I’ve strange deadlock graph where the victim chosen by MSSQL server 2008 isn’t part of the deadlock loop.
This deadlock is between select and insert.
The deadlock resource is a single table where all selects want waitresource = "KEY: 6:72057594098810880 (ffffffffffff)"
Question1 : Does ffffffffffff here mean they want a full range lock on whole table? Or whole key range? Or something else?
We are following a rule where table will never have a row with primary key id = 0.
There are few places where we do this kind of check
select foo from bar where @someId = 0 OR SomeId = @someId.
I also came to know about that SQL doesn’t short-circuit the expression. So if I pass @someId = 0 that doesn’t guarantee the other part won’t be evaluated. So it’s possible that SQL can execute at runtime SomeId = @someId.
Question2 : Since it wasn’t able to find 0 in SomeId, SQL will acquire a range lock on whole table (or row) so no one else inserts 0 id. Right?
With that assumption in mind I changed the where clause to this
(CASE
WHEN @someId = 0 THEN 1
WHEN SomeId = @someId THEN 1
ELSE 0
END = 1)
hoping that this will force evaluation order. But I’m wrong. I’m getting the deadlock again.
I’ve attached the deadlock graph below. I’ve renamed tables and sprocs involved (Company policy)
Question3 : Do you know what I’m missing here?
<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>
<process id="process7223048" taskpriority="0" logused="0" waitresource="KEY: 6:72057594098810880 (ffffffffffff)" waittime="5330" ownerId="24235090" transactionname="SELECT" lasttranstarted="2011-05-17T03:29:16.927" XDES="0x840d3b30" lockMode="RangeS-S" schedulerid="15" kpid="23452" status="suspended" spid="88" sbid="0" ecid="0" priority="0" trancount="0" lastbatchstarted="2011-05-17T03:29:16.927" lastbatchcompleted="2011-05-17T03:29:16.927" clientapp=".Net SqlClient Data Provider" hostname="SOMEHOST" hostpid="28820" loginname="someloginname" isolationlevel="serializable (4)" xactid="24235090" 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="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" />
</waiter-list>
</keylock>
<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" />
</waiter-list>
</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" />
</waiter-list>
</keylock>
<keylock hobtid="72057594098810880" dbid="6" objectname="TheOneTable" indexname="PK_TheOneTable" id="lock6b17a00" mode="RangeI-N" associatedObjectId="72057594098810880">
<owner-list />
<waiter-list>
<waiter id="process6334088" mode="RangeS-S" requestType="wait" />
</waiter-list>
</keylock>
<keylock hobtid="72057594098810880" dbid="6" objectname="TheOneTable" indexname="PK_TheOneTable" id="lock6b17a00" mode="RangeI-N" associatedObjectId="72057594098810880">
<owner-list>
<owner id="process5c08988" mode="RangeI-N" />
</owner-list>
<waiter-list>
<waiter id="process8808e08" mode="RangeS-S" requestType="wait" />
</waiter-list>
</keylock>
<keylock hobtid="72057594098810880" dbid="6" objectname="TheOneTable" indexname="PK_TheOneTable" id="lock6372e80" mode="RangeS-S" associatedObjectId="72057594098810880">
<owner-list>
<owner id="process7223048" mode="RangeS-S" />
<owner id="process6334088" mode="RangeS-S" />
</owner-list>
<waiter-list>
<waiter id="process5c08988" mode="RangeI-N" requestType="wait" />
</waiter-list>
</keylock>
</resource-list>
</deadlock>
</deadlock-list>
In the context of locking, tables and their related indexes are separate entities. At times, dead locking happens between a table and its index, rather than between two separate tables.
The problem is most likely when a lock is aquired on an index and then another lock is aquired on the related table (i.e. bar) to do the data lookup. During the insert, this will happen in the opposite order. First, the table (i.e. bar) is locked and updated, then indexes are locked.
Do you have/can you add a covering index (to help with the select) that contains both the SomeId and foo ? This way you’ll avoid the lookup altogether and stop the problem from occuring.
Can you post the query plans rather than deadlock frames?