sql-server - SQL Server 2005 : Key-Range Locks in Read Committed Transaction Isolation Level?

Question

我正在帮助解决使用 SQL Server 2005 的 .NET 应用程序中的一些死锁问题。我有来自以下跟踪的 ​​XML 数据。

真正让我困惑的是 PK_Exp_Experience_PriorFirm 上的 RangeX-X 锁定当事务隔离级别为读提交时。

我读过的所有内容都表明您只能获得使用“可序列化”事务隔离级别的键范围锁。到目前为止，我在我们的应用程序中找不到任何地方将隔离级别设置为除已提交读以外的任何级别，并且下面的 XML 还表明我们正在使用已提交读。

但是，如果我们使用 read-committed，我不明白跟踪如何显示存在键范围锁定。有没有人有关于如何发生的想法？

<deadlock-list>
  <deadlock victim="processc2f438">
    <process-list>
      <process id="processc2f438" taskpriority="0" logused="13488" waitresource="KEY: 120:72057594583646208 (8201498b6efe)" waittime="484" ownerId="693258089" transactionname="user_transaction" lasttranstarted="2009-01-06T16:33:27.817" XDES="0xa71ce370" lockMode="U" schedulerid="1" kpid="9112" status="suspended" spid="53" sbid="0" ecid="0" priority="0" transcount="2" lastbatchstarted="2009-01-06T16:33:27.863" lastbatchcompleted="2009-01-06T16:33:27.863" clientapp=".Net SqlClient Data Provider" hostname="CHQAPT3" hostpid="6464" loginname="AppUser" isolationlevel="read committed (2)" xactid="693258089" currentdb="120" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
        <executionStack>
          <frame procname="adhoc" line="1" stmtstart="108" sqlhandle="0x0200000015d9962978fc6206b09e4c872150511b455e8923">
            UPDATE Exp_Experience_PriorFirm SET RelatedGuid = @newGuid WHERE RelatedGuid = @oldGuid
          </frame>
          <frame procname="mssqlsystemresource.sys.sp_executesql" line="1" sqlhandle="0x0400ff7fbe80662601000000000000000000000000000000">
            sp_executesql
          </frame>
          <frame procname="MyDb.dbo.Contact_MergeRelationships" line="74" stmtstart="4754" stmtend="4976" sqlhandle="0x0300780036a608461ed8af00669b00000100000000000000">
            EXEC sp_executesql @sql,
            N'@oldGuid uniqueidentifier, @newGuid uniqueidentifier',
            @oldGuid, @newGuid
          </frame>
          <frame procname="MyDb.dbo.Contact_Company_MergeRelationships" line="8" stmtstart="312" sqlhandle="0x03007800b271a129c8ccaf00669b00000100000000000000">
            EXEC Contact_MergeRelationships @oldGuid, @newGuid, 'Contact_Company', @excludedTableNames
          </frame>
        </executionStack>
        <inputbuf>
          Proc [Database Id = 120 Object Id = 698446258]
        </inputbuf>
      </process>
      <process id="processeb5d68" taskpriority="0" logused="14212" waitresource="KEY: 120:72057594594066432 (7c02a3a5890e)" waittime="2312" ownerId="693243114" transactionname="user_transaction" lasttranstarted="2009-01-06T16:33:20.957" XDES="0x8cdb9450" lockMode="S" schedulerid="2" kpid="9000" status="suspended" spid="73" sbid="0" ecid="0" priority="0" transcount="2" lastbatchstarted="2009-01-06T16:33:29.770" lastbatchcompleted="2009-01-06T16:33:29.770" clientapp=".Net SqlClient Data Provider" hostname="CHQAPT3" hostpid="6464" loginname="AppUser" isolationlevel="read committed (2)" xactid="693243114" currentdb="120" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056">
        <executionStack>
          <frame procname="MyDb.dbo.Contact_Company_Delete" line="27" stmtstart="1128" sqlhandle="0x03007800b0e5761877cbaf00669b00000100000000000000">
            DELETE FROM Contact WHERE GUID = @Guid;
          </frame>
        </executionStack>
        <inputbuf>
          Proc [Database Id = 120 Object Id = 410445232]
        </inputbuf>
      </process>
    </process-list>
    <resource-list>
      <keylock hobtid="72057594583646208" dbid="120" objectname="MyDb.dbo.Exp_Experience_PriorFirm" indexname="PK_Exp_Experience_PriorFirm" id="lockd1d43f80" mode="RangeX-X" associatedObjectId="72057594583646208">
        <owner-list>
          <owner id="processeb5d68" mode="RangeX-X"/>
        </owner-list>
        <waiter-list>
          <waiter id="processc2f438" mode="U" requestType="wait"/>
        </waiter-list>
      </keylock>
      <keylock hobtid="72057594594066432" dbid="120" objectname="MyDb.dbo.Contact_PersonCompanyLocation" indexname="PK_Contact_PersonCompanyLocation" id="lockd20c4380" mode="X" associatedObjectId="72057594594066432">
        <owner-list>
          <owner id="processc2f438" mode="X"/>
        </owner-list>
        <waiter-list>
          <waiter id="processeb5d68" mode="S" requestType="wait"/>
        </waiter-list>
      </keylock>
    </resource-list>
  </deadlock>
</deadlock-list>

Answer 1

PK_Exp_Experience_PriorFirm 上的 RangeX-X 锁定被用作级联删除的一部分。

对于某些操作，例如级联删除，SQL Server 会自动将隔离级别升级为可序列化。

这里有更详细的描述:Conor vs. Isolation Level Upgrade on UPDATE/DELETE Cascading RI .