IT16703: DB2 MAY RETURN INCORRECT RESULTS WHEN USING STRING EQUALITY PREDICATES CONTAINING DIFFERING CODE UNITS

DB2 Version 11.1 Mod1 Fix Pack1 iFix001 for Linux, UNIX, and Windows
DB2 Version 11.1 Mod 2 Fix Pack 2 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod2 Fix Pack2 iFix001 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod2 Fix Pack2 iFix002 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 3 Fix Pack 3 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod3 Fix Pack3 iFix001 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod3 Fix Pack3 iFix002 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod4 Fix Pack4 iFix001 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• When using string equality predicates containing strings that
  have differing code units (OCTETS, CODEUNITS16, CODEUNITS32),
  DB2 may return incorrect results. Keep in mind that the default
  code units used may differ depending on the current string_units
  and nchar_mapping database configuration parameters and the
  NLS_STRING_UNITS global variable.
  
  Example (with the default string_units database config parameter
  set to SYSTEM):
  
  CREATE TABLE T1 (a CHAR(2 CODEUNITS32) NOT NULL, b CHAR(5
  CODEUNITS32) NOT NULL)
  
  INSERT INTO T1 VALUES ('12', '345')
  
  SELECT a||b FROM T1 WHERE a='12' AND a||b LIKE '%12345%'
  
  Incorrect result:
  
  1
  ----------------------------
  
    0 record(s) selected.
  

Local fix

• In the example above, either modify the string_units database
  config parameter to match the string constant's code units
  (OCTETS) with the column's (CODEUNITS32), or ensure each string
  reference in the equality expression uses the same code units by
  casting when needed:
  
  SELECT a||b FROM T1 WHERE CHAR(a)='12' AND a||b LIKE '%12345%'
  
  1
  ----------------------------
  12345
  
    1 record(s) selected.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * CODEUINTS usage                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * See Error Description. Please, install this fix.             *
  ****************************************************************
  

Problem conclusion

• See Error Description. Please, install this fix.
  

Temporary fix

Comments

APAR Information

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

  IT16651

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

Fix information

• Fixed component name

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels