Problem
A page is reconstructed from a write-ahead log. Given a base page and a list of WAL records, apply them in LSN (log sequence number) order to reconstruct the current page; support point-in-time recovery by stopping at a target LSN.
Input / Output
- Input: a base page and an ordered list of WAL records (insert/update/delete), each with an LSN; optionally a target LSN.
- Output: the reconstructed page after applying records up to (and including) the target LSN.
Constraints
- Records must be applied strictly in LSN order.
- Support stopping at an arbitrary LSN for time-travel / PITR.
Example
- base + [insert, update, delete] in LSN order → current page; stop early at an LSN → a historical page.