Allow publication completion to delete database entries instead of setting completion date

[odrotbohm]

Currently, an event publication is marked as completed by updating the corresponding row in the database with a completion date. This causes the content of that table to grow over the lifecycle of an application. Developers have to manually purge old entries using the CompletedEventPublications abstraction.

It would be nice if developers could opt into a “complete by deletion” mode, in which, instead of setting a completion date, an event publication row would be deleted instead.

Required steps

• Introduce a configuration property spring.modulith.events.completion-strategy with two values: UPDATE (current algorithm) and DELETE (new algorithm).
• EventPublicationRepository implementations would inspect that configuration property to alter their database interaction accordingly
  • Lookup queries would have to alter their where clause
  • Completion queries would need to change from an UPDATE to a DELETE.

I don't think we'd need to tweak the schema initialization functionality, which could theoretically create an optimized schema if the new algorithm is activated. Users usually roll their own schema initialization scripts in production anyway.