You need to pay a supplier in Tokyo. You open your banking app in New York, type in the supplier’s bank details, and hit send for $10,000. Three business days later, the supplier confirms they received the money. But they…
We had a performance problem. One of the most frequently accessed pieces of data was being read far more often than it changed. The database was handling a large number of repeated reads. The obvious solution was caching. We introduced…
In a microservices architecture, a downstream HTTP failure typically results in a degraded user experience—a missing recommendation feed or a failed profile image load. The system logs an error, returns a fallback, and moves on. In an acquiring gateway, a…
A monolithic relational database hosting a multi-million-row account_balances table eventually hits a hard physical ceiling. As the dataset outgrows the available RAM, the database buffer pool begins to thrash. B-Tree index traversals require excessive disk I/O, and row-level lock management…
You are checking out of an online store. Below the familiar “Visa” and “Apple Pay” buttons is a new option: “Pay with Bank.” You click it. You are redirected away from the merchant and into a secure portal hosted by…
We had a performance problem. One part of the application was doing too much work during a synchronous request. The obvious solution was to move the work out of the request path. Instead of: we changed the flow to: The…
