Axiom Pay's batch ledger settled overnight. Their largest merchants wanted funds in minutes. We rebuilt the core on event sourcing and moved 2.1 billion historical records without a single hour of downtime.
From overnight batch to a 42-second median, measured end to end.
Across an eleven-month migration covering 2.1 billion records.
Peak-verified at three times the previous system's ceiling.
The regulator's event-history request was satisfied at first review.
The existing ledger was a nightly batch process built in 2009. It could not settle intraday, reconciliation errors were found a day late, and a regulator had asked for an auditable event history the system could not produce. Every previous attempt to replace it had been abandoned because the cutover risk was judged too high.
We introduced an append-only event store alongside the existing ledger and dual-wrote to both for four months. The old system stayed authoritative while we proved the new one matched it, transaction for transaction.
An automated reconciler compared both ledgers every fifteen minutes and alerted on any divergence beyond a cent. By month six it had run clean for 43 consecutive days, which is what made the cutover decision defensible.
2.1 billion historical records were replayed into the event store in throttled batches during off-peak windows, verified with checksums per merchant per day.
Merchants moved in cohorts by volume, smallest first, each with an instant rollback flag. The largest merchant moved last, ten months in, by which point the path was thoroughly worn.
“Three consultancies told us this migration was impossible without a weekend freeze. Cymbiote spent the first month telling us exactly why those attempts had failed, then spent ten more proving their alternative worked before they asked us to trust it.”
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