IC70817: MAJOR PERFORMANCE PROBLEM IN 11.50 WHEN USING NCHAR/NVARCHAR

APAR status

• Closed as program error.

Error description

• The performance for using NCHAR/NVARCHAR columns in indices,
  sort operations or filters is significantly worse in 11.50
  compared to 11.10.
  
  The following table lists the execution times for
  DB_LOCALE=de_de.1252 and a table with 200000 rows:
  
  Version                11.50                   11.10
  Data type        varchar   nvarchar      varchar   nvarchar
  
  create index     0m0.365s  1m56.599s     0m0.573s  0m1.039s
  
  select distinct  0m0.284s  0m30.543s     0m0.271s  0m0.361s
  
  select where     0m0.352s  0m3.106s      0m0.238s  0m0.296s
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users                                                    *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Operations on NCHAR and NVARCHAR columns were taking more    *
  * time than the same operations performed on CHAR and VARCHAR  *
  * columns. A large amount of processing overhead was incurred  *
  * involving collating sequences present in certain locales     *
  * such as de_DE.                                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to IDS 11.50.xC8.                                    *
  ****************************************************************
  

Problem conclusion

• A large amount of processing overhead was removed from
  collation-processing functions in IDS 11.50.xC8, thereby
  reducing the amount of execution time needed on NCHAR and
  NVARCHAR columns.
  

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

• Fixed component name

  IBM IDS ENTRP E

• Fixed component ID

  5724L2304

Applicable component levels

• RB15 PSY

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