PH38212: ABEND04E RC00C90101 AT DSNKFTBU ERQUAL5061 AND DSNK1CNE ERQUAL5006 DURING FTB CREATION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When Db2 trys to create a FTB for an index object, during the
  sanity check, if the number of entries in the FTB on a different
  member are not the same, Db2 will set an internal error code to
  indicate such error is found and produces multiple dumps within
  the Db2 group.
  
  For the member initiating the FTB creation, it abends with
  DSNKFTBU 5061  For the other members, abend at DSNK1CNE 5006 can
  be seen. The ftb high key count in dump DSNKFTBU 5061 is
  different with the numbers in dump DSNK1CNE 5006
  Therefore, the FTB creation fails.
  
  Additional keywords: DB2FTB/K
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Db2 12 for z/OS data sharing users                       *
  * with in-memory index optimization function                   *
  * enabled (Index Fast Traverse Block-FTB).                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * In a Db2 12 data sharing system, when                        *
  * index fast traverse block(FTB) is in                         *
  * use, the following ABENDs could happen                       *
  * during the index FTB creation time:                          *
  * ABEND04E RC00C90101,                                         *
  * LOC=DSNIDM.DSNKFTBU EQUAL5061                                *
  * ABEND04E RC00C90101,                                         *
  * LOC=DSNIDM.DSNK1CNE EQUAL5006                                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  Db2 requests index tree lotch before creating FTB in order to
  serialize with other operations modifying the index tree
  structure such as index page split and index page delete.
  In a data sharing system, if the index pageset is not GBP
  dependent when the index tree lotch is requested, Db2 will not
  request index tree P-lock. In a very small timing window,
  the index becomes GBP dependent while the FTB is created.
  The lack of index tree P-lock protection will cause the FTB to
  be created without using the most up to date non leaf page
  information if there is a concurrent index page split or page
  deletion running on a different Db2 member.
  If there are existing FTBs on other Db2 members with correct
  information, Db2 detects this problem at create FTB time
  by issuing ABEND04E RC00C90101, LOC=DSNIDM.DSNKFTBU EQUAL5061
  or ABEND04E RC00C90101, LOC=DSNIDM.DSNK1CNE EQUAL5006 ABENDs,
  the FTB with inconsistent information will be freed.
  Db2 could also ABEND with ABEND04E RC00C90101,
  LOC=DSNIDM.DSNKFTIN ERQUAL5002 or
  ABEND04E RC00C90101, LOC=DSNIDM.DSNKINSN ERQUAL5009 or
  ABEND04E RC00C90101, LOC=DSNIDM.DSNK1CNE ERQUAL5002
  when another Db2 member updates this FTB during index page
  split and detects an inconsistency between the FTB and the
  index non leaf page. This inconsistency could also cause
  incorrect result being returned when this index is used by
  SQL query access.
  

Problem conclusion

• Db2 code has been modified to detect the situation that an
  index becomes GBP dependent while the FTB is created. The
  FTB creation will be skipped, this will avoid the FTB to
  be built with inconsistent non leaf page information.
  Additional keywords:
  FTB, FastTraverseBlock, DB2FTB/K
  

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:

  UI76239

Modules/Macros

• DSNKFTBU
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI76239

     UP21/07/15 P F107 ¢

Fix is available

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