Leverage transactional features to invalidate + update pending data

[fracek]

Is your feature request related to a problem? Please describe.

At the moment, data generated by pending blocks is first invalidated (delete) and then reinserted. This results in a fraction of a second when this data is missing.

Describe the solution you'd like

Invalidation + update should be done in the same db transaction (if the sink is a db).

• Change the db trait to have a flag in handle_data that signals if the sink implementation should invalidate data before insertion
• Change connector code to not invalidate data in between pending blocks (or between pending -> accepted), but signal this to the sink.

Describe alternatives you've considered

We could introduce the concept of transaction to the sink (e.g. a begin_txn, commit_txn method) and then have handle_data, handle_invalidate be methods on the transaction object. This is conceptually more correct, but it will introduce more complex types.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the six months. It will be closed in 2 weeks if no further activity occurs. Please feel free to leave a comment if you believe the issue is still relevant.

[fracek]

Another option is to add a replace_data method to the sink with a default implementation that calls handle_invalidate and handle_data, then specific implementations can override it to use transactions.