Exercise: Migrating a Live Payments Table

1. The Table, and What Has to Change

A payments service has one table that has been in production for four years. It holds eleven million rows, takes roughly four hundred writes a second at peak, and every row in it is money that somebody will eventually audit.

CREATE TABLE payments (
  id            BIGSERIAL PRIMARY KEY,
  account_id    BIGINT      NOT NULL,
  amount_cents  INTEGER     NOT NULL,
  status        VARCHAR(32) NOT NULL,
  card_last4    VARCHAR(4),
  card_brand    VARCHAR(32),
  created_at    TIMESTAMPTZ NOT NULL
);