Question

我必须优化此查询：

SELECT DISTINCT
  sfo.entity_id,
  sfo.created_at,
  sfoa.postcode,
  sfo.customer_id
FROM sales_flat_order sfo
  JOIN sales_flat_order_address sfoa
    ON sfo.entity_id = sfoa.parent_id
WHERE sfo.entity_id IN (SELECT DISTINCT
  order_id
FROM sales_flat_order_item
WHERE sku = 'whatever'
OR sku = 'whatever1')

这会运行一段时间，我猜它是因为subselect。我知道在这里使用连接可能会加快速度，但到目前为止我还没有成功。关于如何提高速度的任何想法？

谢谢！

Answer 1

我只是将其作为额外的加入级别。

这样的事情： -

SELECT DISTINCT
      sfo.entity_id,
      sfo.created_at,
      sfoa.postcode,
      sfo.customer_id
FROM sales_flat_order sfo
INNER JOIN sales_flat_order_address sfoa
ON sfo.entity_id = sfoa.parent_id
INNER JOIN sales_flat_order_item sfoi
ON sfo.entity_id = sfoi.order_id
WHERE sku IN ('whatever', 'whatever1')

假设您在sales_flat_order_item表的sku字段上有索引，sales_flat_order表上的entity_id索引和sales_flat_order_address表上parent_id的索引，那么这应该非常快。

没有索引，几乎任何查询都会运行得很慢。

Answer 2

添加INNER JOIN sales_flat_order_item ON sales_flat_order.entity_id = sales_flat_order_item.order_id然后使用GROUP BY sfo.entity_id会有效吗？

我假设销售订单商品表中包含指向这些商品属于order_id的订单的链接。然后，您可以将sku要求添加到外部查询并删除子查询。如果您有适当的指示，这可能会加快您的查询速度。

如何加快MySQL查询速度？

2 个答案: