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 for select name from 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 for select t.name,i.name,s.avg_fragmentation_in_percent from 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),@avg int,@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 set nocount 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 + '']'' as tableName 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 -- SQL 2005 or higher command SET @cmd = 'ALTER INDEX ALL ON ' + @Table + ' REBUILD WITH (FILLFACTOR = ' + CONVERT(VARCHAR(3),@fillfactor) + ')' EXEC (@cmd) END ELSE BEGIN -- SQL 2000 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.