PH24667: ABEND04E 00C90101 LOC DSNIDM DSNKDPG ERQUAL 500A OCCURRED DURING INDEX PAGE DELETION FOR FTB

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• ABEND04E RC00C90101 LOC=DSNIDM.DSNKDPG ERQUAL500A
  occurred during index page deletion when index fast
  traverse block(FTB) is in use.
  Additional Symptoms: ABEND 04E 00C90101 DSNKINSN ERQUAL 5009
                       DSNKFEXT 5001 5002 DSNKFLOK 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, ABEND04E RC00C90101,LOC=DSNIDM.                         *
  * DSNKDPG ERQUAL500A occurred during                           *
  * index page deletion.                                         *
  * ABEND04E RC00C90101,LOC=DSNIDM.                              *
  * DSNKINSN ERQUAL5009 occurred                                 *
  * during index page split.                                     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  In a Db2 12 data sharing system, when FTB is in use, the Db2
  member running SQL INSERT or SQL DELETE needs to use FTB
  physical lock (P-lock) to send notify messages to other Db2
  members to update their FTB information when an index page
  split or deletion happens.
  The following problems exist in the FTB P-lock area:
  1> If the FTB P-lock status maintained on each
  Db2 member has inconsistent state, the notify message will
  not work properly and FTB information can become inconsistent
  with the index non leaf page information, thus causing
  ABEND04E RC00C90101,LOC=DSNIDM.DSNKINSN ERQUAL5009 or
  ABEND04E RC00C90101,LOC=DSNIDM.DSNKDPG ERQUAL500A
  during index page split or page deletion. SQL query can
  return incorrect output when the index is used for
  query access.
  2> In a small timing window, the FTB P-lock request and FTB
  P-lock exit returning out of order can cause the saved FTB
  P-lock token to have a zero value. The zero
  P-lock token will cause the ABEND04E RC00C90101,LOC=DSNIDM.
  DSNKDPG ERQUAL500A or ABEND04E RC00C90101,LOC=DSNIDM.
  DSNKINSN ERQUAL5009 when it is used to send notify messages
  to other Db2 members during index page deletion or page split.
  3> ABEND04E RC00C90101,LOC=DSNIDM.DSNKFLOK ERQUAL5002 or
  ABEND04E RC00C90101,LOC=DSNIDM.DSNKFEXT ERQUAL5001 or
  ABEND04E RC00C90101,LOC=DSNIDM.DSNKFEXT ERQUAL5002 can be
  issued when Index FTB P-lock request or FTB P-lock exit
  detects an error, Db2 doesn't setup the proper program
  recovery routine (PRR) before issuing these ABENDs,
  which causes the Db2 system crash.
  4> The FTB Intent Share (IS) P-lock can be released when an
  index page set is converted to read only mode or become non
  group buffer pool (GBP) dependent.
  In a small timing window, if the FTB is created
  while the IS P-lock is released, the FTB can be created
  without holding the proper P-lock.
  

Problem conclusion

• Db2 code has been updated in the FTB P-lock area to provide
  the following fixes:
  1> After the FTB is created for an index, the Db2 member
  which creates the FTB will send the notify
  messages to other Db2 members to verify their FTB P-lock
  state. When an invalid FTB P-lock state is detected,
  ABEND04E RC00C90101 LOC=DSNIDM.DSNK1CNE ERQUAL5005  and
  ABEND04E RC00C90101 LOC=DSNIDM.DSNKFTBU ERQUAL5061 will
  be issued and the newly created FTB will be freed. This will
  prevent the data integrity issue caused by the inconsistent
  FTB P-lock.
  2> When the FTB P-lock request and P-lock exit return out of
  order, the FTB P-lock token will be saved with a valid non zero
  value.
  3> FTB P-lock request and P-lock exit are changed to setup
  the proper program recovery routine to avoid Db2 crash when
  an ABEND is issued. The non zero return code will be
  returned from the P-lock exit so the P-lock requester can
  detect the error and fail the P-lock request. IRLM APAR PH25240
  also needs to be installed to provide this fix.
  4> FTB IS P-lock will not be released when an index page set
  is converted to read only mode or become non GBP dependent.
  

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:

  UI69831

Modules/Macros

• DSNKISPL DSNKULTH DSNKFQPL DSNKUNR2 DSNK1CNE DSNKDPG  DSNKFEXT
  DSNB1CPL DSNKFTBU DSNKFLOK DSNKINSN DSNKMDEL
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI69831

     UP20/06/11 P F006 ¢

Fix is available

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