Question

我正在绞尽脑汁试图弄清楚为什么这个查询需要这么长时间。它可以正常工作，但是当我稍后将此查询与另一个查询连接时，我收到了500内部服务器错误“。任何明显的想法是什么导致此查询超时？链接的所有表都运行得很快。

SELECT
`ORDERS`.`Order ID` AS `Order ID`,
`ORDERS`.`Item ID` AS `Item ID`,
`qb_group`.`product` AS `product`,
`qb_group`.`qb_product` AS `qb_product`,
`qb_group`.`description` AS `description`,
`ORDERS`.`Ordered` AS `Ordered`,
`qb_group`.`price` AS `price`,
(
    `ORDERS`.`Ordered` * `qb_group`.`price`
) AS `Total`,

IF (
(
    `wp_postmeta`.`meta_value` = NULL
),
`ORDERS`.`Shipped`,
`ORDERS`.`Ordered`
) AS `Shipped`,
 `qb_group`.`group_name` AS `group_name`,
 `wp_postmeta`.`meta_value` AS `ship_date`,
 `qb_suborder_shipments`.`suborder` AS `suborder`,
 `qb_suborder_shipments`.`sub_qty` AS `sub_qty`,
 `qb_suborder_shipments`.`sub_shipdate` AS `sub_shipdate`
FROM
(
    (
        (
            `ORDERS`
            JOIN `qb_group` ON (
                (
                    `ORDERS`.`Item ID` = `qb_group`.`order_item_id`
                )
            )
        )
        LEFT JOIN `wp_postmeta` ON (
            (
                `ORDERS`.`Order ID` = `wp_postmeta`.`post_id`
            )
        )
    )
    LEFT JOIN `qb_suborder_shipments` ON (
        (
            `ORDERS`.`Order ID` = `qb_suborder_shipments`.`order_id`
        )
    )
)
WHERE
(
    `wp_postmeta`.`meta_key` = _utf8 '_completed_date'
)

Answer 1

首先，我会重写您的查询，以便它清晰可读：

   SELECT o.`Order ID`, /* Avoid spaces in column names */
          o.`Item ID`,  /* Avoid aliasing columns to the same thing */
          qbg.product,
          qbg.qb_product,
          qbg.description,
          o.Ordered, /* Avoid capitals in column names */
          qbg.price,
          o.Ordered*qbg.price Total,
          IF(wppm.meta_value IS NULL, o.Shipped, o.Ordered) Shipped,
          qbg.group_name, /* x = NULL will always return false use IS NULL */
          wppm.metavalue ship_date,
          qbsos.suborder,
          qbsos.sub_qty,
          qbsos.sub_shipdate
     FROM ORDERS o /* Alias your table names */
     JOIN qb_group qbg /* Avoid unnecessary parentheses */
       ON qbg.order_item_id=o.`Item ID`
     JOIN wp_postmeta wppm 
       ON wppm.post_id = o.`Order ID`
      AND wppm.meta_key = _utf8 '_completed_date'
LEFT JOIN qb_suborder_shipments qbsos 
       ON qbsos.order_id = o.`Order ID`

您的WHERE wppm.meta_key = _utf8 '_completed_date'拒绝了您的LEFT JOIN，因此我将其更改为JOIN并将其添加到ON条款中。

你是对的，这应该相当快..运行EXPLAIN ...找到瓶颈。如果您想进一步输入，请在此处发布。

查询执行时间过长

1 个答案: