PH59820: WITH ACCELERATOR MNT. LVL 7.5.12 LOAD OPERATIONS CAN FINISH WITHRC 0 AND A SUCCESS MESSAGE WHILE THE DATA LOADED IS NOT COMPLETE

APAR status

• Closed as documentation error.

Error description

• With accelerator maintenance level 7.5.12, tasks such as
  - Load or reload of an accelerator-shadow table (partition)
  - Full table reload
  - Load into an AOT (using the external load function of the
    Accelerator Loader)
  - Archiving of a table
  
  can finish with RC 0 and a success message while the data loaded
  is not complete.
  The issue can happen in rare cases when the workload is very
  high and when the database of the accelerator gets under stress.
  
  Background information:
  With accelerator maintenance level 7.5.12, we have delivered a
  couple of changes of the load component to reduce the number of
  situations where customers in the past had reported a load hang
  situation. Unfortunately, our regression and stress tests did
  not catch an erroneous code path processing a situation where
  the accelerator is waiting for the database to indicate a Go for
  the transmission of data.
  
  Recommendations / Mitigation / Determine whether you are
  affected:
  - If you are planning to upgrade your Accelerator maintenance
    level to 7.5.12, we kindly ask you to reconsider your schedule
    and postpone the upgrade until maintenance level 7.5.12.1 will
    be available.
  - If you are already running Accelerator maintenance level
    7.5.12, we recommend considering validity checks of
    accelerator-shadow tables having been loaded based on the
    following information:
    the ACCEL_LOAD_TABLES stored procedure message 'AQT20014 The
    following data was transferred ...' contains the amount of
    data received (in MB) and the number of rows inserted to the
    accelerator-shadow table.
    If this number looks suspicious meaning it is too low or 0, we
    recommend to compare the number of rows on the
    accelerator-shadow table with the one of the corresponding
    table in Db2 for z/OS (using SELECT COUNT(*) as validity
    check).
  
  Fixing the bug / delivering the solution:
  We will deliver the fix as Accelerator maintenance level
  7.5.12.1. This code level consists of the maintenance level
  7.5.12 amended by the few lines of code in the error handling of
  the load component. No other changes are packed into this
  maintenance level.
  The 7.5.12.1 installation package is planned to be completed on
  February 16, 2024. We plan to release it on February 21, 2024
  after the necessary tests have been completed.
  If you want to receive the installation package prior to its
  availability on Fix Central and our completion of the final
  tests, please contact IBM support using a new support case. We
  will upload the package to the subject case.
  
  Additional keywords:
  TS015405726 TS013721232 TS015461967 #idaa7512 load incomplete
  0rows DT261487
  GH/.../Everest/Customer-Cases/issues/662
  

Local fix

• If your verification has lead to the conclusion that a load task
  that ended with a return code 0 has not loaded the data
  completely, please rerun the load job. After the resolution of
  the high utilization of the accelerator's database, the load
  operation will be successful again.
  

Problem summary

• Problem Summary:
  Load operations can finish with RC 0 and a success message while
  the data loaded is not complete. See APAR Error Description for
  details. Subsequently, queries processing tables with
  incomplete data lead to incomplete (meaning wrong) results.
  
  Users Affected:
  Users of the accelerator on IBM Z with maintenance level
  7.5.12.0 performing one of the following functions:
  - Load or reload of an accelerator-shadow table (partition)
  - Full table reload
  - Load into an AOT (using the external load function of the
    Accelerator Loader)
  - Archiving of a table
  as well as users running queries which are processing tables
  that have not been loaded completely.
  
  Problem Scenario:
  See APAR Error Description.
  
  Problem Symptoms:
  See APAR Error Description.
  

Problem conclusion

• The issue has been fixed with Accelerator maintenance level
  7.5.12.1. If you are running Accelerator maintenance level
  7.5.12.0, we strongly recommend to upgrade immediately to
  7.5.12.1 or later.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels