Delete after insert

[ePaul]

(This includes the changes from #171, #173, #176, #175 and builds on top. These should likely be merged first, then this one gets smaller. Implements parts of #170.)

This introduces an optional "delete-after-insert" mode. In this mode, events stored into the database will be immediately deleted.

The purpose of this is to connect the eventlog table to Fabric Event Stream's Debezium-connector (this is a Zalando-internal project), which will read the events from the logical replication log and takes care of sending them out to Nakadi.

Relevant changes:

• 171: Introduce plural method for deletion into EventLogRepository, and use it from the EventTransmissionService. (Also refactors the persist() part a bit.) (by now already in master)

• 176

• 175

• 173

• The new EventLogRepositoryImpl.persistWithIds() methods will now update the id field in the EventLog objects (implemented using the QueryStatementBatcher from ↑).
• New method EventLogRepository.persistAndDelete(), which, as the name implies, calls persist() and then delete(). In EventLogRepositoryImpl, it instead calls persistWithIds, so it actually works.
• New option nakadi-producer.delete-after-write for the spring configuration which, when true, will make EventLogWriter use persistAndDelete() instead of persist().
• Some javadoc in EventLogRepository
• Explanation in the README.

• 179

• create the publication as part of the migration scripts.

TODO:

• [ ] actually try this out – it seems to work locally in an example project I made. I was not able to deploy this to a cluster yet, as the corresponding change to FES is not yet deployed.