PI11661: LOB INSERT PERFORMANCE DEGRADATION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Performance degradation in LOB inserts from space search
  due to an old LRSN.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: DB2 data sharing users.                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: INSERT performance degradation, and/or  *
  *                      poor space reuse, particularly for LOBs *
  *                      but possibly for other tables as well.  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The value of the global read-LSN limits DB2's ability to reuse
  deleted space for LOBs, as well as for:
    - Tables using static scrollable cursors.
    - Tables sharing a buffer pool with LOBs or tables using
      static scrollable cursors.
  
  DB2 may fail to advance the global read-LSN values for long
  periods of time if LOB read claims and/or static scrollable
  cursors are continuously coming and going, such that there are
  few points in time where no read interest is registered at all.
  This failure to advance the global read-LSN happens even though
  the local table-level and buffer pool values are moving forward.
  

Problem conclusion

• The code which handles the advancement of the global read-LSN
  has been modified to detect when the global value is lagging
  behind the local value, and to try to advance it in that case.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UI16789 UI16790 UI16791

Modules/Macros

• DSNB1PCK
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UI16789

     UP14/04/23 P F404 ¢

• RB10 PSY UI16790

     UP14/04/23 P F404 ¢

• R910 PSY UI16791

     UP14/04/23 P F404 ¢

Fix is available

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