ORIGINAL COMPANY-CONTEXT PRACTICE
Reconstruct a statement as of its cutoff
Original practice scenario inspired by Commonwealth Bank of Australia's public business context; this is not a reported interview question or a description of its internal systems. A synthetic account ledger has booking_time, effective_day, amount_cents, and correction relationships. Explain how to produce a reproducible statement for a historical cutoff without accidentally including later-known corrections.
Written for independent practice using company context; this is not a verified question from a company interview.
A REASONED APPROACH
Model answer.
Specify whether the statement represents knowledge at publication or a later restatement. Booking time controls what was known; effective day controls the business period to which an entry belongs.
Work through it
- Filter entries to booking_time at or before the recorded statement cutoff, then apply the documented effective-day range. Keep both timestamps in the audit trail.
- Aggregate signed ledger entries, treating reversals and corrections according to their explicit relationships. Do not silently overwrite original posted amounts.
- Persist statement parameters and source watermark. Test a late correction effective in the earlier month, an exact cutoff boundary, and a reversal arriving after publication.
Tradeoffs to discuss
- Immutable statement snapshots improve reproducibility but require a separate restatement process when later information changes the period.
Common pitfalls
- Filtering only by effective day leaks later knowledge into the original statement.
- Summing both an overwritten value and its adjustment can double-count the correction.