文章摘要
文章主要介绍了一种使用SQL脚本从`sys.dm_db_index_physical_stats`函数中提取和处理索引信息的方法。通过从存储过程`sys.dm_db_index_physical_stats`中获取索引的元数据，包括索引ID、对象ID、分区号和平均碎片化百分比，并将其存储到临时表`#work_to_do`中。随后，代码通过循环处理每个索引，判断其碎片化程度，决定是重新组织还是重建索引。这种方法可以帮助数据库管理员动态优化索引性能，提升数据库运行效率。
1.SELECT
2.OBJECT_NAME(object_id) as objectname,
3.object_id AS objectid,
4.index_id AS indexid,
5.partition_number AS partitionnum,
6.avg_fragmentation_in_percent AS fra
7.FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, ‘LIMITED’)
8.WHERE avg_fragmentation_in_percent > 10.0 AND index_id > 0;
9.
10.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）
11.
12.SET NOCOUNT ON;
13.DECLARE @objectid int;
14.DECLARE @indexid int;
15.DECLARE @partitioncount bigint;
16.DECLARE @schemaname nvarchar(130);
17.DECLARE @objectname nvarchar(130);
18.DECLARE @indexname nvarchar(130);
19.DECLARE @partitionnum bigint;
20.DECLARE @partitions bigint;
21.DECLARE @frag float;
22.DECLARE @command nvarchar(4000);
23.– Conditionally select tables and indexes from the sys.dm_db_index_physical_stats function
24.– and convert object and index IDs to names.
25.SELECT
26.object_id AS objectid,
27.index_id AS indexid,
28.partition_number AS partitionnum,
29.avg_fragmentation_in_percent AS frag
30.INTO #work_to_do
31.FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, ‘LIMITED’)
32.WHERE avg_fragmentation_in_percent > 10.0 AND index_id > 0;
33.– Declare the cursor for the list of partitions to be processed.
34.DECLARE partitions CURSOR FOR SELECT * FROM #work_to_do;
35.– Open the cursor.
36.OPEN partitions;
37.– Loop through the partitions.
38.WHILE (1=1)
39.BEGIN;
40.FETCH NEXT
41.FROM partitions
42.INTO @objectid, @indexid, @partitionnum, @frag;
43.IF @@FETCH_STATUS < 0 BREAK;
44.SELECT @objectname=QUOTENAME(o.name), @schemaname=QUOTENAME(s.name)
45.FROM sys.objects AS o
46.JOIN sys.schemas as s ON s.schema_id=o.schema_id
47.WHERE o.object_id=@objectid;
48.SELECT @indexname=QUOTENAME(name)
49.FROM sys.indexes
50.WHERE object_id=@objectid AND index_id=@indexid;
51.SELECT @partitioncount=count (*)
52.FROM sys.partitions
53.WHERE object_id=@objectid AND index_id=@indexid;
54.– 30 is an arbitrary decision point at which to switch between reorganizing and rebuilding.
55.IF @frag < 30.0
56.SET @command=N‘ALTER INDEX ‘ + @indexname + N‘ ON ‘ + @schemaname + N‘.’ + @objectname + N‘ REORGANIZE’;
57.IF @frag >=30.0
58.SET @command=N‘ALTER INDEX ‘ + @indexname + N‘ ON ‘ + @schemaname + N‘.’ + @objectname + N‘ REBUILD’;
59.IF @partitioncount > 1
60.SET @command=@command + N‘ PARTITION=’ + CAST(@partitionnum AS nvarchar(10));
61.EXEC (@command);
62.PRINT N‘Executed: ‘ + @command;
63.END;
64.– Close and deallocate the cursor.
65.CLOSE partitions;
66.DEALLOCATE partitions;
67.– Drop the temporary table.
68.DROP TABLE #work_to_do;
69.GO