Partitioned database environment variables

You use partitioned database environment variables to control the default behavior of a partitioned database environment, including authorization, failover, and network behavior.

DB2_ASYNC_DPF_INDOUBT_RESOLUTION
  • Operating system: All
  • Default=ON, Values: ON or OFF
  • When set to OFF, Db2® will make one attempt to resolve each indoubt transaction as part of crash recovery. If the indoubt transactions are not resolved, no further attempt will be made by Db2 until the next database restart. When set to ON, Db2 will continue to attempt to resolve indoubt transactions asynchronously until all are resolved.
DB2CHGPWD_EEE
  • Operating system: Db2 ESE on AIX®, Linux®, and Windows
  • Default=NULL, Values: YES or NO
  • This variable specifies whether you allow other users to change passwords on AIX or Windows ESE systems. You must ensure that the passwords for all database partitions or nodes are maintained centrally using either a Windows domain controller on Windows, or LDAP on AIX. If not maintained centrally, passwords may not be consistent across all database partitions or nodes. This could result in a password being changed only at the database partition to which the user connects to make the change.
DB2_FCM_SETTINGS
  • Operating system: Linux
  • Default=YES, Values:
    • FCM_MAXIMIZE_SET_SIZE:[YES|TRUE|NO|FALSE]. The default value for FCM_MAXIMIZE_SET_SIZE is YES.
    • FCM_CFG_BASE_AS_FLOOR: [YES|TRUE|NO|FALSE]. The default value for FCM_CFG_BASE_AS_FLOOR is NO.
  • You can set the DB2_FCM_SETTINGS registry variable with the FCM_MAXIMIZE_SET_SIZE token to preallocate a default 4 GB of space for the fast communication manager (FCM) buffer. The token must have a value of either YES or TRUE to enable this feature.

    You can use the DB2_FCM_SETTINGS registry variable with the FCM_CFG_BASE_AS_FLOOR option to set the base value as the floor for the fcm_num_buffers and fcm_num_channels database manager configuration parameters. When the FCM_CFG_BASE_AS_FLOOR option is set to YES or TRUE, and these parameters are set to AUTOMATIC and have an initial or starting value, Db2 will not tune them below this value.

DB2_FORCE_OFFLINE_ADD_PARTITION
  • Operating system: All
  • Default=FALSE, Values: FALSE or TRUE
  • This variable allows you to specify that add database partition server operations are to be performed offline. The default setting of FALSE indicates that Db2 database partition servers can be added without taking the database offline. However, if you want the operation to be performed offline or if some limitation prevents you from adding database partition servers when the database is online, set DB2_FORCE_OFFLINE_ADD_PARTITION to TRUE. When this variable is set to TRUE, new Db2 database partition servers are added according to the Version 9.5 and earlier versions' behavior; that is, new database partition servers are not visible to the instance until it has been shut down and restarted.
DB2_NUM_FAILOVER_NODES
  • Operating system: All
  • Default=2, Values: 0 to the required number of database partitions
  • Set DB2_NUM_FAILOVER_NODES to specify the number of additional database partitions that might need to be started on a machine in the event of failover.

    In a Db2 database high availability solution, if a database server fails, the database partitions on the failed machine can be restarted on another machine. The fast communication manager (FCM) uses DB2_NUM_FAILOVER_NODES to calculate how much memory to reserve on each machine to facilitate this failover.

    For example, consider the following configuration:
    • Machine A has two database partitions: 1 and 2.
    • Machine B has two database partitions: 3 and 4.
    • DB2_NUM_FAILOVER_NODES is set to 2 on both A and B.
    At START DBM, FCM will reserve enough memory on both A and B to manage up to four database partitions so that if one machine fails, the two database partitions on the failed machine can be restarted on the other machine. If machine A fails, database partitions 1 and 2 can be restarted on machine B. If machine B fails, database partitions 3 and 4 can be restarted on machine A.
DB2_PARTITIONEDLOAD_DEFAULT
  • Operating system: All supported ESE platforms
  • Default=YES, Values: YES or NO
  • The DB2_PARTITIONEDLOAD_DEFAULT registry variable lets users change the default behavior of the load utility in an ESE environment when no ESE-specific load options are specified. The default value is YES, which specifies that in an ESE environment if you do not specify ESE-specific load options, loading is attempted on all database partitions on which the target table is defined. When the value is NO, loading is attempted only on the database partition to which the load utility is currently connected.
    Note: This variable is deprecated and may be removed in a later release. The LOAD command has various options that can be used to achieve the same behavior. You can achieve the same results as the NO setting for this variable by specifying the following with the LOAD command: PARTITIONED DB CONFIG MODE LOAD_ONLY OUTPUT_DBPARTNUMS x, where x is the partition number of the partition into which you want to load data.
DB2PORTRANGE
  • Operating system: Windows
  • Values: nnnn:nnnn
  • This value is set to the TCP/IP port range used by FCM so that any additional database partitions created on another machine will also have the same port range.
DB2_DEFAULT_TABLE_DISTRIBUTION
  • Operating system: All
  • Default=NULL
  • Values: RANDOM - If explicit DISTRIBUTE BY clause is missing from CREATE TABLE statement, create table as DISTRIBUTE BY RANDOM. Setting is silently ignored for tables that can't be created as DISTRIBUTE BY RANDOM.