query-missing-indexes

## 在 WHERE 和 JOIN 列上添加索引 在未索引的列上进行过滤或连接会导致全表扫描，随着表规模的增长，性能会呈指数级下降。 **错误（大表上的顺序扫描）：** sql -- customer_id 上没有索引导致全表扫描 select * from orders where customer_id = 123; -- EXPLAIN 显示：Seq Scan on orders (cost=0.00..25000.00 rows=100 width=85) **正确（索引扫描）：** sql -- 在频繁过滤的列上创建索引 create index orders_customer_id_idx on orders (customer_id); select * from orders where customer_id = 123; -- EXPLAIN 显示：Index Scan using orders_customer_id_idx (cost=0.42..8.44 rows=100 width=85) 对于 JOIN 列，始终索引外键侧： sql -- 索引引用列 create index orders_customer_id_idx on orders (customer_id); select c.name, o.total from customers c join orders o on o.customer_id = c.id; 参考：[查询优化](https://supabase.com/docs/guides/database/query-optimization)