This introduces an expiry date (default: 14 days from insert date) and
adjust the service-maintenance script to delete jobs that are older than
the expiration date.
Define supported job type names as constants and use them in all places,
instead of string literals.
There are multiple benefits of this approach. Using constants removed
the room for typos in the string literals. One can use autocompletion in
IDE for job types. Using constant makes it easier to find all references
where it is used and thus all places that are handling a specific job
type.
Call vacuum analyze after each chunk of updates, and dump vacuum stats
at the beginning and end of the db cleanup.
Nulling results can increase size on disk, but calling vacuum analyze
will free up space within the table (not on disk) and reuse the space
for new inserts and updates.
Instead of deleting records, delete the results from the manifest and
depsolve jobs. This redacts sensitive data which the manifest can
contain, and this conserves space.
