JR21097: REMOVAL OF REDUNDANT TRANSITIVE PREDICATES MIGHT CAUSE PERFORMANCE DEGRADATION FOR FEDERATED QUERIES

APAR status

• Closed as program error.

Error description

• The removal of redundant transitive predicates might cause
  performance degradation for federated queries running against
  certain data sources. The workaround is to control the removal
  of redundant predicates through a new server option,
  DB2_KEEP_TRANSITIVE_PREDS, with two possible values 'Y' and 'N'.
  If this server option is set to 'Y', all predicates will be kept
  and sent to the remote data source. Otherwise, if this server
  option is not specified or if its value is set to 'N', the
  current functionality applies and the redundant predicates are
  removed from the statement sent to the remote data source.
  This option is introduced in DB2 UDB v8.2 Fixpak 10
  

Local fix

Problem summary

• The removal of redundant transitive predicates might cause
  performance degradation for federated queries running against
  certain data sources. The workaround is to control the removal
  of redundant predicates through a new server option,
  DB2_KEEP_TRANSITIVE_PREDS, with two possible values 'Y' and 'N'.
  If this server option is set to 'Y', all predicates will be kept
  and sent to the remote data source. Otherwise, if this server
  option is not specified or if its value is set to 'N', the
  current functionality applies and the redundant predicates are
  removed from the statement sent to the remote data source.
  This option is introduced in DB2 UDB v8.2 Fixpak 10
  

Problem conclusion

• Problem was first fixed in Version 8.2 FixPak 10
  

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

  WS II REL WRPR

• Fixed component ID

  5724C7405

Applicable component levels