2

我有一个奇怪的死锁图，其中 MSSQL server 2008 选择的受害者不是死锁循环的一部分。这个死锁在select和之间insert。死锁资源是所有select需要的单个表waitresource = "KEY: 6:72057594098810880 (ffffffffffff)"

问题1：这里的 ffffffffffff 是否意味着他们想要在整个桌子上进行全范围锁定？还是整个键范围？或者是其他东西？

我们遵循一个规则，即表永远不会有主键 id = 0 的行。我们做这种检查的地方很少

select foo from bar where @someId = 0 OR SomeId = @someId.

我还了解到 SQL 不会使表达式短路。因此，如果我通过@someId = 0并不能保证其他部分不会被评估。所以 SQL 有可能在运行时执行SomeId = @someId。

问题2：由于无法在 SomeId 中找到 0，SQL 将在整个表（或行）上获取范围锁，因此没有其他人插入 0 id。正确的？

考虑到这个假设，我将 where 子句更改为此

(CASE
       WHEN @someId = 0 THEN 1
       WHEN SomeId = @someId THEN 1
       ELSE 0
END = 1)

希望这将强制评估顺序。但我错了。我又陷入僵局了。我在下面附上了死锁图。我已重命名所涉及的表和存储过程（公司政策）

问题3：你知道我在这里想念什么吗？

在此处输入图像描述

  <deadlock-list>
 <deadlock victim="process722c508">
  <process-list>
   <process id="process722c508" taskpriority="0" logused="0" waitresource="KEY: 6:72057594098810880 (ffffffffffff)" waittime="6217" ownerId="24219001" transactionname="SELECT" lasttranstarted="2011-05-17T03:29:16.033" XDES="0x80073a40" lockMode="RangeS-S" schedulerid="13" kpid="20436" status="suspended" spid="91" sbid="0" ecid="0" priority="0" trancount="0" lastbatchstarted="2011-05-17T03:29:16.033" lastbatchcompleted="2011-05-17T03:29:16.033" clientapp=".Net SqlClient Data Provider" hostname="SOMEHOST" hostpid="28820" loginname="someloginname" isolationlevel="serializable (4)" xactid="24219001" currentdb="6" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056">
    <executionStack>
     <frame procname="fnGetTableResultAByBId" line="44" stmtstart="2246" stmtend="3566" sqlhandle="0x03000600800d7f0bda124000d99e00000000000000000000">
INSERT INTO @ReturnTable
    SELECT Foo, Bar
    FROM TheOneTable 
    WHERE ZId = @zId 
    AND (CASE
            WHEN @yId = 0 THEN 1
            WHEN YId = @yId THEN 1
            ELSE 0
        END = 1)
    AND (CASE
            WHEN @xId = 0 THEN 1
            WHEN XId = @xId THEN 1
            ELSE 0
        END = 1)     </frame>
     <frame procname="GetViewCByDId" line="9" stmtstart="272" stmtend="2984" sqlhandle="0x03000600c21629025d8f3f00d99e00000100000000000000">
    </frame>
    </executionStack>
    <inputbuf>
Proc [Database Id = 6 Object Id = 36247234]    </inputbuf>
   </process>
   <process id="process7185048" taskpriority="0" logused="0" waitresource="KEY: 6:72057594098810880 (ffffffffffff)" waittime="6217" ownerId="24218992" transactionname="SELECT" lasttranstarted="2011-05-17T03:29:16.030" XDES="0x179980430" lockMode="RangeS-S" schedulerid="13" kpid="30616" status="suspended" spid="79" sbid="0" ecid="0" priority="0" trancount="0" lastbatchstarted="2011-05-17T03:29:16.030" lastbatchcompleted="2011-05-17T03:29:16.030" clientapp=".Net SqlClient Data Provider" hostname="SOMEHOST" hostpid="28820" loginname="someloginname" isolationlevel="serializable (4)" xactid="24218992" currentdb="6" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056">
    <executionStack>
     <frame procname="fnGetTableResultAByBId" line="44" stmtstart="2246" stmtend="3566" sqlhandle="0x03000600800d7f0bda124000d99e00000000000000000000">
INSERT INTO @ReturnTable
    SELECT Foo, Bar
    FROM TheOneTable 
    WHERE ZId = @zId 
    AND (CASE
            WHEN @yId = 0 THEN 1
            WHEN YId = @yId THEN 1
            ELSE 0
        END = 1)
    AND (CASE
            WHEN @xId = 0 THEN 1
            WHEN XId = @xId THEN 1
            ELSE 0
        END = 1)     </frame>
     <frame procname="GetViewCByDId" line="9" stmtstart="272" stmtend="2984" sqlhandle="0x03000600c21629025d8f3f00d99e00000100000000000000">
</frame>
    </executionStack>
    <inputbuf>
Proc [Database Id = 6 Object Id = 36247234]    </inputbuf>
   </process>
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    <executionStack>
     <frame procname="GetOneRowEByFId" line="11" stmtstart="260" stmtend="2456" sqlhandle="0x03000600db082c08ba823f00d99e00000100000000000000">
         SELECT TOP 1
         Col1, Col2, Col3

         FROM The2ndTable
         INNER JOIN [dbo].[TheOneTable] ON [dbo].[TheOneTable].[LinkBetweenOneAndTwoId]=[The2ndTable].[LinkBetweenOneAndTwoId]
         WHERE [dbo].[TheOneTable].ZId= @ActivityId and
         [TheOneTable].[n
     </frame>
    </executionStack>
    <inputbuf>
Proc [Database Id = 6 Object Id = 137103579]    </inputbuf>
   </process>
   <process id="process6334088" taskpriority="0" logused="0" waitresource="KEY: 6:72057594098810880 (ffffffffffff)" waittime="5668" ownerId="24229434" transactionname="SELECT" lasttranstarted="2011-05-17T03:29:16.587" XDES="0x17ea9ac90" lockMode="RangeS-S" schedulerid="12" kpid="5104" status="suspended" spid="86" sbid="0" ecid="0" priority="0" trancount="0" lastbatchstarted="2011-05-17T03:29:16.587" lastbatchcompleted="2011-05-17T03:29:16.587" clientapp=".Net SqlClient Data Provider" hostname="SOMEHOST" hostpid="28820" loginname="someloginname" isolationlevel="serializable (4)" xactid="24229434" currentdb="6" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056">
    <executionStack>
     <frame procname="GetOneRowEByFId" line="11" stmtstart="260" stmtend="2456" sqlhandle="0x03000600db082c08ba823f00d99e00000100000000000000">
SELECT TOP 1 
    Col1, Col2, Col3

    FROM The2ndTable
    INNER JOIN [dbo].[TheOneTable] ON [dbo].[TheOneTable].[LinkBetweenOneAndTwoId]=[The2ndTable].[LinkBetweenOneAndTwoId]
    WHERE [dbo].[TheOneTable].ZId= @ActivityId and
        [TheOneTable].[n</frame>
    </executionStack>
    <inputbuf>
Proc [Database Id = 6 Object Id = 137103579]    </inputbuf>
   </process>
   <process id="process8808e08" taskpriority="0" logused="0" waitresource="KEY: 6:72057594098810880 (ffffffffffff)" waittime="6652" ownerId="24217112" transactionname="SELECT" lasttranstarted="2011-05-17T03:29:15.610" XDES="0x833b5ca0" lockMode="RangeS-S" schedulerid="1" kpid="19752" status="suspended" spid="89" sbid="0" ecid="0" priority="0" trancount="0" lastbatchstarted="2011-05-17T03:29:15.610" lastbatchcompleted="2011-05-17T03:29:15.610" clientapp=".Net SqlClient Data Provider" hostname="SOMEHOST" hostpid="28820" loginname="someloginname" isolationlevel="serializable (4)" xactid="24217112" currentdb="6" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056">
    <executionStack>
     <frame procname="GetOneRowEByFId" line="11" stmtstart="260" stmtend="2456" sqlhandle="0x03000600db082c08ba823f00d99e00000100000000000000">
         SELECT TOP 1
         Col1, Col2, Col3

         FROM The2ndTable
         INNER JOIN [dbo].[TheOneTable] ON [dbo].[TheOneTable].[LinkBetweenOneAndTwoId]=[The2ndTable].[LinkBetweenOneAndTwoId]
         WHERE [dbo].[TheOneTable].ZId= @ActivityId and
         [TheOneTable].[n
     </frame>
    </executionStack>
    <inputbuf>
Proc [Database Id = 6 Object Id = 137103579]    </inputbuf>
   </process>
   <process id="process5c08988" taskpriority="0" logused="1644" waitresource="KEY: 6:72057594098810880 (91a0638558d2)" waittime="4889" ownerId="24214248" transactionname="user_transaction" lasttranstarted="2011-05-17T03:29:15.327" XDES="0x186609470" lockMode="RangeI-N" schedulerid="9" kpid="9000" status="suspended" spid="102" sbid="0" ecid="0" priority="0" trancount="2" lastbatchstarted="2011-05-17T03:29:15.330" lastbatchcompleted="2011-05-17T03:29:15.330" clientapp=".Net SqlClient Data Provider" hostname="SOMEHOST" hostpid="28820" loginname="someloginname" isolationlevel="serializable (4)" xactid="24214248" currentdb="6" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056">
    <executionStack>
     <frame procname="InsertIntoTheOneTable" line="25" stmtstart="1334" stmtend="2608" sqlhandle="0x03000600bbbacb5d25883f00d99e00000100000000000000">
INSERT INTO [dbo].[TheOneTable] (Some,Col,Here)
    VALUES (@some,@col,@here)     </frame>
    </executionStack>
    <inputbuf>
Proc [Database Id = 6 Object Id = 1573632699]    </inputbuf>
   </process>
  </process-list>
  <resource-list>
   <keylock hobtid="72057594098810880" dbid="6" objectname="TheOneTable" indexname="PK_TheOneTable" id="lock6b17a00" mode="RangeI-N" associatedObjectId="72057594098810880">
    <owner-list />
    <waiter-list>
     <waiter id="process722c508" mode="RangeS-S" requestType="wait" />
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   <keylock hobtid="72057594098810880" dbid="6" objectname="TheOneTable" indexname="PK_TheOneTable" id="lock6b17a00" mode="RangeI-N" associatedObjectId="72057594098810880">
    <owner-list />
    <waiter-list>
     <waiter id="process7185048" mode="RangeS-S" requestType="wait" />
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   </keylock>
   <keylock hobtid="72057594098810880" dbid="6" objectname="TheOneTable" indexname="PK_TheOneTable" id="lock6b17a00" mode="RangeI-N" associatedObjectId="72057594098810880">
    <owner-list />
    <waiter-list>
     <waiter id="process7223048" mode="RangeS-S" requestType="wait" />
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    <owner-list />
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  </resource-list>
 </deadlock>
</deadlock-list>
4

2 回答 2

3

在锁定的上下文中，表及其相关索引是独立的实体。有时，死锁发生在一个表和它的索引之间，而不是两个单独的表之间。

当在索引上获取锁，然后在相关表（即 bar）上获取另一个锁以进行数据查找时，最有可能出现问题。在插入期间，这将以相反的顺序发生。首先，表（即 bar）被锁定和更新，然后索引被锁定。

select foo 
from bar 
where @someId = 0 OR SomeId = @someId

您是否有/可以添加包含 SomeId 和 foo 的覆盖索引（以帮助选择）？这样，您将完全避免查找并阻止问题发生。

您可以发布查询计划而不是死锁帧吗？

于 2011-05-22T05:36:16.020 回答
0

你介意尝试一些替代标准吗？我最近一直在使用这种方法（只是我使用 NULLs 而不是 0 来表示所有值）：

SET @yId = NullIf(@yId, 0);
SET @xId = NullIf(@xId, 0);

...
WHERE
   @yId BETWEEN Coalesce(@yId, 0) AND Coalesce(@yId, 2147483647)
   AND @xId BETWEEN Coalesce(@xId, 0) AND Coalesce(@xId, 2147483647)

或者你可以完整地使用你的零：

WHERE
   @yId BETWEEN @yId AND Coalesce(NullIf(@yId, 0), 2147483647)
   AND @xId BETWEEN @xId AND Coalesce(NullIf(@xId, 0), 2147483647)

再想一想……只是回顾一下，死锁只是因为资源获取顺序冲突而发生的。一个资源不仅仅是一个表，还包括行、范围、页面等。如果同时提交两个查询，最初获得一个较小粒度的锁，那么将它们的锁升级到与另一个进程拥有的较小锁重叠的东西，然后你会陷入僵局。

那么，有没有什么办法可以提前获取更大的锁，避免获取更大的冲突锁，或者改变资源获取顺序呢？

您可以尝试使用WITH (TABLOCKX)which 听起来很可怕，但是如果您的 @yId 或 @xId 为 0 从而使您选择所有行，那么无论如何您都将需要整个表。

您是否也考虑过尝试OPTION (MAXDOP 1)看看它是否有帮助？从理论上讲，同一数据请求具有多个流可能会增加同时获取冲突锁的可能性。

表是否有聚集索引？如果没有，添加它，如果是，它是被使用还是你可以强制它被使用？这可能会使查询以不同的方式访问表，从而防止死锁。

发表您的评论，我会根据您的回复查看是否有更多想法。

于 2011-05-22T04:04:10.683 回答