重建索引

SET NOCOUNT ON;

DECLARE @objectid int;

DECLARE @indexid int;

DECLARE @partitioncount bigint;

DECLARE @schemaname nvarchar(258);

DECLARE @objectname nvarchar(258);

DECLARE @indexname nvarchar(258);

DECLARE @partitionnum bigint;

DECLARE @partitions bigint;

DECLARE @frag float;

DECLARE @command varchar(8000);

-- ensure the temporary table does not exist

IF EXISTS (SELECT name FROM sys.objects WHERE name = 'work_to_do')

DROP TABLE work_to_do;

-- conditionally select from the function, converting object and index IDs to names.

-- 将符合所设条件的IndexID选出来，并将名称转换为友好名称

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')

-- *****************************

-- 此参数设定很重要 avg_fragmentation_in_percent > 10.0

-- *****************************

WHERE avg_fragmentation_in_percent > 10.0 AND index_id > 0;

-- Declare the cursor for the list of partitions to be processed.

-- 声明打开分区列表的游标

DECLARE partitions CURSOR FOR SELECT * FROM work_to_do;

-- Open the cursor.

-- 打开游标

OPEN partitions;

-- Loop through the partitions.

-- 循环遍历分区

FETCH NEXT

FROM partitions

INTO @objectid, @indexid, @partitionnum, @frag;

WHILE @@FETCH_STATUS = 0

BEGIN;

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

-- 设定重新生成和重新组织的边界条件

-- *****************************

-- 此参数设定很重要

-- *****************************

IF @frag < 5.0

BEGIN;

SELECT @command = 'ALTER INDEX ' + @indexname + ' ON '

+ @schemaname + '.' + @objectname + ' REORGANIZE';

IF @partitioncount > 1

SELECT @command = @command + ' PARTITION='

+ CONVERT (CHAR, @partitionnum);

EXEC (@command);

END;

IF @frag >= 5.0

BEGIN;

SELECT @command = 'ALTER INDEX ' + @indexname +' ON ' + @schemaname

+ '.' + @objectname + ' REBUILD';

IF @partitioncount > 1

SELECT @command = @command + ' PARTITION='

+ CONVERT (CHAR, @partitionnum);

EXEC (@command);

END;

PRINT 'Executed ' + @command;

FETCH NEXT FROM partitions INTO @objectid, @indexid, @partitionnum, @frag;

END;

-- Close and deallocate the cursor.

-- 关闭释放游标

CLOSE partitions;

DEALLOCATE partitions;

-- drop the temporary table

-- 删除临时表

IF EXISTS (SELECT name FROM sys.objects WHERE name = 'work_to_do')

DROP TABLE work_to_do;

GO