IC95034: OPTIMIZER PROCESSES QUERY IN DIFFERENT ORDER THAN ON V10 WHICH SIGNIFICANTLY IMPACTS EXECUTION TIME

APAR status

• Closed as program error.

Error description

• You have done migration or upgrade from v10 to v11.50 and above
  and you noticed that certain multi-table queries are being
  executed slower than on Informix v10. You have inspected the
  query plans and noticed that on new version of Informix the
  optimizer is processing tables in the order different than on
  v10. For example:
  
  v10: tab1 -> tab2 -> join..
  v11.50 and above: tab2 -> tab1 -> join...
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All 11.70 and 12.10 users.                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * A query may have suboptimal query plan under the following   *
  * conditions:                                                  *
  *  - a correlated subquery exists                              *
  *  - a cartesian join is performed between 2 tables            *
  *  - one of the tables involved in cartesian join is           *
  * performing an index scan with table filters                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IDS-11.70.xC8                                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IDS-11.70.xC8
  

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

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels

• RB70 PSN

     UP

• RC10 PSN

     UP