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2810379 - LOCK TABLE... IN WRITE MODE WAIT command sequence is not honored - SAP IQ

Symptom

  • Several processes requiring to write to the same table issue a LOCK TABLE ... IN WRITE MODE command one after another.
  • Their lock requests are not honored by IQ 16.0 in the order they get received.
  • A process requesting a lock later may get it granted earlier than another one requesting a lock earlier. For example:

Process P1 is actively writing to table tab1
10:17:52am Process P2 requests a lock: LOCK TABLE tab1 IN WRITE MODE WAIT '01:00:00'
11:07:15am Process P3 requests a lock: LOCK TABLE tab1 IN WRITE MODE WAIT '01:00:00'
11:36:25am Process P3 gets a lock and proceeds with its work
11:36:25am Process P2 fails to acquire a lock.

   We would expect Process P2 to get its lock first and  Process P3 waiting in line as it came later, but that's not the case.


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Environment

SAP IQ 16.x

Product

SAP IQ 16.0 ; SAP IQ 16.1

Keywords

commit, expire, queue , KBA , BC-SYB-IQ , Sybase IQ , Problem

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