SQL Server通过整理索引碎片和重建索引提高速度

--更新统计信息
EXEC sp_updatestats



---索引优化
DECLARE @tableName NVARCHAR(50) ,
    @indexName NVARCHAR(50) ,
    @fragmentPercent NVARCHAR(20) ,
    @sql NVARCHAR(200)= ''
DECLARE indexFragment_cursor CURSOR
FOR
    SELECT  o.name AS tableName ,
            ix.name AS indexName ,
            avg_fragmentation_in_percent AS fragmentPercent--,
    --dip.fragment_count,
    --dip.avg_fragment_size_in_pages
    FROM    sys.dm_db_index_physical_stats(DB_ID() ,NULL ,NULL ,NULL ,NULL) dip
            INNER JOIN sys.indexes ix ON ix.index_id = dip.index_id
                                         AND ix.object_id = dip.object_id
            INNER JOIN sys.objects o ON ix.object_id = o.object_id
    WHERE   dip.index_id > 0
            AND avg_fragmentation_in_percent > 5
    ORDER BY avg_fragmentation_in_percent DESC

--打开游标
OPEN indexFragment_cursor 
FETCH NEXT 
    FROM indexFragment_cursor 
    INTO @tableName ,@indexName ,@fragmentPercent
WHILE @@FETCH_STATUS = 0 
    BEGIN
    --print @tableName+'----'+@indexName++'----'+@fragmentPercent
        SET @sql = 'ALTER INDEX ' + QUOTENAME(@indexName) + ' on '
            + QUOTENAME(@tableName)
            + CASE WHEN @fragmentPercent <= '30' THEN ' REORGANIZE;'
                   WHEN @fragmentPercent > '30' THEN ' REBUILD;'
              END
    --print @sql
        EXEC(@sql)
    --移到下一行记录
        FETCH NEXT 
        FROM indexFragment_cursor 
        INTO @tableName ,@indexName ,@fragmentPercent
    END

--关闭，释放游标
CLOSE indexFragment_cursor
DEALLOCATE indexFragment_cursor



GO

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，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,  www.2cto.com  

    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;  www.2cto.com  

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));  www.2cto.com  

        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