要求是在分页中加载 50 条记录，表“empl”的所有 65 列以最小 IO 加载。表中有 280000+ 条记录。PK 上只有一个聚集索引。
分页查询如下：
WITH result_set AS (
SELECT
ROW_NUMBER() OVER (ORDER BY e.[uon] DESC ) AS [row_number], e.*
FROM
empl e with (NOLOCK)
LEFT JOIN empl_add ea with (NOLOCK)
ON ea.ptid = e.ptid
WHERE
e.del = 0 AND e.pub = 1 AND e.sid = 2
AND e.md = 0
AND e.tid = 3
AND e.coid = 2
AND (e.cid = 102)
AND ea.ptgid IN (SELECT ptgid FROM empl_dep where psid = 1001
AND ib = 1))
SELECT
*
FROM
result_set
WHERE
[row_number] BETWEEN 0 AND 50
以下是从探查器运行上述查询后的统计信息：
CPU：1500，读取：25576，持续时间：25704
然后我将以下索引放在表 empl 上：
CREATE NONCLUSTERED INDEX [ci_empl]
ON [dbo].[empl] ([del],[md],[pub],[tid],[coid],[sid],[ptid],[cid],[uon])
GO
放入索引后 CPU 和 Reads 仍然更高。我不知道索引有什么问题或查询有什么问题？
编辑：
以下查询在放入索引后也进行了高读取。而且只有 3 列和 1 个计数。
SELECT TOP (2147483647)
ame.aid ID, ame.name name,
COUNT(empl.pid) [Count], ps.uff uff FROM ame with (NOLOCK)
JOIN pam AS pa WITH (NOLOCK) ON pa.aid = ame.aid
JOIN empl WITH (NOLOCK) ON empl.pid = pa.pid
LEFT JOIN psam AS ps
ON ps.psid = 1001
AND ps.aid = ame.aid
LEFT JOIN empl_add ea with (NOLOCK)
ON ea.ptid = empl.ptid
WHERE
empl.del = 0 AND empl.pub = 1 AND empl.sid = 2
AND empl.md = 0
AND (empl.tid = 3)
AND (empl.coid = 2)
AND (empl.cid = 102)
AND ea.ptgid IN (SELECT ptgid FROM empl_dep where psid = 1001
AND ib = 1)
AND ame.pub = 1 AND ame.del = 0
GROUP BY ame.aid, ame.name, ps.uff
ORDER BY ame.name ASC
第二次编辑：
现在我在“uon”列上放置了以下索引：
CREATE NONCLUSTERED INDEX [ci_empl_uon]
ON [dbo].[empl] (uon)
GO
但是 CPU 和读取仍然更高。
第三次编辑：
DTA 建议我对第一个查询中包含的所有列进行索引，因此我更改了建议的索引，将其转换为基本四个过滤器的过滤器索引，以使其更有效。
我在创建索引时在Include之后添加了以下行。
Where e.del = 0 AND e.pub = 1 AND e.sid = 2 AND e.md = 0 AND e.coid = 2
但是在开发和生产机器上的读取仍然很高。
第四次编辑：
现在我找到了一个提高性能的解决方案，但仍然达不到目标。关键是它不适用于ALL THE DATA。
查询如下：
WITH result_set AS (
SELECT
ROW_NUMBER() OVER (ORDER BY e.[uon] DESC ) AS [row_number], e.pID pID
FROM
empl e with (NOLOCK)
LEFT JOIN empl_add ea with (NOLOCK)
ON ea.ptid = e.ptid
WHERE
e.del = 0 AND e.pub = 1 AND e.sid = 2
AND e.md = 0
AND e.tid = 3
AND e.coid = 2
AND (e.cid = 102)
AND ea.ptgid IN (SELECT ptgid FROM empl_dep where psid = 1001
AND ib = 1))
SELECT
*
FROM
result_set join empl on result_set.pID = empl.pID
WHERE
[row_number] BETWEEN @start AND @end
并使用键列更改、包含和过滤重新创建索引：
CREATE NONCLUSTERED INDEX [ci_empl]
ON [dbo].[empl] ([ptid],[cid],[tid],[uon])
INCLUDE ([pID])
Where
[coID] = 2 and
[sID] = 2 and
[pub] = 1 and
[del] = 0 and
[md] = 0
GO
它提高了性能，但达不到目标。