IT34049: NEW BCD DIVISION IMPLEMENTATION FOR ROW BASED DECIMAL

Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows

APAR status

• Closed as fixed if next.

Error description

• Starting with v11.1m1fp2 the BCD DECIMAL division algorithm got
  replaced on AIX by an implementation based on decimal floating
  point instructions available on Power6 and above.
  This has made the row based DECIMAL division much faster. As a
  side effect users might experience an increased accuracy.
  
  This change now introduces a new and faster BCD DECIMAL division
  implementation for the other platforms that provides increased
  accuracy for the other platforms.
  
  Without the change on non-AIX
  
  db2
  "values(Decimal('9056550.000',19,3)/Decimal('20125666.660',19,3)
  )"
  
  will return 0.450000000000 while the expected result is
  0.450000000149.
  
  In most cases this tiny difference does not play a role as the
  result typically gets written back to DECIMAL(19,3) and then the
  difference in the last digits get truncated.
  
  To return to the old DECIMAL division implementation, use:
  
  db2set DB2_RUNTIME_DEBUG_FLAGS=DECIMAL_DIVIDE_COMPAT
  

Local fix

• Perform division using DECFLOAT data type.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * non-AIX or <= Db2 v11.1 m1fp2 or not Power6                  *
  * row based division with large scale                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to next fixpack.                                     *
  ****************************************************************
  

Problem conclusion

Temporary fix

Comments

APAR Information

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

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

Fix information

Applicable component levels

• RB10 PSN

     UP

• RB10 PSY

     UP