PM24721: BIND PERFORMANCE IMPROVEMENT ON LOB TABLE SPACE.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• BIND performance improvement on LOB table space.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: 1. All DB2 for z/OS users who needs to bind  *
  *                    or rebind applications.                   *
  *                 2. All DB2 for z/OS users who use RTS table  *
  *                                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: 1. The LOB table spaces of catalog and  *
  *                         directory Objects could show high    *
  *                         getpage activity and grow rapidly    *
  *                         during application BIND/REBIND       *
  *                         process.                             *
  *                      2. The NPAGE value of LOB table space   *
  *                         is not updated in the RTS table.     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  *                                                              *
  ****************************************************************
  1. The LOB table spaces of catalog and directory objects could
   show high getpage activity and grow rapidly during application
   BIND/REBIND process. This is because the REBIND process
   deletes the old package and insert a new package.
   The deleted space is not reused until the REBIND job is
   committed. During the space search, DB2 analyses these pages
   each time a LOB is inserted, resulting in increased getpage
   activity that could trigger the insert algorithm to insert at
   the end and skipping available free space.
   Therefore, the LOB table space could grow rapidly if many
   REBIND package statements are run in parallel.
  
  2. The in-memory NPAGE value of RTS control block is not
     updated during the DML operation of LOB data.
  

Problem conclusion

• 1. The space search algorithm has been changed to cache the
     lowest space map page from the last inserted record
     if the object is DBD01 or DBD06.
     Any subsequence insert will search the data from the cached
     space map page until the prior deleted space is committed.
     This process can avoid searching the uncommitted delete
     space created by BIND/REBIND process repeatedly and further
     reduce getpage activity and CPU time, and is less likely to
     trigger insert at end, hereby reducing the space growth.
     Once the deleted space is committed, the space search
     algorithm is resumed to its original process for any
     subsequence insert.
     Thereafter, the same process is repeated and a new cached
     space map page will be established.
  
  2. The logic has been changed to update NPAGE value of RTS
     in-memory control block during operation of LOB data.
  

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:

  UK63457

Modules/Macros

• B390SPA1 B390SPA2
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK63457

     UP11/01/11 P F101

Fix is available

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