Changes to registry and environment variables in Db2 11.5

To support new and changed functionality in Db2 version 11.5, a number of changes were made to registry and environment variables.

Review the changes to learn which ones might affect your existing applications and to determine whether you have to adjust them.

Also, review the list of deprecated and discontinued registry variables to learn about additional changes that might also affect your applications and scripts.


Changed behaviors
The following table describes the changes to registry variables in version 11.5:
Table 1. Registry variables with changed behaviors
Registry variable Changed behavior
DB2_INDEX_CREATE_ALLOW_WRITE In pureScale environments, the default behavior is now ON, applications are allowed write access to the table during index creation by default
DB2_ENABLE_PS_EXTENT_RECLAIM In pureScale environments, the default behavior is now ON, reclaimable storage operations are allowed in Db2 pureScale environments by default.
DB2_USE_BUFFERED_READ_FOR_ACTIVE_LOG The default value has changed from OFF to ON.
DB2_USE_ASYNC_FOR_MIRRORLOG The default value has changed from OFF to ON.
DB2_HADR_ROS_AVOID_REPLAY_ONLY_WINDOW The default value has changed from OFF to ON.
DB2_EXTEND_COL_UNIQUE_INDEX_ACCESS The default value has changed from OFF to ON.
Discontinued variables
The following registry and environment variables have been discontinued since version 10.5. You should remove all references to DB2_INDEX_FREE and DB2_TRUSTED_BINDIN in version 11.5:
Table 2. Registry variables that are discontinued
Registry variable Details
DB2_INDEX_FREE This registry variable provided the same functionality as the PCTFREE clause in a CREATE INDEX statement. The difference is that DB2_INDEX_FREE applies to all indexes that you create and the PCTFREE clause applies to one index. For more details, see CREATE INDEX statement. Setting this registry variable results in an error because the associated functionality is no longer available.
DB2_TRUSTED_BINDIN This variable is discontinued because it is no longer supported for improving the performance of query statements containing host variables within an embedded unfenced stored procedure.


Take advantage of enhanced functionality or new features by using new registry variables or new values for registry variables.

For new registry variables or changes to registry variables that result in Db2 server behavior changes, adjust your applications or scripts.

Remove the use of registry variables that are discontinued as they do not have the intended effect. If a replacement registry variable is indicated in Table 2, set it to the proper value to maintain wanted database manager behavior.

For more information on deprecated or discontinued behavior in version 11.5, see Summary of deprecated and discontinued Db2 functionality in version 11.5 and earlier releases.