PI86880: V12 : ENHANCED METADATA SELF-DESCRIPTION CAPABILITY TO MINIMIZE PROBLEMS RELATED TO SCHEMA DEFINITION CHANGES

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• V12 : Enhanced Metadata self-description capability
  to minimize problems related to schema definition changes
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All DB2 12 for z/OS users                                    *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Over the years since schema evolution was introduced,        *
  * problems have increased for customer shops that meet these   *
  * three conditions:                                            *
  * - Table spaces containing a large number of tables.          *
  * - Users making frequent schema changes to the tables.        *
  * - Users regularly use the DSN1COPY utility to move or copy   *
  * table spaces from a source Db2 subsystem to a target         *
  * subsystem.                                                   *
  * The problems fall into two broad categories:                 *
  * - Data Integrity: After a table space is copied from a       *
  * source Db2 subsystem to a target subsystem, mismatches       *
  * between the metadata in the system pages of the table space  *
  * and the information in the catalog or directory can occur.   *
  * Due to those mismatches, the data rows cannot be properly    *
  * processed. These problems are more frequent for tables in    *
  * the table space that have not been altered.                  *
  * - Version Recycling: Because there are only 255 versions     *
  * available for mapping all schema definitions for all tables  *
  * in a table space, all versions might be used, and there is   *
  * no effective way to drop and reuse old version numbers.      *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  Many of the data integrity problems are due to metadata that is
  missing from the system pages in a table space after data was
  copied from one system to the other.  This metadata includes the
  number of columns, and column types and lengths. Corresponding
  information is in the catalog and directory, but the data in the
  catalog and directory might not be matching for the current
  table definitions. If a table space contains the system pages
  for all versions of the data rows within it, Db2 does not need
  the catalog or directory for interpreting data rows. That table
  space is self-describing.
  The original implementation for schema evolution inserted a
  system page into a table space only after an INSERT, UPDATE, or
  LOAD operation that followed an ALTER statement which created a
  new definition of a table in the table space. If an ALTER was
  never executed on a table in the table space, the original table
  definitions of the tables were never captured in system pages.
  If a table without a system page was copied to another DB2
  subsystem, the catalog or directory definition might not match
  the table definition.
  

Problem conclusion

• This APAR contains enhancements to make table spaces
  self-describing. These changes apply to simple, segmented
  (non-UTS), partitioned (non-UTS), partition-by-range (absolute
  or relative addressing), and partition-by-growth table spaces.
  These enhancements do not apply to work files, XML table spaces,
  and LOB table spaces.
  
  Specific changes are:
  
  - Db2 inserts a system page with a table?s original schema
  definition into the containing page set when the table has a
  complete definition. A complete definition means that the table
  and all dependent objects are defined. The value of the STATUS
  column is not 'I' in the row for the table in SYSIBM.SYSTABLES.
  - Db2 gives newly created tables in a multi-table simple or
  segmented table space an initial version number that matches the
  current version number of the table space
  (SYSTABLESPACE.CURRENT_VERSION instead of 0).
  - When no tables in a table space have been altered, and data is
  inserted or updated in one of those tables, Db2 inserts a
  version 0 system page into the table space for that table.
  - The LOAD REPLACE and REORG utilities insert a version 0 system
  page into a table space for tables that are at version 0.
  - The COPY, LOAD, and REORG utilities place a more accurate
  version number in SYSCOPY.OLDEST_VERSION.
  - The new REPAIR utility keyword INSERTVERSIONPAGES directs
  REPAIR to insert missing version 0 system pages in the specified
  table space.
  - The new REPAIR utility keyword combination INSERTVERSIONPAGES
  SETCURRENTVERSION directs REPAIR to perform these actions:
     * Insert missing system pages for any table that has not been
  altered
     * Set the SYSTABLES.VERSION value for all tables to the
  SYSTABLESPACE.CURRENT_VERSION value for the table space.
  After REPAIR is run, REORG can be run to update data rows to the
  current version and roll up version numbers to the current
  version of the table space. These actions fix the problem that
  prevents a version-generating ALTER when the table space is at
  version 255 and a table in the table space is at version 0.
  - For a single-table table space, after data is copied with
  DSN1COPY, the REORG, COPY, RUNSTATS, REBUILD, CHECK INDEX, CHECK
  DATA, and UNLOAD utilities perform enhanced schema checking when
  the table space is physically opened. This schema checking
  performs the same functions that REPAIR CATALOG performs.
  
  See the following topics in the IBM Knowledge Center for more
  information:
  http://www.ibm.com/support/knowledgecenter/SSEPEK_12.0.0/wnew/sr
  c/tpc/db2z_minorenhancementsinapars.html ( see "Enhancements to
  address problems after Db2 for z/OS table definition changes")
  http://www.ibm.com/support/knowledgecenter/SSEPEK_12.0.0/ugref/s
  rc/tpc/db2z_repairsyntax.html
  http://www.ibm.com/support/knowledgecenter/SSEPEK_12.0.0/ugref/s
  rc/tpc/db2z_copytablessubsystem.html
  http://www.ibm.com/support/knowledgecenter/SSEPEK_12.0.0/admin/s
  rc/tpc/db2z_tablespaceversions.html
  

Temporary fix

Comments

• ×**** PE18/12/13 FIX IN ERROR. SEE APAR PH05268  FOR DESCRIPTION
  

APAR Information

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

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

  UI51746

Modules/Macros

• DSNXIALC DSNGDIE1 DSNXICTB DSNXIPGA DSNURRST DSNDQWPZ DSNUCBVR
  DSNDSPRM DSNUCBRP DSNUBINS DSNIVGET DSNIVOBD DSNGDADR DSNGDAPT
  DSNIPPHO DSNXICX2 DSNIPTYM DSNXIATB DSNGDADP DSNIPPS  DSNUBAUS
  DSNXIDCO DSNGDADB DSNXISB9 DSNUGUCA DSNISMRT DSNXISB3 DSNXISB6
  DSNIDLOD DSNXIPKY DSNURFIT DSNISRTI DSNILDVC DSNIROBD DSNPRST0
  DSNURSYC DSNUMSGD DSNUMSGC DSNUGPTC DSNGDART DSNPCPS0 DSNUGPPN
  DSNIDMPS DSNIFOD  DSNIHLOD DSNILPG  DSNGDBRT DSNGDACL DSNISCHV
  DSNURWT  DSNUGPRZ DSNFUDIR DSNUGPRV DSNUGPRT DSNGDEST DSNILREP
  DSNXICIX DSNISGRT DSNXI14  DSNXIDMN DSNUGDDN DSNIRELK DSNXIAB3
  DSNXIAB2 DSNXIAB1 DSNFUDRD DSNIETRV DSNXIAB6 DSNURWI  DSNXIAB5
  DSNFUDRC DSNXICB2 DSNXIPND DSNUBASI DSNXICB4 DSNUGRST DSN6SPRC
  DSNUGUVR
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI51746

     UP17/11/23 P F711

Fix is available

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