Question

我创建了一个查询，它以aprox 2秒执行前100名。如果我创建这个确切查询的存储过程，则需要12-13秒才能运行。

为什么会这样？

元素表计数= 2309015（指定用户ID = 326969）
匹配表计数= 1290（指定用户ID = 498）
sites table count = 71（指定用户ID = 9）

码

 with search (elementid, siteid, title, description, site, link, addeddate)
 as
 (
     select top(@top) 
         elementid,
         elements.siteid, title, elements.description,
         site =
             case sites.description
                 when '' then sites.name
                 when null then sites.name
                 else sites.name + ' (' + sites.description + ')'
             end, 
        elements.link,
        elements.addeddate 
    from elements
        left join sites on elements.siteid = sites.siteid
    where title like @search and sites.userid = @userid
    order by addeddate desc
)
select search.*, isnull(matches.elementid,0) as ismatch 
from search
    left join matches on matches.elementid = search.elementid

Answer 1

当您创建SP时，它会被编译和存储，当SP具有参数时，您通过该参数过滤结果，优化器不知道您将在执行时传递哪个值，然后将其视为33％选择并由此制定计划。执行查询时，会提供值，优化程序会根据此值创建执行计划。我确定，计划是不同的。

Answer 2

没有代码，我只能猜测。编写示例查询时，首先有一个常量where子句，第二个是缓存。存储过程无法根据where子句中的常量缓存或优化查询计划。

Answer 3

我可以建议两种方法尝试

首先，写下你的sp：

create procedure sp_search
(
    @top int,
    @search nvarchar(max),
    @userid int
)
as
begin
    declare @p_top int, @p_search nvarchar(max), @p_userid int

    select @p_top = @top, @p_search = @search, @p_userid = @userid

    with search (elementid, siteid, title, description, site, link, addeddate)
    as
    (
        select top(@p_top) 
            elementid,
            elements.siteid, title, elements.description,
            site =
             case sites.description
                 when '' then sites.name
                 when null then sites.name
                 else sites.name + ' (' + sites.description + ')'
             end, 
            elements.link,
            elements.addeddate 
        from elements
            left join sites on elements.siteid = sites.siteid
        where title like @p_search and sites.userid = @p_userid
        order by addeddate desc
    )
    select search.*, isnull(matches.elementid,0) as ismatch 
    from search
        left join matches on matches.elementid = search.elementid
end

第二个，使用内联表函数

create function sf_search
(
    @top int,
    @search nvarchar(max),
    @userid int
)
returns table
as
return
(
    with search (elementid, siteid, title, description, site, link, addeddate)
    as
    (
        select top(@top) 
            elementid,
            elements.siteid, title, elements.description,
            site =
             case sites.description
                 when '' then sites.name
                 when null then sites.name
                 else sites.name + ' (' + sites.description + ')'
             end, 
            elements.link,
            elements.addeddate 
        from elements
            left join sites on elements.siteid = sites.siteid
        where title like @search and sites.userid = @userid
        order by addeddate desc
    )
    select search.*, isnull(matches.elementid,0) as ismatch 
    from search
        left join matches on matches.elementid = search.elementid
)

Answer 4

有一个类似的问题here

问题是存储过程声明SET ANSI_NULLS OFF

查询比存储过程慢得多？

4 个答案: