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POdeadlock between two select statements
 

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  1. POdeadlock between two select statements
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    <p>I have two SQL select statements that are deadlocking.. I was under the impression that selects could not deadlock with each other?</p> <p>It is also puzzling that the query takes page locks on a select statement, could the indexes be causing this?</p> <p><img src="https://i.stack.imgur.com/0IYTo.png" alt="table Description"></p> <pre><code>&lt;deadlock-list&gt; &lt;deadlock victim="process1cf0ce928"&gt; &lt;process-list&gt; &lt;process id="process1cf0ce928" taskpriority="0" logused="8580" waitresource="PAGE: 11:1:168082 " waittime="4116" ownerId="24335138" transactionname="user_transaction" lasttranstarted="2013-10-01T23:04:04.353" XDES="0x2aa2f8d28" lockMode="S" schedulerid="2" kpid="6356" status="suspended" spid="62" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2013-10-01T23:04:06.907" lastbatchcompleted="2013-10-01T23:04:06.903" lastattention="1900-01-01T00:00:00.903" clientapp=".Net SqlClient Data Provider" hostname="******" hostpid="5892" loginname="*****" isolationlevel="read committed (2)" xactid="24335138" currentdb="11" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056"&gt; &lt;executionStack&gt; &lt;frame procname="DB.dbo.GetCommandById" line="22" stmtstart="1586" stmtend="1726" sqlhandle="0x03000b00edb44b1eebd677013da2000001000000000000000000000000000000000000000000000000000000"&gt; SELECT Top 1 * FROM [Commands] WHERE [Command_ID] = @CmdId; &lt;/frame&gt; &lt;/executionStack&gt; &lt;inputbuf&gt; Proc [Database Id = 11 Object Id = 508277997] &lt;/inputbuf&gt; &lt;/process&gt; &lt;process id="process1caa24cf8" taskpriority="0" logused="9876" waitresource="PAGE: 11:1:168082 " waittime="4104" ownerId="24335088" transactionname="user_transaction" lasttranstarted="2013-10-01T23:04:04.180" XDES="0x24f9956a8" lockMode="S" schedulerid="2" kpid="3872" status="suspended" spid="52" sbid="0" ecid="0" priority="0" trancount="1" lastbatchstarted="2013-10-01T23:04:06.917" lastbatchcompleted="2013-10-01T23:04:06.903" lastattention="1900-01-01T00:00:00.903" clientapp=".Net SqlClient Data Provider" hostname="*****" hostpid="5892" loginname="*****" isolationlevel="read committed (2)" xactid="24335088" currentdb="11" lockTimeout="4294967295" clientoption1="673185824" clientoption2="128056"&gt; &lt;executionStack&gt; &lt;frame procname="DB.dbo.GetCommandById" line="22" stmtstart="1586" stmtend="1726" sqlhandle="0x03000b00edb44b1eebd677013da2000001000000000000000000000000000000000000000000000000000000"&gt; SELECT Top 1 * FROM [Commands] WHERE [Command_ID] = @CmdId; &lt;/frame&gt; &lt;/executionStack&gt; &lt;inputbuf&gt; Proc [Database Id = 11 Object Id = 508277997] &lt;/inputbuf&gt; &lt;/process&gt; &lt;/process-list&gt; &lt;resource-list&gt; &lt;pagelock fileid="1" pageid="168082" dbid="11" subresource="FULL" objectname="DB.dbo.Commands" id="lock22626c880" mode="IX" associatedObjectId="72057795337322496"&gt; &lt;owner-list&gt; &lt;owner id="process1caa24cf8" mode="IX"/&gt; &lt;owner id="process1caa24cf8" mode="S" requestType="convert"/&gt; &lt;/owner-list&gt; &lt;waiter-list&gt; &lt;waiter id="process1cf0ce928" mode="S" requestType="convert"/&gt; &lt;/waiter-list&gt; &lt;/pagelock&gt; &lt;pagelock fileid="1" pageid="168082" dbid="11" subresource="FULL" objectname="DB.dbo.Commands" id="lock22626c880" mode="IX" associatedObjectId="72057795337322496"&gt; &lt;owner-list&gt; &lt;owner id="process1cf0ce928" mode="IX"/&gt; &lt;owner id="process1cf0ce928" mode="S" requestType="convert"/&gt; &lt;/owner-list&gt; &lt;waiter-list&gt; &lt;waiter id="process1caa24cf8" mode="S" requestType="convert"/&gt; &lt;/waiter-list&gt; &lt;/pagelock&gt; &lt;/resource-list&gt; &lt;/deadlock&gt; &lt;/deadlock-list&gt; </code></pre>
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    1. PTQuestion
    1. USsavagepanda
    1. USsavagepanda
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    1. COprocname="DB.dbo.GetCommandById" line="22" ==> in the end its transactions not statements that deadlock, what else is going in the first 21 lines of GetCommandById and what else is going on in the calling logic that might be carrying uncommitted change>.
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      1. POdeadlock between two select statements
      1. UStolanj
    2. COAgree with tolanj. The IX lock is an intent exclusive lock, and is probably created earlier in the process. A simple SELECT alone will not create that kind of lock, so we need to look elsewhere.
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      1. POdeadlock between two select statements
      1. USDeanG
    3. COCheck if you have uncommited transactional
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      1. POdeadlock between two select statements
      1. USAmir Keshavarz
 

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