PH64099: NEW FUNCTION FOR IFI306 USERS ON COMPRESSED TABLESPACES

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• New Function for IFI306 users to retrieve log records on
  compressed tablespaces
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Db2 13 for z/OS users who use            *
  *                 applications that utilize IFI READS          *
  *                 calls for IFCID 0306 to retrieve             *
  *                 log records for compressed table spaces,     *
  *                 excluding those who use the GDPS             *
  *                 Continuous Availability solution.            *
  ****************************************************************
  * PROBLEM DESCRIPTION: Reading log records for a compressed    *
  *                      table space using IFI READS calls for   *
  *                      IFCID 0306 requires access to the       *
  *                      expansion dictionary associated with    *
  *                      the table space. Performance            *
  *                      degradation and serialization issues    *
  *                      may occur when accessing the            *
  *                      expansion dictionary within the         *
  *                      compressed table space or retrieving    *
  *                      it from a log data set, especially      *
  *                      when it's an archive log on tape        *
  ****************************************************************
  For compressed data, IFCID 0306 processing requires
  access to the associated expansion dictionary
  to decompress the contents of a log record before returning
  the log record to the IFI callers.
  Users of replication applications require a method to access
  the contents of the expansion dictionary for a compressed
  pageset without needing to open it or retrieve log records.
  

Problem conclusion

Temporary fix

Comments

• This new function can be used in both data sharing and
  non-data sharing systems on Db2 13 function level 500 or
  higher.
  
  This APAR introduces the capability for users to store
  expansion dictionaries in the Compression Dictionary
  Data Set (CDDS). It enables IFCID 0306 application users
  to utilize the expansion dictionaries stored in the CDDS
  to decompress log records. This new functionality does not
  affect users who have already been using the CDDS for
  the GDPS Continuous Availability solution.
  
  Using the expansion dictionaries stored in the CDDS
  to decompress log records can offer the following advantages:
    - Compressed table spaces referenced in retrieved log
      records do not need to be opened to access the
      expansion dictionary for decompression.
    - Db2 avoids the need to obtain a DBD lock or
      claim on the referenced table spaces.
    - Db2 no longer requires access to expansion dictionaries
      from the logs.
  
  Users of IFCID 0306 applications should refer to
  the respective documentation to determine whether this
  Db2 feature is supported and whether any changes are
  necessary.
  
  Users using Q Replication for InfoSphere Data
  Replication (IIDR) should have APAR PH64273 applied.
  
  Do NOT set the subsystem parameter CDDS_MODE to SOURCE_ONLY
  unless you plan to use this new function.
  
  For more information on using the expansion dictionaries
  stored in the CDDS to decompress log records, refer to the
  online product documentation and search using the following
  keywords:
  - PH64099
  - QWHS0306,QW0306
  - Reading complete log data (IFCID 0306)
  - Storing the expansion dictionary for compressed log
    records in the CDDS
  

APAR Information

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

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

  UO02927

Modules/Macros

• DSN6LOGP DSNDQW04 DSNDQWPZ DSNIDALC DSNIDCML DSNIDCPN DSNIDCSF
  DSNIDCST DSNIDCVL DSNIDLGR DSNIERST DSNIIEPL DSNILGRT DSNILGRX
  DSNIQGSE DSNLJMLR DSNURPDC DSNWARDS DSNWZIFD DSNZOVTB
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RD10 PSY UO02927

     UP25/05/13 I 1000  

Fix is available

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