With durable history, we always write the latest version to disk. This causes us to duplicate the on-disk value on the update chain for the in-memory database if there are older versions we cannot discard.

U@20 -> U@10

Suppose we have an insert list like above and the oldest timestamp is 5, after reconciliation, we will have

U@20 -> U@10 on the update chain and disk value U@20.

We consume more memory after reconciliation.