In WiredTiger a page can be split by checkpoint, however the in-memory version of that page remains the same. If the in-memory page is dirtied prior to eviction then we will, at some point reconcile the page again, splitting it again, in a similar fashion to before.

This is somewhat expensive, and in the disagg world also reduces the number of page deltas generated. Effectively if a page is has been split into multiple blocks, we would ideally realize that split in memory prior to allowing modifications on the page, thus the subsequent modification would be written as a delta.

To achieve this we should aim to urgently scrub pages that are reconciled as multi-page splits.