the input/outputs of the flow due to retention policies.
2) Parameter to Purge Particular Runs
The SQL procedure should have a parameter that allows me to trigger the purging for given Run IDs, irregardless of the given timestamp. This option would probably not be used in a scheduled job but is very usefull for ad-hoc purging. Use Case: Due to an unforeseen error in the flow logic, a flow runs a very long loop very often, creating unnecessary data. I immediately want to purge this new data and not wait for our scheduled purge.