Question

I have 2 queries that get involved in a deadlock situaution displayed in the Deadlockgraph below. (Seitensperre means pagelock)

The query in process 55 is the deadlock victim. It is a select that includes the tables order and payment.

The query on process 95 has a couple of queries in it
At the beginning ist does a couple of selects to store some values into variables (table order is accessed)
It then updates table order and after that table payment.

I dont understand how a deadlock can arise from this situation. Can you explain what the deadlock caused and what I can do about this? I guess I just have hard time reading the deadlock-graph.

Here are the resources involved.

<resource-list>
   <objectlock lockPartition="0" objid="1104059019" subresource="FULL" dbid="9" objectname="mycompany.dbo.order" id="lock1b9596980" mode="S" associatedObjectId="1104059019">
    <owner-list>
     <owner id="process443bac8" mode="S"/>
    </owner-list>
    <waiter-list>
     <waiter id="process20fc5eda8" mode="IX" requestType="wait"/>
    </waiter-list>
   </objectlock>
   <pagelock fileid="1" pageid="1825971" dbid="9" objectname="mycompany.dbo.Payment" id="lock1bca33000" mode="IX" associatedObjectId="72057594063159296">
    <owner-list>
     <owner id="process20fc5eda8" mode="IX"/>
    </owner-list>
    <waiter-list>
     <waiter id="process443bac8" mode="S" requestType="wait"/>
    </waiter-list>
   </pagelock>
  </resource-list>

EDIT

Here is the Update query (process 95)

ALTER   PROCEDURE [dbo].[updateOrderDetails]
(
    @id_order               int,
    @customerComment        NText,
    @salutationBilling      nvarchar(50) = '00',
    @companyNameBilling     nvarchar(100)= ''

        ...some more Parameters
)
AS
DECLARE @user_change int, @id_orderAddress int,
        @id_voucherType int, @id_orderPayment int, @id_paymentMode int


SET NOCOUNT ON;
SET ANSI_NULLS ON

SELECT @user_change = 0
SELECT @id_orderAddress = 0
SELECT @id_voucherType = 0
SELECT @id_orderPayment = 0
SELECT @id_paymentMode = 0


SELECT @user_change = id FROM user
 WHERE logonName = @user_str

SELECT @id_orderAddress = id_orderAddress FROM order
 WHERE [id] = @id_order

SELECT @id_voucherType = [id] FROM voucherType
 WHERE [name] = @voucherTypeName


SELECT @id_orderPayment = [id_orderPayment] FROM order 
 WHERE [id] = @id_order 

SELECT @id_paymentMode = [id] FROM paymentMode
 WHERE [name] = @paymentModeName


IF @user_change = 0 GOTO ERR
IF @id_voucherType = 0 GOTO ERR

UPDATE order
SET
[id_voucherType]        =       @id_voucherType,
[customerComment]       =       @customerComment,
[causeOfCancellation]   =       @causeOfCancellation
...some more fields to update

WHERE
[id] = @id_order

IF @id_orderAddress = 0 GOTO ERR

UPDATE Address
SET
[salutationBilling]     =    @salutationBilling,
[companyNameBilling]    =    @companyNameBilling,
[firstNameBilling]      =    @firstNameBilling
...some more fields to update
WHERE
[id] = @id_orderAddress

IF @id_orderPayment = 0 OR @id_paymentMode = 0 GOTO ERR
UPDATE Payment
SET
[id_paymentMode]        =   @id_paymentMode,
[customerBankDepositor] =   @customerBankDepositor,
[customerBank]          =   @customerBank,
[customerBankCode]      =   @customerBankCode,
...some more fields to update
WHERE
[id] = @id_orderPayment

IF @@Error > 0 Goto ERR


RETURN 0

ERR:

return  -1;
SET QUOTED_IDENTIFIER ON

Here is the select query (process 55)

ALTER  PROCEDURE [dbo].[searchOrders]
(
  @SelectType           INT
 ,@searchB2B            INT
 ,@VoucherNumber        NVARCHAR(50)  = null
 ,@FirstNameBilling     NVARCHAR(100) = null
    ... some more parameters
)

AS

SET NOCOUNT ON;

IF  @SelectType = 0 and LEN(@VoucherNumber) > 0
 BEGIN
    SELECT DISTINCT  (o.id)
                    ,o.voucherNumber
                    ...some more columns

    FROM             order AS o
    LEFT JOIN        orderAssignment AS oa  ON o.id = oa.id_order
    LEFT JOIN        voucherType AS vt      ON o.id_voucherType = vt.id
    LEFT JOIN        Payment AS op      ON o.id_orderPayment = op.id
    LEFT JOIN        paymentMode AS pm      ON op.id_paymentMode = pm.id
    LEFT JOIN        orderAddress AS addr   ON o.id_orderAddress = addr.id
    LEFT JOIN        user AS u1             ON o.user_change = u1.id
    LEFT JOIN        user as u2             ON oa.id_user = u2.id   
    LEFT JOIN        b2bAccount as b2b      ON o.id_b2bAccount = b2b.id


    WHERE            o.voucherNumber like @VoucherNumber
    AND              o.isB2B = @searchB2B
 END
...some more cases depending on @SelectType but the actual query is with @SelectType = 0

RETURN

SET ANSI_NULLS ON
SET QUOTED_IDENTIFIER ON

Answer 1

At the end it turned out that it was an issue with the calling code. Its difficult to explain, but basically a transaction was opened and handed over to a couple of methods.

I removed the transaction and the deadlocks went away.

Of course I have to re-implement the transaction again, and see if it is really a problem with how the transaction handling was implemented or if the transaction just spans for too long.