【发布时间】：2020-11-08 06:13:48
【问题描述】：
我们的仓库管理包的存储过程存在瓶颈（众多瓶颈之一），主要的减速是由于产生此执行计划的查询。
https://www.brentozar.com/pastetheplan/?id=HkNg65elP
存储过程可能需要 3 到 10 秒的时间来运行，这在它运行的业务流程的上下文中是相当慢的。
一些附加信息：是的，有一个表正在执行全表扫描，但该表很窄，只有 76 行。该查询进行了一些左连接和一些排序，这是产生正确的顶部结果所需的。总体而言，它有点像“Rube Goldberg”类型的查询，可能会被简化，但我的目标是看看是否有可能帮助一些索引（我已经完成并且帮助了一点）甚至一些如果需要，对查询进行小幅调整。
最后，我需要根据计划知道下一步的重点。
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
【问题讨论】：
-
我没有详细查看您的计划，但如果您想了解有关“如何处理”计划的一般提示：最好首先查看“估计的行数”与“实际行数”有很大不同。通常要大得多。在计划查看器（如 SSMS）中，您可以通过将鼠标悬停在箭头上来查看。专注于“粗”箭头。作为这种影响的一个例子，如果估计值很小但实际值很大，SQL 可能会选择一个嵌套循环，其中哈希匹配会更好。您有几个地方的估计值 100000。
-
我认为没有快速解决方法，但您可以尝试在查询中添加
OPTION (RECOMPILE)提示。许多 OR 条件难以优化。 -
我只是查看了实际的查询（而不是计划），是的，Dan 是正确的。有许多构造，例如
or (pka.pick_area_type = @7 and @8 is null)。这是一种“可选参数”查询。这与我之前的评论一致，SQL 对计划的叶子产生了错误的估计。就像ix_location.idx_wh_id_status...上的索引查找一样。用于生成初始执行计划的参数值适用于这些值，但在参数更改时则不然。强制 SQL 为使用option(recompile)传递的实际值生成一个新计划。
标签： sql-server sql-execution-plan