sql-server - 如何最好地执行这个执行计划

Question

我们的仓库管理包在存储过程方面存在瓶颈(众多瓶颈之一)，主要的速度减慢是由于生成此执行计划的查询造成的。

https://www.brentozar.com/pastetheplan/?id=HkNg65elP

存储过程可能需要 3 到 10 秒才能运行，这在其运行的业务流程上下文中相当慢。

一些附加信息:是的，有一个表正在进行全表扫描，但该表很窄，只有 76 行。该查询执行一些左连接和一些排序，这是产生正确的顶部结果所需的。总的来说，它有点像“Rube Goldberg”类型的查询，可能可以简化，但我的目标是看看是否可以帮助建立一些索引(我已经完成了，它有一点帮助)，甚至是一些如果需要，对查询进行小调整。

最后，我需要根据计划知道接下来要关注的地方。

这是查询:

SELECT TOP 1 loc.location_id, loc.wh_id
FROM t_item_uom itu WITH (NOLOCK)
    INNER JOIN t_class_loca clc WITH (NOLOCK)
        ON itu.wh_id = clc.wh_id
        AND ISNULL(dbo.usf_get_item_class_dia_ovrd ('13098271', '895', itu.uom, NULL), itu.class_id) = clc.class_id  

    INNER JOIN t_location loc WITH (NOLOCK)
        ON clc.wh_id = loc.wh_id
        AND clc.location_id = loc.location_id

    INNER JOIN t_pick_area pka WITH (NOLOCK)
        ON pka.pick_area = loc.pick_area
        AND pka.wh_id = loc.wh_id
        AND (pka.pick_area <> N'LABEL' OR (pka.pick_area = N'LABEL' AND 0 IS NULL AND 0 IS NULL) )
        AND (pka.pick_area_type = 'R' OR (pka.pick_area_type = 'V' and 0 IS NULL)  )
                                         
   INNER JOIN t_zone_loca zlc WITH (NOLOCK)
        ON loc.wh_id = zlc.wh_id
        AND loc.location_id = zlc.location_id
          INNER JOIN (
                  SELECT loc.wh_id, loc.pnd_location_id --, loc.location_id
                  FROM t_location loc with (nolock)
                  inner join t_class_loca clc WITH (NOLOCK)
                         on clc.location_id = loc.location_id
                         and clc.wh_id = loc.wh_id
                         and clc.class_id = 'APPAREL'
                  LEFT JOIN t_stored_item sto with (nolock)
                         ON sto.put_away_location = loc.location_id
                         AND sto.wh_id = loc.wh_id      --BTH 20160907 missing wh_id
                         AND sto.put_away_location IS NOT NULL
                         AND sto.type = 0
                  WHERE loc.type in ('I','M')
                  AND loc.pnd_location_id IS NOT NULL --BTH 20160907 - remove from having clause, add here
                  GROUP BY loc.wh_id, loc.pnd_location_id, loc.c3
                  HAVING ((COUNT(sto.hu_id) < 100 
                            and loc.pnd_location_id IS NOT NULL  --BTH 201600907
                            and c3 is null)
                  OR (COUNT(sto.hu_id) < 500 --and loc.pnd_location_id IS NOT NULL   --BTH 201600907
                  and c3 = 'BULK'))
                        ) as pnd
                  ON pnd.wh_id = loc.wh_id
                  AND pnd.pnd_location_id = loc.pnd_location_id

          LEFT OUTER JOIN t_put_rules_empty_and_unalloc_locs_by_pnd tpr WITH (NOLOCK)
                  ON tpr.pnd_location_id = loc.pnd_location_id
                  AND tpr.class_id = itu.class_id
                  AND tpr.wh_id = loc.wh_id

          LEFT OUTER JOIN t_work_q q WITH(NOLOCK)
                  ON q.location_id = loc.location_id
                  AND q.wh_id = loc.wh_id 
                  AND q.work_type = '08'
                  AND q.work_status = 'U'

WHERE loc.status = 'E'
    AND ISNULL(q.work_q_id, 0) = 0 
    AND ( loc.c3 is null or loc.c3 not in ('R','H','S'))
    AND ( 
                  (
                  loc.type = 'M'
                         AND ( (SELECT TOP 1 max_sku_count
                                FROM t_zone zone2 (NOLOCK)
                                WHERE zone2.wh_id = loc.wh_id
                                 AND loc.zone = zone2.zone) >
                                    (SELECT COUNT(sto2.item_number)
                                     FROM t_stored_item sto2 (NOLOCK)
                                     WHERE loc.wh_id = sto2.wh_id
                                     AND loc.location_id = sto2.location_id
                                     )
                                OR '13098271' IN (SELECT sto2.item_number
                                                    FROM t_stored_item sto2 (NOLOCK)
                                                   WHERE loc.wh_id = sto2.wh_id
                                                     AND loc.location_id = sto2.location_id
                                                  )
                              )
                    )
        OR (loc.type = 'I' AND itu.unit_volume = 0 AND itu.nested_volume = 0)
        OR (loc.type = 'I' AND loc.capacity_volume = 0)
        OR (loc.type = 'I' AND loc.capacity_volume >= 0 +
            (CASE 
                 WHEN 0 = 0 THEN 0
                 ELSE 0
             END * (1 - 1)
             )
            )
          )

   --Ensure that only one item is designated to the location
                  AND (loc.type = 'M'
                         OR (loc.type = 'I' AND NOT EXISTS (SELECT 1 
                                                        FROM t_stored_item sto2 WITH (NOLOCK)  -- Sum the item in the location to determine volume
                                                      WHERE sto2.wh_id = loc.wh_id
                                                         AND sto2.put_away_location = loc.location_id)))
    AND itu.wh_id = '895'
    AND itu.item_number = '13098271'
    AND clc.class_id = 'APPAREL'
    AND zlc.zone = 'ALL'
ORDER BY 
          tpr.percent_empty_and_unalloc DESC,
          loc.type, 
          loc.user_count, 
          loc.picking_flow, 
          loc.location_id

Answer 1

基于对您的执行计划的一些快速浏览。根据成本，问题 1 和问题 3 将为您带来最佳的投资返回率。

第一期:Key Lookup

在您的索引 IDX_wh_id_status_pnd_location_id 上，您的索引的 INCLUDE 部分缺少列 zone。

第二期:Implicit Conversions

简而言之:您正在比较不同类型的列。确保比较相同类型的列。如果这些是外键列，则两个表中的类型应该完全相同。如果它们是参数，请更改类型或转换/隐藏它们。

第三期:聚合

您对 [t_stored_item].[sto].put_away_location 进行了聚合(最大值、计数、平均值等)，行估计值为 129108。 尝试创建一个 indexed view对于这部分查询，在索引 View 中进行聚合。请改用索引 View 。 More info

估计与实际情况相差甚远，您可以尝试重建统计数据，但这可能没有帮助。为什么？ Read this

第四期:用户定义函数

您有一个带有 usf_get_item_class_dia_ovrd 的 INNER JOIN 是否可以内联编写用户定义函数的逻辑？当我们内联执行时，代码通常会得到优化，现在标量函数是逐行执行而不是基于集合执行。

第五个问题:持续扫描 - 实际行数 0

这可能不是一个大问题，但当表达式相互抵消时，通常会发生这种情况。虚拟示例:1 = 0 将始终计算为 0 行，因此 SQL Server 将其替换为空常量扫描。 在复杂的查询中，您可能无法立即找到这些内容。这不会对性能产生太大影响，但当您从查询中删除这些计划时，您可能会获得更好的执行计划。

有兴趣观看this video更好地理解查询优化器。 (有点旧，但仍然相关)

奖励:参数嗅探

您提到这是一个存储过程。存储过程通常会出现 parameters sniffing 的问题。 .