This is a symptom of having to use two separate RPCs (and thus transactions) to add and remove tuples in processing a replication event.

There are two solutions we discussed:

1. First upsert relations, then remove any relations not including those just upserted. This could be done on the side of the sink, or the replication logic (it could just omit those tuples in that case).
2. Add a "write" RPC which can, in one transaction, do any combination of inserts, upserts and removals, and utilize this from the sink.

2 is superior because it's fully atomic (there is also no period where there is excess access) and simpler to use, but involves more work.