IT27081: SAP: SUBOPTIMAL PERFORMANCE FOR QUERIES WITH INEQUALITY PREDICATES ON COLUMNIZED TABLES

Db2 Version 11.1 Mod4 Fix Pack4 iFix001 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 5 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 7 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• Suboptimal performance can be observe when running a query with
  the following characteristics:
  
  1. the query runs on columnized tables
  2. the query contains an equality predicate and an inequality
  predicate
  3. the inequality predicate can be rewritten to containing only
  constants and host variables based on the equality predicate
  
  An example query:
  select 1 from col_table where c1<>9 and c1=:HV
  

Local fix

• manually rewrite the inequality predicate. The example query can
  be rewritten to:
  select 1 from col_table, (select * from values(0) where :HV<>9)
  where c1=:HV
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher                *
  ****************************************************************
  

Problem conclusion

• First fixed in Db2 11.1 Mod 4 Fixpack 5
  

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

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels

• RB10 PSN

     UP