Why does my query drop from 3ms to 4 seconds on Tuesday with no deploy?
機会
PostgreSQL's query planner re-evaluates execution plans whenever table statistics change, which happens asynchronously through autovacuum and ANALYZE, independent of any code deployment. A batch import, a routine vacuum after deletion, or a gradual shift in data distribution can flip an index scan to a sequential scan overnight, turning a 3ms query into a 4-second one with no error emitted and no deployment in the history. These regressions are invisible in CI because they are driven by statistics state, not code state, and no standard test harness captures plans across different statistics snapshots. Pganalyze and similar tools detect plan flips after they occur in production, but there is no upstream gate that tests query plan stability before a schema change or data migration ships. PostgreSQL proposed the pg_plan_advice contrib module in October 2025 to let operators hint or pin plan
重要な理由
Silent query plan regressions are one of the most common causes of unexplained production latency spikes and they remain undetectable until a user reports slowness.
機会をどう評価するか
Opportunity Scoreは測定値ではなく、私自身の見解です。どれほど痛みを伴うか、どれほど頻繁に影響を与えるか、そして今日時点で解決策がいかに少ないか。スコアが高いほど、構築する価値が高いと私は考えています。
それが現れたときにどれほどの痛みをもたらすか。
実際にどれほど頻繁に人々がそれに直面するか。
今日時点で、それに対する優れたツールがいかに少ないか。