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	SQL SERVER 2008 R2如何重建索引
		
		SQL SERVER 2008 R2如何重建索引
项目升级数据库由SQL2000升级到2008R2,今天对数据库表进行碎片扫描,发现有些表碎片较大,于是决定重建索引,MSDN联机帮助是最好的老师,将相关脚本摘录备后查。
参考sys.dm_db_index_physical_stats
检查索引碎片情况
?
- SELECT
 - OBJECT_NAME(object_id) as objectname,
 - object_id AS objectid,
 - index_id AS indexid,
 - partition_number AS partitionnum,
 - avg_fragmentation_in_percent AS fra
 - FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, 'LIMITED')
 - WHERE avg_fragmentation_in_percent > 10.0 AND index_id > 0;
 - 使用脚本中的 sys.dm_db_index_physical_stats 重新生成或重新组织索引 (来源于联机帮助)
 - SET NOCOUNT ON;
 - DECLARE @objectid int;
 - DECLARE @indexid int;
 - DECLARE @partitioncount bigint;
 - DECLARE @schemaname nvarchar(130);
 - DECLARE @objectname nvarchar(130);
 - DECLARE @indexname nvarchar(130);
 - DECLARE @partitionnum bigint;
 - DECLARE @partitions bigint;
 - DECLARE @frag float;
 - DECLARE @command nvarchar(4000);
 - -- Conditionally select tables and indexes from the sys.dm_db_index_physical_stats function
 - -- and convert object and index IDs to names.
 - SELECT
 - object_id AS objectid,
 - index_id AS indexid,
 - partition_number AS partitionnum,
 - avg_fragmentation_in_percent AS frag
 - INTO #work_to_do
 - FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, 'LIMITED')
 - WHERE avg_fragmentation_in_percent > 10.0 AND index_id > 0;
 - -- Declare the cursor for the list of partitions to be processed.
 - DECLARE partitions CURSOR FOR SELECT * FROM #work_to_do;
 - -- Open the cursor.
 - OPEN partitions;
 - -- Loop through the partitions.
 - WHILE (1=1)
 - BEGIN;
 - FETCH NEXT
 - FROM partitions
 - INTO @objectid, @indexid, @partitionnum, @frag;
 - IF @@FETCH_STATUS < 0 BREAK;
 - SELECT @objectname = QUOTENAME(o.name), @schemaname = QUOTENAME(s.name)
 - FROM sys.objects AS o
 - JOIN sys.schemas as s ON s.schema_id = o.schema_id
 - WHERE o.object_id = @objectid;
 - SELECT @indexname = QUOTENAME(name)
 - FROM sys.indexes
 - WHERE object_id = @objectid AND index_id = @indexid;
 - SELECT @partitioncount = count (*)
 - FROM sys.partitions
 - WHERE object_id = @objectid AND index_id = @indexid;
 - -- 30 is an arbitrary decision point at which to switch between reorganizing and rebuilding.
 - IF @frag < 30.0
 - SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REORGANIZE';
 - IF @frag >= 30.0
 - SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REBUILD';
 - IF @partitioncount > 1
 - SET @command = @command + N' PARTITION=' + CAST(@partitionnum AS nvarchar(10));
 - EXEC (@command);
 - PRINT N'Executed: ' + @command;
 - END;
 - -- Close and deallocate the cursor.
 - CLOSE partitions;
 - DEALLOCATE partitions;
 - -- Drop the temporary table.
 - DROP TABLE #work_to_do;
 - GO
 
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