Comment by namibj

What backup strategy are you implying for the case of cockroachdb? Streaming the changefeed (including timestamps) to an external append-only system while slowly and incrementally iterating through all tables using as of system time to reduce impact on active transactions and know how late this shard of a "full backup" can be inserted into the "agumented" changefeed you'd generate by interleaving these shards into the changefeed. For replay you'd use the stream from the oldest shard up to the select min(a) from (select max(timestamp_resolved) as a from changefeeds group by table) newest timestamp you know you have the transactions complete changesets for (the resolved timestamp can be periodically emitted to confirm that no further records in the same feed(/table) could have a transaction timestamp earlier than it, inducing a partial ordering).

You could replay the (combined,sorted,agumented) changefeed in-order, or shard it on the table's primary key to ensure per-key monotonicity when applying the streams in parallel threads/transactions/nodes.