查询INFORMATION_SCHEMA时死锁(Deadlock when querying INF

2019-10-30 05:58发布

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我有一种方法，其根据在公开的元数据层的变化动态地改变我SQL2K5表结构。

例如，如果一个新的列需要添加和表没有依赖关系 - 步骤是：1.使用T-SQL对于已经在表中存在的任何索引＆主键创建脚本[下面包括这些脚本] 2.删除表3.重新创建从具有新列4.执行在步骤＃创建的脚本1 5填充使用BulkCopy表中的元层的表

上述经由.NET组件发起并在每天的基础上3个并发流运行。

我在第1步中收到死锁错误 - 当我访问INFORMATION_SCHEMA表来编写脚本索引/键。 我用在这些脚本想这应该防止任何锁定时，这些行动的3个数据流同时运行（NOLOCK）提示。 一个表只能在1个流进行处理（在创建或脚本）。

有更多的东西，我需要做的???

任何意见极大的赞赏。

[脚本] 

ALTER Procedure [dbo].[s$spScriptPrimaryKeyForTable]
@Tablename varchar(100)
AS 


-- Get all existing primary keys
DECLARE cPK CURSOR FOR
SELECT TABLE_NAME, CONSTRAINT_NAME 
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WITH(NOLOCK)
WHERE upper(TABLE_NAME)=upper(@Tablename)
ORDER BY TABLE_NAME

DECLARE @PkTable SYSNAME
DECLARE @PkName SYSNAME

-- Loop through all the primary keys
OPEN cPK
FETCH NEXT FROM cPK INTO @PkTable, @PkName
WHILE (@@FETCH_STATUS = 0)
BEGIN
DECLARE @PKSQL NVARCHAR(4000) SET @PKSQL = ''
SET @PKSQL = 'ALTER TABLE ' + @PkTable + ' ADD CONSTRAINT ' + @PkName + ' PRIMARY KEY CLUSTERED ('

-- Get all columns for the current primary key
DECLARE cPKColumn CURSOR FOR
SELECT COLUMN_NAME 
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WITH(NOLOCK)
WHERE TABLE_NAME = @PkTable AND CONSTRAINT_NAME = @PkName
ORDER BY ORDINAL_POSITION
OPEN cPKColumn

DECLARE @PkColumn SYSNAME
DECLARE @PkFirstColumn BIT SET @PkFirstColumn = 1
-- Loop through all columns and append the sql statement
FETCH NEXT FROM cPKColumn INTO @PkColumn
WHILE (@@FETCH_STATUS = 0)
BEGIN
IF (@PkFirstColumn = 1)
SET @PkFirstColumn = 0
ELSE
SET @PKSQL = @PKSQL + ', '

SET @PKSQL = @PKSQL + @PkColumn

FETCH NEXT FROM cPKColumn INTO @PkColumn
END
CLOSE cPKColumn
DEALLOCATE cPKColumn

SET @PKSQL = @PKSQL + ')'
-- Print the primary key statement
-- PRINT @PKSQL

FETCH NEXT FROM cPK INTO @PkTable, @PkName
END
CLOSE cPK
DEALLOCATE cPK


SELECT ISNULL(@PKSQL,' ')

================

ALTER Procedure [dbo].[s$spScriptIndexesForTable]
@Tablename varchar(100)

AS 

DECLARE @RetVal varchar(4000)
SET @RetVal = ''

-- Get all existing indexes, but NOT the primary keys 
DECLARE cIX CURSOR FOR 
SELECT OBJECT_NAME(SI.Object_ID), SI.Object_ID, SI.Name, SI.Index_ID 
FROM Sys.Indexes SI WITH(NOLOCK)
LEFT JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS TC WITH(NOLOCK) ON SI.Name = TC.CONSTRAINT_NAME AND OBJECT_NAME(SI.Object_ID) = TC.TABLE_NAME 
WHERE TC.CONSTRAINT_NAME IS NULL 
AND OBJECTPROPERTY(SI.Object_ID, 'IsUserTable') = 1 
AND upper(OBJECT_NAME(SI.Object_ID))=upper(@Tablename)
ORDER BY OBJECT_NAME(SI.Object_ID), SI.Index_ID 

DECLARE @IxTable SYSNAME 
DECLARE @IxTableID INT 
DECLARE @IxName SYSNAME 
DECLARE @IxID INT 

-- Loop through all indexes 
OPEN cIX 
FETCH NEXT FROM cIX INTO @IxTable, @IxTableID, @IxName, @IxID 
WHILE (@@FETCH_STATUS = 0) 
BEGIN 
DECLARE @IXSQL NVARCHAR(4000) 
--SET @PKSQL = '' 
SET @IXSQL = 'CREATE ' 

-- Check if the index is unique 
IF (INDEXPROPERTY(@IxTableID, @IxName, 'IsUnique') = 1) 
SET @IXSQL = @IXSQL + 'UNIQUE ' 
-- Check if the index is clustered 
IF (INDEXPROPERTY(@IxTableID, @IxName, 'IsClustered') = 1) 
SET @IXSQL = @IXSQL + 'CLUSTERED ' 

SET @IXSQL = @IXSQL + 'INDEX ' + @IxName + ' ON [' + @IxTable + '] (' 

-- Get all columns of the index 
DECLARE cIxColumn CURSOR FOR 
SELECT SC.Name,IC.[is_included_column],IC.is_descending_key 
FROM Sys.Index_Columns IC WITH(NOLOCK)
JOIN Sys.Columns SC WITH(NOLOCK) ON IC.Object_ID = SC.Object_ID AND IC.Column_ID = SC.Column_ID 
WHERE IC.Object_ID = @IxTableID AND Index_ID = @IxID 
ORDER BY IC.Index_Column_ID,IC.is_included_column 

DECLARE @IxColumn SYSNAME 
DECLARE @IxIncl bit 
DECLARE @Desc bit 
DECLARE @IxIsIncl bit set @IxIsIncl = 0 
DECLARE @IxFirstColumn BIT SET @IxFirstColumn = 1 

-- Loop throug all columns of the index and append them to the CREATE statement 
OPEN cIxColumn 
FETCH NEXT FROM cIxColumn INTO @IxColumn, @IxIncl, @Desc 
WHILE (@@FETCH_STATUS = 0) 
BEGIN 

IF (@IxFirstColumn = 1) 
BEGIN 
SET @IxFirstColumn = 0 
END 
ELSE 
BEGIN 
--check to see if it's an included column 
IF ((@IxIsIncl = 0) AND (@IxIncl = 1)) 
BEGIN 
SET @IxIsIncl = 1 
SET @IXSQL = @IXSQL + ') INCLUDE (' 
END 
ELSE 
BEGIN 
SET @IXSQL = @IXSQL + ', ' 
END 
END 

SET @IXSQL = @IXSQL + '[' + @IxColumn + ']' 
--check to see if it's DESC 
IF @Desc = 1 
SET @IXSQL = @IXSQL + ' DESC' 

FETCH NEXT FROM cIxColumn INTO @IxColumn, @IxIncl, @Desc 
END 
CLOSE cIxColumn 
DEALLOCATE cIxColumn 

SET @IXSQL = @IXSQL + ')' 

-- Print out the CREATE statement for the index 
--SELECT 'IXSQL: ' + @IXSQL
IF @RetVal IS NULL
SET @RetVal = ''
--SELECT 'Retval: ' + @RetVal
SET @RetVal = @RetVal + @IXSQL + ' ' 

FETCH NEXT FROM cIX INTO @IxTable, @IxTableID, @IxName, @IxID 
END 

CLOSE cIX 
DEALLOCATE cIX 

SELECT ISNULL(@RetVal,' ')

Answer 1:

  1. INFORMATION_SCHEMA的意见是 - 观点。 不能更新它们，所以它们是不会对身体造成死锁。 如果你想确定实际源（我假设有话跟你涂改，或其他代码光标内，你没有显示，或其他代码你在组合调用与调用这些程序 - 因为对选择意见，然后选择变量不能是原因），我建议您阅读有关解释死锁盖尔肖的博客文章 。

  2. 尽管（1）我还是建议使用比INFORMATION_SCHEMA更现代化的目录视图。 相同的信息可以从，例如，sys.key_constraints导出。

  3. 您使用的是默认光标选项; 而你嵌套游标。 如果你最终还是使用光标，你应该使用更少的资源密集型光标的习惯得到（如本地静态FORWARD_ONLY READ_ONLY）。

  4. 你实际上并不需要使用游标来做到这一点。 下面是我会重新写的PK表脚本： 

     CREATE PROCEDURE dbo.ScriptPKForTable @TableName SYSNAME AS BEGIN SET NOCOUNT ON; DECLARE @pkName SYSNAME, @clustered BIT, @object_id INT, @sql NVARCHAR(MAX); SELECT @object_id = OBJECT_ID(UPPER(@TableName)); SELECT @pkName = kc.name, @clustered = CASE i.[type] WHEN 1 THEN 1 ELSE 0 END FROM sys.key_constraints AS kc INNER JOIN sys.indexes AS i ON kc.parent_object_id = i.[object_id] AND kc.unique_index_id = i.index_id WHERE kc.parent_object_id = @object_id AND kc.[type] = 'pk'; SET @sql = N'ALTER TABLE ' + QUOTENAME(@TableName) + ' ADD CONSTRAINT ' + @pkName + ' PRIMARY KEY ' + CASE @clustered WHEN 1 THEN 'CLUSTERED' ELSE '' END + ' ('; SELECT @sql = @sql + c.name + ',' FROM sys.index_columns AS ic INNER JOIN sys.indexes AS i ON ic.index_id = i.index_id AND ic.[object_id] = i.[object_id] INNER JOIN sys.key_constraints AS kc ON i.[object_id] = kc.[parent_object_id] AND kc.unique_index_id = i.index_id INNER JOIN sys.columns AS c ON i.[object_id] = c.[object_id] AND ic.column_id = c.column_id WHERE kc.[type] = 'PK' AND kc.parent_object_id = @object_id ORDER BY key_ordinal; SET @sql = LEFT(@sql, LEN(@sql) - 1) + ');'; SELECT COALESCE(@sql, ' '); END GO

至于索引创建脚本，我认为这是一个更好的方式来做到这一点（没有明确光标再次，而不是回避光标是目标，但代码将是大量的清洁剂）。 首先，你需要一个函数从索引建立的任一按键或包括列： 

CREATE FUNCTION dbo.BuildIndexColumns
(
    @object_id        INT,
    @index_id         INT,
    @included_columns BIT
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
  DECLARE @s NVARCHAR(MAX);

  SELECT @s = N'';

  SELECT @s = @s + c.name + CASE ic.is_descending_key
    WHEN 1 THEN ' DESC' ELSE '' END + ',' 
    FROM sys.index_columns AS ic
    INNER JOIN sys.columns AS c
    ON ic.[object_id] = c.[object_id]
    AND ic.column_id = c.column_id
    WHERE c.[object_id] = @object_id
    AND ic.[object_id] = @object_id
    AND ic.index_id = @index_id
    AND ic.is_included_column = @included_columns
    ORDER BY ic.key_ordinal;

  IF @s > N''
    SET @s = LEFT(@s, LEN(@s)-1);

  RETURN (NULLIF(@s, N''));
END
GO

有了这一功能，ScriptIndexes过程是很容易的： 

CREATE PROCEDURE dbo.ScriptIndexesForTable
    @TableName SYSNAME
AS
BEGIN
  SET NOCOUNT ON;

  DECLARE
      @sql       NVARCHAR(MAX),
      @object_id INT;

  SELECT @sql = N'', @object_id = OBJECT_ID(UPPER(@TableName));

  SELECT @sql = @sql + 'CREATE '
      + CASE i.is_unique WHEN 1 THEN 'UNIQUE ' ELSE '' END
      + CASE i.[type] WHEN 1 THEN 'CLUSTERED ' ELSE '' END
      + ' INDEX ' + i.name + ' ON ' + QUOTENAME(@TableName) + ' (' 
      + dbo.BuildIndexColumns(@object_id, i.index_id, 0)
      + ')' + COALESCE(' INCLUDE(' 
      + dbo.BuildIndexColumns(@object_id, i.index_id, 1)
      + ')', '') + ';' + CHAR(13) + CHAR(10)
  FROM
      sys.indexes AS i
  WHERE
      i.[object_id] = @object_id
      -- since this will be covered by ScriptPKForTable:
      AND i.is_primary_key = 0
  ORDER BY i.index_id;

  SELECT COALESCE(@sql, ' ');
END
GO

请注意，我的解决方案并不承担PK是集群（集群的PK脚本硬编码，但那么你的脚本指数假定任何指标的可聚）。 我也忽略了其他属性，如文件组，分区，或过滤索引（2005年不支持反正）。



文章来源: Deadlock when querying INFORMATION_SCHEMA
标签： sql-server-2005 tsql
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