postgres SQL 优化 查找慢 SQL 使用 pg_stats_statements 查找 开启 auto_explain 使用 auto_explain mode, 开启以下选项 log_nested_statements log_min_duration Index Tuning pg_stats... 相关视图 sql SELECT relname, seq_scan - idx_scan AS too_much_seq, CASE WHEN seq_scan - coalesce(idx_scan, 0) > 0 THEN 'Missing Index?' ELSE 'OK' END, pg_relation_size(relname::regclass) AS rel_size, seq_scan, idx_scan FROM pg_stat_all_tables WHERE schemaname = 'public' AND pg_relation_size(relname::regclass) > 80000 ORDER BY too_much_seq DESC; 没有使用索引 SELECT indexrelid::regclass as index, relid::regclass as table, 'DROP INDEX ' || indexrelid: