PM82500: ABEND04E RC00C90101 IN DSNIZLDR:5004 ON RUNSTATS TABLESAMPLE SYSTEM OF A COMPRESSED PARTITIONED TABLESPACE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• RUNSTATS TABLESAMPLE SYSTEM on a partitioned tablespace might
  get abend04e rc00c90101 in DSNIZLDR:5004 when reading a
  compressed partition of a partitioned tablespace and it is not
  using the correct compression dictionary of the partition to
  decode the row being read.
  Analysis of the dump showed that in this case, when reading
  partition 2 it was pointing to partition 1 which did not have
  a compression dictionary (first partition was empty).
  In cases when the 1st partition is empty but does have a
  compression dictionary an abend0C7 in DSNUSTBL.
  .
  other possible symptoms:
  ABEND04E RC00E20005 DSNUGSTA.DSNSVBK +1AB6
  ABEND0C4-00000038, DSNIDM  .DSNIMOFR+02D8
  DB2OVRLAY/K
  

Local fix

• Until the fix is applied, running with TABLESAMPLE SYSTEM 100
  or omitting the TABLESAMPLE option will bypass the problem.
  
  02/21/2013: Internal note: AM82500 $HDBAA10 on DOC FIX disk.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 10 for z/OS (NFM) users of RUNSTATS  *
  *                 with TABLESAMPLE SYSTEM option against a     *
  *                 compressed partitioned table space (classic  *
  *                 or universal) whose partition 1 is empty     *
  ****************************************************************
  * PROBLEM DESCRIPTION: During RUNSTATS with TABLESAMPLE SYSTEM *
  *                      running on compressed partitioned table *
  *                      space (classic or universal) whose      *
  *                      partition 1 is empty, the following     *
  *                      symptoms can occur:                     *
  *                                                              *
  *                      ABEND04E RC00C90101 DSNIZLDR ERQUAL5004 *
  *                                                              *
  *                      ABEND0C7 DSNIRFNX+B49A with MSGDSNU017I *
  *                      REASON=X'00C7' in the RUNSTATS joblog   *
  *                                                              *
  *                      ABEND0C7 DSNUSTBL+657E with MSGDSNU017I *
  *                      RC00E40347 in the RUNSTATS joblog       *
  *                                                              *
  *                      ABEND0C4 DSNIMOFR+02D8 with overlay,    *
  *                      followed by ABEND04E RC00E20005 during  *
  *                      thread deallocation                     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  While running RUNSTATS with TABLESAMPLE SYSTEM (where the
  sampling value is not 100) on a compressed partitioned table
  space (classic or universal) whose partition 1 is empty, the
  aforementioned abends could occur during row decompression stage
  of the RUNSTATS page sampling scan.
  
  In the 04E DSNIZLDR:5004 case, DB2 attempted to decompress a
  row from partition 2 using partition 1's compression dictionary,
  which did not exist.
  
  In the 0C7 DSNIRFNX+B49A and 0C7 DSNUSTBL+657E cases, DB2
  attempted to decompress a row from partition 2 using
  partition 1's compression dictionary, which existed from the
  time when partition 1 had some data. However, the dictionary did
  not match this partition 2 row, hence the abend.
  
  In the 0C4 DSNIMOFR+02D8 case (followed by 04E RC00E20005
  DSNUGSTA.DSNSVBK+1AB6 during thread deallocation), the abends
  occurred because the internal MSIB and USBL structures were
  overlaid given that DB2 tried to decompress a row from partition
  2 using partition 1's compression dictionary. Due to the
  incorrect dictionary used as well as row conversion to the
  latest OBD format, the row was now bigger than the maximum
  possible row size for the table, exceeding into surrounding
  memory areas used by MSIB and USBL. Other, unpredictable memory
  areas can theoretically be overlaid also.
  
  The root cause of the abends is that the TABLESAMPLE code set an
  internal partition indicator to 1, incorrectly assuming that
  partition 1 would always participate in page sampling. However,
  this was not the case when partition 1 was empty.
  

Problem conclusion

• Code has been changed to ensure that the internal partition
  indicator always reflects the partition covering the pages
  being sampled.
  
  Additional keywords: ABENDS0C7 OFFSETB49A OFFSET657E OFFSET02D8
                       SMCOVERLAY DB2OVRLAY/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:

  UK93661

Modules/Macros

• DSNIPGSP
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK93661

     UP13/05/07 P F305

Fix is available

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