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DB2 LOCKSIZE=ANY - DEADLOCKS


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vasanthz

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Joined: 28 Aug 2007
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Location: Tiruppur, India

PostPosted: Sat Jul 07, 2018 12:02 am
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Hi,

We are facing deadlocks in a DB2 table and the table is created with LOCKSIZE=ANY.

Manual says that ANY lets DB2 choose the locking size.

Is it possible to determine what LOCKSIZE was chosen by DB2 during a period of deadlock. We have BMC DB2 tools and SMF.

Regards,
Vasanth.S
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Rohit Umarjikar

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Joined: 21 Sep 2010
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PostPosted: Mon Jul 09, 2018 11:41 pm
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Usually it will be LOCKSIZE PAGE
Change to LOCKSIZE ROW and watch , if you see frequent contention.
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vasanthz

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PostPosted: Tue Jul 10, 2018 1:31 am
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Thank you.
Would it be ok to change it to ROW without identifying what level locking was used prior to the deadlock. I thought we could go one lower level of lock than the lock that caused deadlocks
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Rohit Umarjikar

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PostPosted: Wed Jul 11, 2018 9:30 pm
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LOCKSIZE ROW is the lower level than LOCKSIZE PAGE. I don't think LOCKSIZE ANY would use LOCKSIZE ROW by itself in a situations like when LOCKSIZE PAGE is not sufficient.

I would look at LOCK ESCALATIONS too to know what it is defined.

This is my understanding but double check with DBA and if its different than above then I would learn something.
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PeterHolland

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Joined: 27 Oct 2009
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Location: Netherlands, Amstelveen

PostPosted: Thu Jul 12, 2018 3:14 pm
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The Keys to Understanding Locking for DB2 for zOS (PDF alert)

share.confex.com/share/121/webprogram/Handout/Session13956/The%20Keys%20to%20Understanding%20Locking.pdf
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vasanthz

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PostPosted: Fri Jul 13, 2018 3:05 am
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Thanks Rohit and Peter. I will review the information provided
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