PH46568: UNNECESSARY OVERFLOW RECORD IS CREATED FOR PAGE LEVEL LOCKING OBJECTS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• For page level locking objects, there're cases that update could
  create overflow records even when there's enough free space in
  the page.
  
  Additional symptoms: ABEND04E 00C90105 DSNIREPR ERQUAL0C1C 0C1C
                       ABEND04E RC00C90105 DSNIREPR ERQUAL0C17
                       ABEND04E RC00C90D01 DSNOTCSO OFFSET06F46
                       00C90D01 0C17
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of Db2 13 for z/OS                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * 1.ABND04E RC00C90105 AT DSNIREPR:0C1C                        *
  * or ABND04E RC00C90105 AT DSNIREPR:0C17                       *
  * when space reuse is not optimal                              *
  * during SQL update when LOCKSIZE PAGE                         *
  * or ANY is used for a tablespace.                             *
  * 2.ABND04E RC00C90D01 AT DSNOTCSO+06F46                       *
  * when the uncommitted row containing                          *
  * LOB columns was treated as the                               *
  * committed row.                                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  1.When page-level lock is held, overflow record is created even
  when data page has enough free space to accommodate the updated
  record. Page compaction did not account for page-level locking
  when determining which space could be reused.
  2.During insert searching for the space on the page, Db2
  marked the row as committed when the page was not yet
  committed. If this row contained LOB columns, any reader
  of the LOB column could encounter ABND04E RC00C90D01 AT
  DSNOTCSO+06F46 due to AUX index mismatching.
  

Problem conclusion

• 1.Db2 has been modified to check for page-level locking to
  ensure that current page is committed and that there is
  sufficient free space on page when determining whether
  updated record can fit on current page or overflow record
  will be created.
  2. Db2 has been modified to check the page's commit status
  before marking rows as committed during insert process.
  

Temporary fix

Comments

APAR Information

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

  PH25244

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

  UI90223

Modules/Macros

• DSNIDLDU DSNIDLDS DSNIKDEF DSNIDLOD DSNIDILS DSNIREPR DSNISGRT
  DSNISMCP DSNILREP DSNISMRT DSNIDLEO
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RD10 PSY UI90223

     UP23/01/31 P F301

Fix is available

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