AWS DynamoDB is actually quite nice for this. You set a composite (id, timestamp) index, and then you query on id and a timestamp range or "first match before o

AWS DynamoDB is actually quite nice for this. You set a composite (id, timestamp) index, and then you query on id and a timestamp range or "first match before or at timestamp x". As `zo1` mentions, though, this doesn't really seem like the kind of requirement that would necessitate obscure database technologies, especially because even in a relational database these are easily optimizable queries.