Stale statistics cause inefficient query plans with exponentially worse performance

When autovacuum does not run ANALYZE frequently enough, query planner statistics become stale. Unlike bloat which causes linear performance degradation through extra I/O, stale statistics can cause the planner to choose exponentially inefficient query plans, drastically increasing CPU, I/O, and execution time.

Monitor n_mod_since_analyze in pg_stat_all_tables to detect tables with stale statistics. Ensure autovacuum is running regularly. For critical tables with rapidly changing data, consider running manual ANALYZE or adjusting autovacuum_analyze_threshold and autovacuum_analyze_scale_factor. Note that ANALYZE has higher overhead than VACUUM as it must rebuild statistics every time.