Third Time’s the Cache, No More

Cloudflare's Content Delivery Network (CDN) uses caching to improve website load times and reliability. However, a notable exception since 2010 was that requests with query strings were not cached until they had been requested three times. This policy aimed to reduce unnecessary disk writes for potentially unpopular queries. In March 2021, Cloudflare conducted an A/B test to evaluate the impact of caching query string requests on the first request. The results showed a minor but acceptable increase in disk writes and a modest hit rate increase of around +3% for Enterprise customers. This led to a -5% decrease in total bytes served from origin, resulting in bandwidth savings for customers. Based on these findings, Cloudflare removed the policy, allowing query string requests to be cached at first sight.