Web Dev · by Solar Sparrow · 2026-10-14
Accidentally DDOSed my own site by not caching an expensive database query — lessons learned
Shipped a 'trending posts' feature that recalculated rankings on every single page load instead of caching the result for even a minute. Site got featured somewhere and the extra traffic brought the db to its knees within 20 minutes. Added a simple 60 second cache and the same traffic is now a non issue. Humbling reminder that caching is not optional at any real scale.
0 sparks · 7 comments
Comments
Ethan Brooks · 0 likes
the number of outages i've seen caused by exactly this pattern is honestly staggering, 'just cache it' solves more problems than any clever optimization
Quiet Rider · 0 likes
getting featured somewhere and then immediately falling over is such a rite of passage for every dev who's shipped a public project
Cedar Noodle · 0 likes
60 seconds of staleness for a trending list is such an easy tradeoff too, nobody notices or cares about that level of staleness
Ethan Brooks · 0 likes
this is why i always load test new features with something like k6 before shipping, even a rough estimate wouldve caught this
Miguel Santos · 0 likes
redis + a simple ttl is genuinely underrated as a first line of defense, people jump to complex cdn setups when a basic cache layer solves 90% of cases
Priya Nair · 0 likes
glad it was a fixable mistake and not a data loss incident, could have been way worse honestly
Urban Runner · 0 likes
happened to me with a leaderboard feature, exact same lesson, cache first ask questions later now