我最近几次遇到完全相同的问题（使用 MS-SQL 2008）。特定的存储过程运行起来会非常慢（几分钟），但粘贴到 SSMS 中的相同 SQL 只需几秒钟。
问题基本上是存储过程使用了错误的执行计划，而粘贴的 SQL 使用了不同的（并且更好的）执行计划。
比较执行计划
要测试这个假设，请在 SSMS 中打开一个新的查询窗口并打开“包括实际执行计划”（Ctrl-M 是此操作的键盘快捷键）。
然后将存储过程的内容粘贴到窗口中，然后调用实际的存储过程。
例如：
从 ID = 10 的用户中选择名字、姓氏
EXEC dbo.spGetUserById 10
同时运行两个查询，然后比较两者的执行计划。我不得不说，在我的情况下，每个查询的“查询成本”估计根本没有帮助，并且给我指出了错误的方向。相反，请仔细查看正在使用的索引，是否正在执行扫描而不是搜索以及正在处理的行数。
计划应该有所不同，这应该有助于确定需要进一步调查的表和索引。
为了帮助解决这个问题，在一个实例中，我能够重写存储过程以避免使用索引扫描，而是依赖于索引搜索。
在另一个例子中，我发现更新为查询中使用的特定表重建索引会产生重大影响。
查找和更新索引
我已使用此 SQL 查找并重建适当的索引：
/* Originally created by Microsoft */
/* Error corrected by Pinal Dave (http://www.SQLAuthority.com) */
/* http://blog.sqlauthority.com/2008/03/04/sql-server-2005-a-simple-way-to-defragment-all-indexes-in-a-database-that-is-fragmented-above-a-declared-threshold/ */
/* Catch22: Added parameters to filter by table & view proposed changes */
-- Specify your Database Name
USE AdventureWorks
/* Parameters */
Declare @MatchingTableName nvarchar(100) = 'MyTablePrefix' -- Specify Table name (can be prefix of table name) or blank for all tables
DECLARE @ViewOnly bit = 1 -- Set to 1 to view proposed actions, set to 0 to Execute proposed actions:
-- Declare variables
SET NOCOUNT ON
DECLARE @tablename VARCHAR(128)
DECLARE @execstr VARCHAR(255)
DECLARE @objectid INT
DECLARE @indexid INT
DECLARE @frag decimal
DECLARE @maxreorg decimal
DECLARE @maxrebuild decimal
DECLARE @IdxName varchar(128)
DECLARE @ReorgOptions varchar(255)
DECLARE @RebuildOptions varchar(255)
-- Decide on the maximum fragmentation to allow for a reorganize.
-- AVAILABLE OPTIONS: http://technet.microsoft.com/en-us/library/ms188388(SQL.90).aspx
SET @maxreorg = 20.0
SET @ReorgOptions = 'LOB_COMPACTION=ON'
-- Decide on the maximum fragmentation to allow for a rebuild.
SET @maxrebuild = 30.0
-- NOTE: only specifiy FILLFACTOR=x if x is something other than zero:
SET @RebuildOptions = 'PAD_INDEX=OFF, SORT_IN_TEMPDB=ON, STATISTICS_NORECOMPUTE=OFF, ALLOW_ROW_LOCKS=ON, ALLOW_PAGE_LOCKS=ON'
-- Declare a cursor.
DECLARE tables CURSOR FOR
SELECT CAST(TABLE_SCHEMA AS VARCHAR(100))
+'.'+CAST(TABLE_NAME AS VARCHAR(100))
AS Table_Name
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
AND TABLE_NAME like @MatchingTableName + '%'
-- Create the temporary table.
if exists (select name from tempdb.dbo.sysobjects where name like '#fraglist%')
drop table #fraglist
CREATE TABLE #fraglist (
ObjectName CHAR(255),
ObjectId INT,
IndexName CHAR(255),
IndexId INT,
Lvl INT,
CountPages INT,
CountRows INT,
MinRecSize INT,
MaxRecSize INT,
AvgRecSize INT,
ForRecCount INT,
Extents INT,
ExtentSwitches INT,
AvgFreeBytes INT,
AvgPageDensity INT,
ScanDensity decimal,
BestCount INT,
ActualCount INT,
LogicalFrag decimal,
ExtentFrag decimal)
-- Open the cursor.
OPEN tables
-- Loop through all the tables in the database.
FETCH NEXT
FROM tables
INTO @tablename
WHILE @@FETCH_STATUS = 0
BEGIN
-- Do the showcontig of all indexes of the table
INSERT INTO #fraglist
EXEC ('DBCC SHOWCONTIG (''' + @tablename + ''')
WITH FAST, TABLERESULTS, ALL_INDEXES, NO_INFOMSGS')
FETCH NEXT
FROM tables
INTO @tablename
END
-- Close and deallocate the cursor.
CLOSE tables
DEALLOCATE tables
-- Declare the cursor for the list of indexes to be defragged.
DECLARE indexes CURSOR FOR
SELECT ObjectName, ObjectId, IndexId, LogicalFrag, IndexName
FROM #fraglist
WHERE ((LogicalFrag >= @maxreorg) OR (LogicalFrag >= @maxrebuild))
AND INDEXPROPERTY (ObjectId, IndexName, 'IndexDepth') > 0
-- Open the cursor.
OPEN indexes
-- Loop through the indexes.
FETCH NEXT
FROM indexes
INTO @tablename, @objectid, @indexid, @frag, @IdxName
WHILE @@FETCH_STATUS = 0
BEGIN
IF (@frag >= @maxrebuild)
BEGIN
IF (@ViewOnly=1)
BEGIN
PRINT 'WOULD be executing ALTER INDEX ' + RTRIM(@IdxName) + ' ON ' + RTRIM(@tablename) + ' REBUILD WITH ( ' + @RebuildOptions + ' ) -- Fragmentation currently ' + RTRIM(CONVERT(VARCHAR(15),@frag)) + '%'
END
ELSE
BEGIN
PRINT 'Now executing ALTER INDEX ' + RTRIM(@IdxName) + ' ON ' + RTRIM(@tablename) + ' REBUILD WITH ( ' + @RebuildOptions + ' ) -- Fragmentation currently ' + RTRIM(CONVERT(VARCHAR(15),@frag)) + '%'
SELECT @execstr = 'ALTER INDEX ' + RTRIM(@IdxName) + ' ON ' + RTRIM(@tablename) + ' REBUILD WITH ( ' + @RebuildOptions + ' )'
EXEC (@execstr)
END
END
ELSE IF (@frag >= @maxreorg)
BEGIN
IF (@ViewOnly=1)
BEGIN
PRINT 'WOULD be executing ALTER INDEX ' + RTRIM(@IdxName) + ' ON ' + RTRIM(@tablename) + ' REORGANIZE WITH ( ' + @ReorgOptions + ' ) -- Fragmentation currently ' + RTRIM(CONVERT(VARCHAR(15),@frag)) + '%'
END
ELSE
BEGIN
PRINT 'Now executing ALTER INDEX ' + RTRIM(@IdxName) + ' ON ' + RTRIM(@tablename) + ' REORGANIZE WITH ( ' + @ReorgOptions + ' ) -- Fragmentation currently ' + RTRIM(CONVERT(VARCHAR(15),@frag)) + '%'
SELECT @execstr = 'ALTER INDEX ' + RTRIM(@IdxName) + ' ON ' + RTRIM(@tablename) + ' REORGANIZE WITH ( ' + @ReorgOptions + ' )'
EXEC (@execstr)
END
END
FETCH NEXT
FROM indexes
INTO @tablename, @objectid, @indexid, @frag, @IdxName
END
-- Close and deallocate the cursor.
CLOSE indexes
DEALLOCATE indexes
-- Delete the temporary table.
DROP TABLE #fraglist