早晨到办公室听同事说表被锁了，一试，发现表中某字段为1111111的行都被锁了，SELECT都不行。报错误ORA-01591，打开TOAD的KnowledgeeXpert，描述很少，只是说由于分布式事务错误而造成锁定。询问同事，昨天通过一个调用另一个存储过程出了错误，而后者通过透明网关insert一些数据到数据库。
立即想到打开OEM，谁知道大失所望，进入锁，根本没发现相关的对象被锁定，开始有点郁闷。转而检查会话，该用户有5个会话，都是INACTIVE，不管三七二十一，全部杀掉。结果依旧，并且锁也没有出现。远程登陆上主机，发现和都正常，也没有发现透明网关进程挂死（之前曾发现TG4SQL在无业务量时也会出现25%左右的CPU，挂死）。
突然想到看看alert.log，经过仔细搜索，终于发现：
WedNov1700:00:042004
Errorsinfiled:“oracle“admin“xdcj“udump“xdcj_j006_3020.trc:
ORA-12012:自动执行作业82出错
ORA-01591:锁定已被有问题的分配事务处理6.5.887985挂起
ORA-06512:在line6
这正是出错的地方，往前追溯：
TueNov1617:35:042004
Error28500trappedin2PContransaction6.5.887985.Cleaningup.
Errorstackreturnedtouser:
ORA-02054:事务处理6.5.887985有问题
ORA-28500:连接ORACLE到非Oracle系统时返回此:
[TransparentgatewayforMSSQL]
ORA-02063:紧接着2lines（源于ZSMOS_CRM）
TueNov1617:35:042004
DISTRIBTRANQDCJ.US.ORACLE.COM.5ae32328.6.5.887985
islocaltran6.5.887985
insertpendingpreparedtran，scn=6606197672830
TueNov1617:35:072004
Errorsinfiled:“oracle“admin“xdcj“bdump“xdcj_reco_3024.trc:
ORA-28500:connectionfromORACLEtoanon-Oraclesystemreturnedthismessage:
[TransparentgatewayforMSSQL][Microsoft][ODBCSQLServerDriver][SQLServer]用户'RECOVER'登录失败。
ORA-02063:preceding2linesfromZSMOS_CRM
TueNov1617:35:122004
Errorsinfiled:“oracle“admin“xdcj“bdump“xdcj_reco_3024.trc:
ORA-28500:connectionfromORACLEtoanon-Oraclesystemreturnedthismessage:
[TransparentgatewayforMSSQL][Microsoft][ODBCSQLServerDriver][SQLServer]用户'RECOVER'登录失败。
ORA-02063:preceding2linesfromZSMOS_CRM
这就是事发地点了。看来是昨天下午远程事务失败，但是又没有返回造成分布式事务挂死，从而锁定了行。终于找到了详细的错误ORA-02054，进入TOAD一查，说是要等待或者提交该事务，可是怎么操作呢。还是打开官方文档搜索相关内容，在AdminstratorGuide中发现如下内容：
DiscoveringProblemswithaTwo-PhaseCommit
Theuserapplicationthatcommitsadistributedtransactionisinformedofaproblembyoneofthefollowingerrormessages:
ORA-02050:transactionIDrolledback，
someremotedbsmaybein-doubt
ORA-02051:transactionIDcommitted，
someremotedbsmaybein-doubt
ORA-02054:transactionIDin-doubt
Arobustapplicationshouldsaveinformationaboutatransactionifitreceivesanyoftheaboveerrors.Thisinformationcanbeusedlaterifmanualdistributedtransactionrecoveryisdesired.
Noactionisrequiredbytheadministratorofanynodethathasoneormorein-doubtdistributedtransactionsduetoanetworkorsystemfailure.TheautomaticrecoveryfeaturesofOracletransparentlycompleteanyin-doubttransactionsothatthesameoutcomeoccursonallnodesofasessiontreeafterthenetworkorsystemfailureisresolved.
Inextendedoutages，however，youcanforcethecommitorrollbackofatransactiontoreleaseanylockeddata.Applicationsmustaccountforsuchpossibilities.
DeterminingWhethertoPerformaManualOverride
Overrideaspecificin-doubttransactionmanuallyonlywhenoneofthefollowingsituationsexists:
Thein-doubttransactionlocksdatathatisrequiredbyothertransactions.ThissituationoccurswhentheORA-01591errormessageinterfereswithusertransactions.
Anin-doubttransactionpreventstheextentsofarollbacksegmentfrombeingusedbyothertransactions.Thefirstportionofanin-doubtdistributedtransaction'slocaltransactionIDcorrespondstotheIDoftherollbacksegment，aslistedbythedatadictionaryviewsDBA_2PC_PENDINGandDBA_ROLLBACK_SEGS.
Thefailurepreventingthetwo-phasecommitphasestocompletecannotbecorrectedinanacceptabletimeperiod.Examplesofsuchcasesincludeatelecommunicationnetworkthathasbeendamagedoradamageddatabasethatrequiresalongrecoverytime.
Normally，youshouldmakeadecisiontolocallyforceanin-doubtdistributedtransactioninconsultationwithadministratorsatotherlocations.Awrongdecisioncanleadtodatabaseinconsistenciesthatcanbedifficulttotraceandthatyoumustmanuallycorrect.
Iftheconditionsabovedonotapply，alwaysallowtheautomaticrecoveryfeaturesofOracletocompletethetransaction.Ifanyoftheabovecriteriaaremet，however，consideralocaloverrideofthein-doubttransaction.
看来是建议差不多，后面Oracle总是试图登录SQlServer就是要自动恢复，可是总不成功。察看视图DBA_2PC_PENDING确实发现了该事务的痕迹。要怎样操作呢？
ManuallyCommittinganIn-DoubtTransaction
Beforeattemptingtocommitthetransaction，ensurethatyouhavetheproperprivileges.Notethefollowingrequirements:
Ifthetransactionwascommittedby...Thenyoumusthavethisprivilege...
You
FORCETRANSACTION
Anotheruser
FORCEANYTRANSACTION
CommittingUsingOnlytheTransactionID
ThefollowingSQLstatementcommitsanin-doubttransaction:
COMMITFORCE'transaction_id';
Thevariabletransaction_idistheidentifierofthetransactionasspecifiedineithertheLOCAL_TRAN_IDorGLOBAL_TRAN_IDcolumnsoftheDBA_2PC_PENDINGdatadictionaryview.
Forexample，assumethatyouqueryDBA_2PC_PENDINGanddeterminethatLOCAL_TRAN_IDforadistributedtransactionis1:45.13.
YouthenissuethefollowingSQLstatementtoforcethecommitofthisin-doubttransaction:
COMMITFORCE'1.45.13';
CommittingUsinganSCN
Optionally，youcanspecifytheSCNforthetransactionwhenforcingatransactiontocommit.Thisfeatureallowsyoutocommitanin-doubttransactionwiththeSCNassignedwhenitwascommittedatothernodes.
Consequently，youmaintainthesynchronizedcommittimeofthedistributedtransactionevenifthereisafailure.SpecifyanSCNonlywhenyoucandeterminetheSCNofthesametransactionalreadycommittedatanothernode.
Forexample，assumeyouwanttomanuallycommitatransactionwiththefollowingglobaltransactionID:
SALES.ACME.COM.55d1c563.1.93.29
First，querytheDBA_2PC_PENDINGviewofaremotedatabasealsoinvolvedwiththetransactioninquestion.NotetheSCNusedforthecommitofthetransactionatthatnode.SpecifytheSCNwhencommittingthetransactionatthelocalnode.Forexample，iftheSCNis829381993，issue:
COMMITFORCE'SALES.ACME.COM.55d1c563.1.93.29'，829381993;
SeeAlso:
Oracle9iSQLReferenceformoreinformationaboutusingtheCOMMITstatement
ManuallyRollingBackanIn-DoubtTransaction
Beforeattemptingtorollbackthein-doubtdistributedtransaction，ensurethatyouhavetheproperprivileges.Notethefollowingrequirements:
Ifthetransactionwascommittedby...Thenyoumusthavethisprivilege...
You
FORCETRANSACTION
Anotheruser
FORCEANYTRANSACTION
ThefollowingSQLstatementrollsbackanin-doubttransaction:
ROLLBACKFORCE'transaction_id';
Thevariabletransaction_idistheidentifierofthetransactionasspecifiedineithertheLOCAL_TRAN_IDorGLOBAL_TRAN_IDcolumnsoftheDBA_2PC_PENDINGdatadictionaryview.
Forexample，torollbackthein-doubttransactionwiththelocaltransactionIDof2.9.4，usethefollowingstatement:
ROLLBACKFORCE'2.9.4';
于是登陆数据库
COMMITFORCE'6.5.887985';
然后查看DBA_2PC_PENDING发现状态已经改为'COMMITFORCE'，SELECT该表相关行，一切正常。至此，故障解决。
总体来看，直接INSERT...TABLENAME@SQLDBLK还是很危险的，遇上不能正常返回就出问题了。Oracle的文档是推荐使用包或者存储过程来解决，此后建议同事改用此方法，目前已经测试通过。
