The myth that query strings can't be cached

The myth that query strings can't be cached
A Madrid retailer set their CDN to bypass cache on any URL with a query string, assuming all of them were dynamic. Their cache-hit ratio sat at a miserable 48%.
The myth: query parameters mean uncacheable. The reality: 90% of their query strings were marketing tags like utm_source and fbclid, identical content with a tracking label. Each variant forced a fresh origin fetch.
What we changed: we configured the edge to ignore tracking parameters in the cache key while still passing them to analytics, and only varied cache on real parameters like ?color and ?size.
Result: cache-hit ratio jumped from 48% to 89%, Madrid product-page TTFB fell to 24ms, and origin load halved.
Not every query string is dynamic. Strip the tracking junk from your cache key.
The number that mattered: 89% cache-hit, up from 48%.