在数据的使用过程中，由于索引page碎片过多，带来一些不利的性能问题，我们有时候需要对数据库中的索引进行重组或者重建工作。通常这个阈值为30%，大于30%我们建议进行索引重建，小于则进行重组操作。以下脚本可以针对固定的数据库进行自动的索引重建和重组工作：
set nocount on --使用游标重新组织指定库中的索引,消除索引碎片 --R_T层游标取出当前数据库所有表
declare R_T cursor
forselectnamefrom sys.tables
declare @T varchar(50)
open r_t
fetch next from r_t into @t while@@fetch_status=0
begin
--R_index游标判断指定表索引碎片情况并优化
declare R_Index cursor
forselectt.name,i.name,s.avg_fragmentation_in_percentfrom sys.tables t
join sys.indexes i on i.object_id=t.object_id
join sys.dm_db_index_physical_stats(db_id(),object_id(@T),null,null,'limited') s
on s.object_id=i.object_id and s.index_id=i.index_id
declare @TName varchar(50),@IName varchar(50),@avgint,@str varchar(500)
open r_index
fetch next from r_index into @TName,@Iname,@avg
while@@fetch_status=0
begin
if@avg>=30--如果碎片大于30,重建索引
begin
set@str='alter index '+rtrim(@Iname)+' on dbo.'+quotename(rtrim(@tname))+' rebuild'
end
else--如果碎片小于30,重新组织索引
begin
set@STR='alter index '+rtrim(@Iname)+' on dbo.'+quotename(rtrim(@tname))+' reorganize'
end
print @str
exec (@str) --执行
fetch next from r_index into @TName,@Iname,@avg
end
--结束r_index游标
close r_index
deallocate r_index
fetch next from r_t into @t
end
--结束R_T游标
close r_t
deallocate r_t
setnocount off
上述代码可以针对指定的数据库，进行索引的重组重建的工作，我们也可以针对数据库中的所有数据库进行相应的工作，以下代码来源于
DECLARE @Database VARCHAR(255)
DECLARE @Table VARCHAR(255)
DECLARE @cmd NVARCHAR(500)
DECLARE @fillfactor INT
SET @fillfactor =90
DECLARE DatabaseCursor CURSOR FOR
SELECT name FROM master.dbo.sysdatabases
WHERE name NOT IN ('master','msdb','tempdb','model','distribution')
ORDER BY 1
OPEN DatabaseCursor
FETCH NEXT FROM DatabaseCursor INTO @Database
WHILE @@FETCH_STATUS =0
BEGIN
SET @cmd ='DECLARE TableCursor CURSOR FOR SELECT ''['' + table_catalog + ''].['' + table_schema + ''].['' + table_name +'']''astableName FROM [' + @Database + '].INFORMATION_SCHEMA.TABLES
WHERE table_type =''BASE TABLE'''-- create table cursor
EXEC (@cmd)
OPEN TableCursor
FETCH NEXT FROM TableCursor INTO @Table
WHILE @@FETCH_STATUS =0
BEGIN
IF (@@MICROSOFTVERSION / POWER(2,24) >=9)
BEGIN
-- SQL2005 or higher command
SET @cmd ='ALTER INDEX ALL ON '+ @Table +' REBUILD WITH (FILLFACTOR = '+ CONVERT(VARCHAR(3),@fillfactor) +')'
EXEC (@cmd)
END
ELSE
BEGIN
-- SQL2000 command
DBCC DBREINDEX(@Table,'',@fillfactor)
END
FETCH NEXT FROM TableCursor INTO @Table
END
CLOSE TableCursor
DEALLOCATE TableCursor
FETCH NEXT FROM DatabaseCursor INTO @Database
END
CLOSE DatabaseCursor
DEALLOCATE DatabaseCursor
大家可以根据代码灵活的选择重建和重组索引，并设置不同的阈值。微软件推荐索引的填充因子为90.