PH25560: PERFORMANCE DEGRADATION MAY OCCUR WITH QUERIES ON HPSS TABLES. DISTRIBUTION/ORGANIZING KEYS ARE NOT APPLIED TO ARCHIVED TABLES.

APAR status

• Closed as documentation error.

Error description

• Response times of queries involving HPSS tables may be worse
  compared with IDAA V5. To get relief customers may want to
  improve the query performance by setting organizing or
  distribution keys. Regardless whether this is attempted using
  a) Stored procedure ACCEL_ALTER_TABLES
  or
  b) Archive or Alter Keys controls in IBM Db2 Analytics
  Accelerator Studio or Data Server Manager
  the intended distribution and organizing keys are not be applied
  archived tables.
  Impact:
  Query Performance of queries using archived tables can not be
  improved by setting distribution or organizing keys.
  Additional keywords:
  HPSS, archived tables, distribution key, organizing key,
  stored procedures ACCEL_ALTER_TABLES, ACCEL_ARCHIVE_TABLES
  TS003299885 TS003471170 TS003503309 TS003666186
  

Local fix

• Contact IBM support to get the keys set manually for the
  affected archived tables using remote maintenance on the
  accelerator. This operation requires an outage.
  Since the affected table(s) must be sorted or redistributed this
  may take a few hours depending on the amount of data in the
  tables.
  

Problem summary

• The change of the distribution key or the organizing keys of an
  accelerator-archive table using
  -Db2 Analytics Accelerator Studio
  -Data Server Manager
  -ACCEL_ALTER_TABLES stored procedures
  so far has only been only possible for the active partitions,
  but not for the archived ones.
  
  The program has been enhanced to support changes of the
  distribution key or the organizing keys of both the active and
  archived partitions of an accelerator-archive. 
  The new support needs to be enabled by IBM support who will set
  the new configuration parameter
  ENABLE_ALTER_KEYS_FOR_ARCHIVE_TABLES=TRUE.
  
  
  The fix is part of maintenance level 7.5.2.
  
  
  Note: with maintenance level 7.5.3 the support will be
  activated as default.
  

Problem conclusion

• Upgrade your accelerator maintenance level to 7.5.2 or higher.
  

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