为什么我有这个SQL Server死锁？包括T1222的死锁痕迹

Question

我有一个死锁，但我不明白为什么。消息结尾是T1222踪迹。这是发生了什么：

UPDATE ADMISSIONS SET … 
LAUNCHS A TRIGGER - > INSERT INTO PCM_RECENTCHANGES … 
LAUNCHS A TRIGGER -> CALL FUNCTION GETLASTLOCATION 
THE FUNCTION EXECUTES -> SELECT TOP 1 @ENVIRONMENT = ENVIRONMENTDBOID 

有时，当我们有几台计算机做同样的事情时，我们得到下面报告的死锁。我没有得到的是，如果这只是一个读取查询，并且据我所知，没有人在该表上插入数据，我们如何在SELECT TOP 1 @ENVIRONMENT = ENVIRONMENTDBOID中产生死锁。

死锁报告：

deadlock-list 
    deadlock victim=processd99ab0 
    process-list 
    process id=processd99ab0 taskpriority=0 logused=11760 waitresource=RID: 8:7:765:0 waittime=2249 ownerId=6288074 transactionname=user_transaction lasttranstarted=2011-10-25T15:38:43.667 XDES=0x262dec08 lockMode=S schedulerid=3 kpid=2692 status=suspended spid=65 sbid=0 ecid=0 priority=0 trancount=2 lastbatchstarted=2011-10-25T15:38:43.710 lastbatchcompleted=2011-10-25T15:38:43.710 lastattention=2011-10-25T15:37:34.667 clientapp=Careman hostname=BCNW-ISOLER hostpid=4400 loginname=PicisSQL isolationlevel=read committed (2) xactid=6288074 currentdb=8 lockTimeout=4294967295 clientoption1=537002016 clientoption2=128056 
    executionStack 
     frame procname=NTPA_TEST_CAR.dbo.GETLASTLOCATION line=83 stmtstart=4218 stmtend=4478 sqlhandle=0x03000800ac4d05647a42db00819f00000000000000000000 
SELECT TOP 1 @ENVIRONMENT = ENVIRONMENTDBOID 
           FROM ENVIRONMENTS 
           WHERE ENCOUNTERDBOID = @ENCOUNTER 
           ORDER BY STARTED DESC  
     frame procname=NTPA_TEST_CAR.dbo.GETFACILITYBYTABLEDBOID line=31 stmtstart=1492 stmtend=1598 sqlhandle=0x03000800318fdd145641db00819f00000000000000000000 
SELECT @ret = dbo.GETLASTLOCATION('ADMISSION', @id)  
     frame procname=NTPA_TEST_CAR.dbo.TR_PCM_RECENTCHANGES_INSTEAD line=60 stmtstart=7396 stmtend=8576 sqlhandle=0x0300080062bc4b452d42db00819f00000000000000000000 
INSERT PCM_RECENTCHANGES (STARTED, ISDELETED, TABLENAME, PCM_KEY, PCM_MESSAGE, PATIENTDBOID, ENCOUNTERDBOID,FILTERID, FACILITYDBOID) 
           SELECT inserted.STARTED, inserted.ISDELETED, inserted.TABLENAME, inserted.PCM_KEY, inserted.PCM_MESSAGE, inserted.PATIENTDBOID, inserted.ENCOUNTERDBOID,'ADT', CASE WHEN inserted.FACILITYDBOID IS NOT NULL THEN inserted.FACILITYDBOID ELSE dbo.GETFACILITYBYTABLEDBOID(TABLENAME, CASE WHEN inserted.TABLENAME = 'PATIENTS' THEN inserted.PATIENTDBOID ELSE inserted.PCM_KEY END) END 
           FROM inserted 
           -- EXIT BECAUSE WE DO NOT HAVE ANYTHING ELSE TO DO.  
     frame procname=NTPA_TEST_CAR.dbo.TR_ADMISSIONS_IU line=169 stmtstart=21690 stmtend=27250 sqlhandle=0x03000800b9db99535642db00819f00000000000000000000 
INSERT INTO PCM_RECENTCHANGES (STARTED, ISDELETED, TABLENAME, PCM_KEY, PCM_MESSAGE) 
         SELECT  GetDate(), 
           'F', 
           'ADMISSIONS', 
           CONVERT(CHAR(21), i.ADMISSIONDBOID), 
           ISNULL(CONVERT(CHAR(48), A.ADMID1), REPLICATE(' ', 48)) 
            + ISNULL(CONVERT(CHAR(48), i.ADMID2), REPLICATE(' ', 48)) 
            + ISNULL(CONVERT(CHAR(48), i.ADMID3), REPLICATE(' ', 48)) 
            + ISNULL(CONVERT(CHAR(19), i.HOSPITALSTARTED, 120), REPLICATE(' ', 19)) 
            + ISNULL(CONVERT(CHAR(19), i.ENDED, 120), REPLICATE(' ', 19)) 
            + ISNULL(CONVERT(CHAR(19), i.PREADMISSION, 120), REPLICATE(' ', 19)) 
            + ISNULL(CONVERT(CHAR(13), i.WEIGHT), REPLICATE(' ', 13)) 
            +  
     frame procname=adhoc line=1 stmtstart=94 sqlhandle=0x0200000070ece538900ddb307676a81ad422678baf24495d 
UPDATE [ADMISSIONS] set [ENDED] = @1,[DISCHDBOID] = @2 WHERE [ADMISSIONDBOID]=@3  
     frame procname=adhoc line=1 sqlhandle=0x0200000026f85e24d2ee570e5908604daf7249bd6d4e9032 
update ADMISSIONS set ENDED={ts '2011-10-25 15:38:42'},DISCHDBOID=009000000000000000000 where ADMISSIONDBOID=004511105043973019010  
    inputbuf 
update ADMISSIONS set ENDED={ts '2011-10-25 15:38:42'},DISCHDBOID=009000000000000000000 where ADMISSIONDBOID=004511105043973019010  
    process id=processfc2c70 taskpriority=0 logused=13584 waitresource=RID: 8:7:758:8 waittime=2233 ownerId=6288077 transactionname=user_transaction lasttranstarted=2011-10-25T15:38:43.670 XDES=0xa228550 lockMode=S schedulerid=4 kpid=4340 status=suspended spid=86 sbid=0 ecid=0 priority=0 trancount=2 lastbatchstarted=2011-10-25T15:38:43.723 lastbatchcompleted=2011-10-25T15:38:43.720 lastattention=2011-10-25T15:37:36.140 clientapp=Careman hostname=BCNW-DANIM hostpid=13812 loginname=PicisSQL isolationlevel=read committed (2) xactid=6288077 currentdb=8 lockTimeout=4294967295 clientoption1=537002016 clientoption2=128056 
    executionStack 
    frame procname=NTPA_TEST_CAR.dbo.GETLASTLOCATION line=83 stmtstart=4218 stmtend=4478 sqlhandle=0x03000800ac4d05647a42db00819f00000000000000000000 
SELECT TOP 1 @ENVIRONMENT = ENVIRONMENTDBOID 
          FROM ENVIRONMENTS 
          WHERE ENCOUNTERDBOID = @ENCOUNTER 
          ORDER BY STARTED DESC  
    frame procname=NTPA_TEST_CAR.dbo.GETFACILITYBYTABLEDBOID line=31 stmtstart=1492 stmtend=1598 sqlhandle=0x03000800318fdd145641db00819f00000000000000000000 
SELECT @ret = dbo.GETLASTLOCATION('ADMISSION', @id)  
    frame procname=NTPA_TEST_CAR.dbo.TR_PCM_RECENTCHANGES_INSTEAD line=60 stmtstart=7396 stmtend=8576 sqlhandle=0x0300080062bc4b452d42db00819f00000000000000000000 
INSERT PCM_RECENTCHANGES (STARTED, ISDELETED, TABLENAME, PCM_KEY, PCM_MESSAGE, PATIENTDBOID, ENCOUNTERDBOID,FILTERID, FACILITYDBOID) 
          SELECT inserted.STARTED, inserted.ISDELETED, inserted.TABLENAME, inserted.PCM_KEY, inserted.PCM_MESSAGE, inserted.PATIENTDBOID, inserted.ENCOUNTERDBOID,'ADT', CASE WHEN inserted.FACILITYDBOID IS NOT NULL THEN inserted.FACILITYDBOID ELSE dbo.GETFACILITYBYTABLEDBOID(TABLENAME, CASE WHEN inserted.TABLENAME = 'PATIENTS' THEN inserted.PATIENTDBOID ELSE inserted.PCM_KEY END) END 
           FROM inserted 
           -- EXIT BECAUSE WE DO NOT HAVE ANYTHING ELSE TO DO.  
     frame procname=NTPA_TEST_CAR.dbo.TR_ADMISSIONS_IU line=169 stmtstart=21690 stmtend=27250 sqlhandle=0x03000800b9db99535642db00819f00000000000000000000 
INSERT INTO PCM_RECENTCHANGES (STARTED, ISDELETED, TABLENAME, PCM_KEY, PCM_MESSAGE) 
         SELECT  GetDate(), 
           'F', 
           'ADMISSIONS', 
           CONVERT(CHAR(21), i.ADMISSIONDBOID), 
           ISNULL(CONVERT(CHAR(48), A.ADMID1), REPLICATE(' ', 48)) 
            + ISNULL(CONVERT(CHAR(48), i.ADMID2), REPLICATE(' ', 48)) 
            + ISNULL(CONVERT(CHAR(48), i.ADMID3), REPLICATE(' ', 48)) 
            + ISNULL(CONVERT(CHAR(19), i.HOSPITALSTARTED, 120), REPLICATE(' ', 19)) 
            + ISNULL(CONVERT(CHAR(19), i.ENDED, 120), REPLICATE(' ', 19)) 
            + ISNULL(CONVERT(CHAR(19), i.PREADMISSION, 120), REPLICATE(' ', 19)) 
            + ISNULL(CONVERT(CHAR(13), i.WEIGHT), REPLICATE(' ', 13)) 
            +  
     frame procname=adhoc line=1 stmtstart=94 sqlhandle=0x0200000070ece538900ddb307676a81ad422678baf24495d 
UPDATE [ADMISSIONS] set [ENDED] = @1,[DISCHDBOID] = @2 WHERE [ADMISSIONDBOID]=@3  
     frame procname=adhoc line=1 sqlhandle=0x02000000ea3b4a253048c290f000fae3e15fc38eacf905c7 
update ADMISSIONS set ENDED={ts '2011-10-25 15:38:43'},DISCHDBOID=009000000000000000000 where ADMISSIONDBOID=004511105044149020010  
    inputbuf 
update ADMISSIONS set ENDED={ts '2011-10-25 15:38:43'},DISCHDBOID=009000000000000000000 where ADMISSIONDBOID=004511105044149020010  
    resource-list 
    ridlock fileid=7 pageid=765 dbid=8 objectname=NTPA_TEST_CAR.dbo.ENVIRONMENTS id=lock1ae5d240 mode=X associatedObjectId=64466095439872 
    owner-list 
     owner id=processfc2c70 mode=X 
    waiter-list 
     waiter id=processd99ab0 mode=S requestType=wait 
    ridlock fileid=7 pageid=758 dbid=8 objectname=NTPA_TEST_CAR.dbo.ENVIRONMENTS id=lock1afaf540 mode=X associatedObjectId=64466095439872 
    owner-list 
     owner id=processd99ab0 mode=X 
    waiter-list 
     waiter id=processfc2c70 mode=S requestType=wait 

Answer 1

出于某种原因，交易双方对ENVIRONMENTS的X锁。

可能存在与ADMISSIONS或者也许X锁由同一事务运行之前的一份声明获取，并且没有任何关系在所有（僵局报告中显示的代码on update cascade外键关系这说明语句在发生死锁时执行，而不是首先获取资源的语句）。

Answer 2

如果环境中缓慢变化的数据，则可以考虑的环境的表使用

with (NOLOCK) 

。这将降低发生死锁的风险。其次，你也可以删除ORDER BY，因为它不被使用。

接下来，您也可以考虑改写这一节，如：

if exists(select top 1 1 FROM ENVIRONMENTS WHERE ENCOUNTERDBOID = @ENCOUNTER) 
set @Environment = @Encounter 

你的SQL将始终设置@ENVIRONMENT到@ENCOUNTER时至少有一个排，在表格ENVIRONMENTS资格。无需排序，因为值集始终等于@ENCOUNTER，并且STARTED不会返回。

我列出了这些解决方案，因为它们都可以导致死锁情况。