Sql

Finding slow queries # Enable the slow-query log: log_min_duration_statement Analyze plans with EXPLAIN ANALYZE Watch pg_stat_statements for the most frequent SQL Common performance killers # Full table scans: missing indexes or conditions that can’t use them Implicit type casts: functions on indexed columns disable the index N+1 queries: querying row-by-row inside a loop Large-offset pagination: OFFSET 1000000 gets slower as you page Fixes # Rewrite SQL: drive big tables with small result sets (join order) Use indexes wisely: covering and composite indexes Denormalize judiciously: precomputed summary tables Summary # SQL tuning is about understanding the execution plan. Locate the bottleneck first, then fix it — don’t blindly add indexes.