Duplicate Rows when using Continuous Incremental Updates and Partial Reload of Data on partitioned Tables.
The result set of a query may contain unexpected duplicate rows if data from partitioned tables in DB2 have been updated on the accelerator using partial reload.
Users of IBM DB2 Analytics Accelerator for z/OS
- Version 4.1.0, maintenance levels PTF-5 and PTF-6
- Version 5.1.0, maintenance levels GA, PTF-1, PTF-2, PTF-3, and PTF-4
may be affected if the following conditions are fulfilled:
‘Continuous incremental updates’ has been enabled.
- The DB2 tables synchronized with the accelerator using ‘Continuous incremental updates’ are partitioned.
- A partial reload of such tables on the accelerator has been performed or will be performed.
There is no way to determine in advance whether a partitioned table may cause the problem upon partial reload.
The function ‘Continuous incremental updates’ is not enabled by default. To determine whether the function has been enabled, use the IBM DB2 Analytics Accelerator Console and select ‘Continuous incremental updates’. The system displays the current configuration.
Resolving the problem
Apply PTF UI45775 (or its successor) solving APAR PI77397.
After restarting the CDC Capture Agent Task, fully reload all partitioned tables. If multiple accelerators are connected to the DB2 subsystem, do this on all accelerators. Use the SYSPROC.ACCEL_LOAD_TABLES stored procedure or the IBM DB2 Analytics Accelerator Studio for this purpose.
Note: A partial reload (for example with detectChanges="DATA") is not sufficient; the stored procedure must be run with forceFullReload="true".
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