Articles

One product page, 201 queries: fixing N+1 and making it visible in review

The N+1 query problem, answered end to end — why 201 fast queries add up to 9 seconds while the slow log stays empty, the fix ladder from eager loading to batch loaders and counter caches, the traps (cartesian joins, per-parent limits, huge IN lists), and how to turn query count from a runtime accident into something CI fails on.