我有一个脚本来重建/重新组织索引,如下所示在Azure SQL服务器中。问题是它会导致应用程序挂起,因为所有数据库会话都将从此脚本中获取。它在游标内调用重建sql语句,所以我预计它会一个接一个地重建索引。但似乎所有索引重建都将并行运行,否则没有理由数据库开始挂起并且在此过程中无法建立连接。如果要重建的索引很少,则没问题。当有大约 60 个索引要重建时,问题就开始了。有没有办法强制一个接一个地构建索引?(顺序,而不是并行(。
CREATE PROCEDURE [dbo].[RebuildIndexes]
AS
BEGIN
SET NOCOUNT ON;
DECLARE @objectid int;
DECLARE @indexid int;
DECLARE @partitioncount bigint;
DECLARE @schemaname nvarchar(130);
DECLARE @objectname nvarchar(130);
DECLARE @indexname nvarchar(250);
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 #indexes_to_build
FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, 'LIMITED')
WHERE avg_fragmentation_in_percent > 10.0 AND index_id > 0 and page_count > 200
ORDER BY avg_fragmentation_in_percent DESC;
-- Declare the cursor for the list of partitions to be processed.
DECLARE partitions CURSOR FOR SELECT * FROM #indexes_to_build;
-- 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 WITH (ONLINE = ON)';
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 #indexes_to_build;
COMMIT;
END;
有没有办法强制一个接一个地构建索引?
TSQL 始终按顺序执行。 您的 ALTER INDEX 命令也不例外。
最后COMMIT
是问题所在。 如前所述,该过程只会在IMPLICIT_TRANSACTIONS的情况下运行。 在循环后使用 COMMIT,您可以在重建目标索引时在目标索引上累积独占锁 (Sch-M(。 当您处理大量索引时,您将阻止越来越多的其他会话。
你不应该那样做。 相反,不要在每次重新生成索引后使用 IMPLICIT_TRANSACTIONS 或 COMMIT 。 例如:
IF @partitioncount > 1
SET @command = @command + N' PARTITION=' + CAST(@partitionnum AS nvarchar(10));
EXEC (@command);
PRINT N'Executed: ' + @command;
COMMIT;
我的建议是使用Ola Hallemgren的存储过程名称Index Optimize,您可以从这里下载。每个人都使用他的脚本来完成索引维护任务。
可以运行如下所示的存储过程:
EXECUTE dbo.IndexOptimize
@Databases = 'mydbnamehere',
@FragmentationLow = NULL,
@FragmentationMedium = 'INDEX_REORGANIZE,INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE',
@FragmentationHigh = 'INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE',
@FragmentationLevel1 = 5,
@FragmentationLevel2 = 30,
@UpdateStatistics = 'ALL',
@OnlyModifiedStatistics = 'Y'
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