SQL Server 索引碎片整理

索引碎片整理的四種方法：

1）洗掉索引并重建

2）使用 DROP_EXISTING 陳述句重建索引

3）使用 ALTER INDEX REBUILD 陳述句重建索引

4）使用 ALTER INDEX REORGANIZE 重新組織索引

--1.查看碎片
SELECT  DB_NAME() AS DatbaseName ,
        SCHEMA_NAME(o.Schema_ID) AS SchemaName ,
        OBJECT_NAME(s.[object_id]) AS TableName ,
        i.name AS IndexName ,
        ROUND(s.avg_fragmentation_in_percent, 2) AS [Fragmentation %] ,
        CASE WHEN avg_fragmentation_in_percent > 30 THEN '嚴重碎片，索引需要重建'
             WHEN avg_fragmentation_in_percent >= 5
                  AND avg_fragmentation_in_percent < 30 THEN '輕度碎片，索引需要重新組織'
             ELSE '正常狀態'
        END 提示
FROM    sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL, NULL, NULL) s
        INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id] AND s.index_id = i.index_id
        INNER JOIN sys.objects o ON i.object_id = O.object_id
ORDER BY [Fragmentation %] DESC  
 
--2.整理碎片（建議在空閑時間運行，尤其不要在生產環境運行）
SET NOCOUNT ON
DECLARE @Objectid INT ,
    @Indexid INT ,
    @schemaname VARCHAR(100) ,
    @tablename VARCHAR(300) ,
    @ixname VARCHAR(500) ,
    @avg_fip FLOAT ,
    @command VARCHAR(4000)
DECLARE IX_Cursor CURSOR
FOR
    SELECT  A.object_id ,
            A.index_id ,
            QUOTENAME(SS.NAME) AS schemaname ,
            QUOTENAME(OBJECT_NAME(B.object_id, B.database_id)) AS tablename ,
            QUOTENAME(A.name) AS ixname ,
            B.avg_fragmentation_in_percent AS avg_fip
    FROM    sys.indexes A
            INNER JOIN sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL,
                                                      NULL, 'LIMITED') AS B ON A.object_id = B.object_id
                                                              AND A.index_id = B.index_id
            INNER JOIN SYS.OBJECTS OS ON A.object_id = OS.object_id
            INNER JOIN sys.schemas SS ON OS.schema_id = SS.schema_id
    WHERE   B.avg_fragmentation_in_percent > 10
            AND B.page_count > 20
            AND A.index_id > 0
            AND A.IS_DISABLED <> 1
            --AND OS.name='book'
ORDER BY    avg_fip DESC ,
            tablename ,
            ixname
OPEN IX_Cursor
FETCH NEXT FROM IX_Cursor INTO @Objectid, @Indexid, @schemaname, @tablename,
    @ixname, @avg_fip
WHILE @@FETCH_STATUS = 0 
    BEGIN 
        --碎片率>5%或<=30%，索引重組
        IF @avg_fip < 30.0 
            SET @command = N'ALTER INDEX ' + @ixname + N' ON ' + @schemaname
                + N'.' + @tablename + N' REORGANIZE ';
                
        --碎片率>=30%，索引重建
        IF @avg_fip >= 30.0
            AND @Indexid = 1 
            BEGIN
                IF EXISTS ( SELECT  *
                            FROM    SYS.columns
                            WHERE   OBJECT_ID = @Objectid
                                    AND max_length IN ( -1, 16 ) ) 
                    SET @command = N'ALTER INDEX ' + @ixname + N' ON '
                        + @schemaname + N'.' + @tablename + N' REBUILD ';
                ELSE 
                    SET @command = N'ALTER INDEX ' + @ixname + N' ON '
                        + @schemaname + N'.' + @tablename + N' REBUILD '
                        + N' WITH (ONLINE = ON)';
            END
        IF @avg_fip >= 30.0
            AND @Indexid > 1 
            BEGIN 
                IF EXISTS ( SELECT  *
                            FROM    SYS.index_columns IC
                                    INNER JOIN SYS.columns CS ON CS.OBJECT_ID = IC.OBJECT_ID
                                                              AND CS.column_id = IC.column_id
                            WHERE   IC.OBJECT_ID = @Objectid
                                    AND IC.index_id = @Indexid
                                    AND CS.max_length IN ( -1, 16 ) ) 
                    SET @command = N'ALTER INDEX ' + @ixname + N' ON '
                        + @schemaname + N'.' + @tablename + N' REBUILD ';
                ELSE 
                    SET @command = N'ALTER INDEX ' + @ixname + N' ON '
                        + @schemaname + N'.' + @tablename + N' REBUILD '
                        + N' WITH (ONLINE = ON)';
            END
        --列印命令，單獨執行
        PRINT @command
        
        --直接執行命令
        --EXEC(@command)
 
        FETCH NEXT FROM IX_Cursor INTO @Objectid, @Indexid, @schemaname,@tablename, @ixname, @avg_fip
    END 
CLOSE IX_Cursor
DEALLOCATE IX_Cursor 

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