Db2 for i CDC Connector rules and guidelines

• •You can use Db2 for i CDC connections for sources only. Do not select this connection type for a target.
• •You must configure remote logging of Db2 for i change records to a PowerExchange Logger for LUW instance. For more information, see the PowerExchange CDC Guide for Linux, UNIX, and Windows.
• •Db2 for i CDC Connector connects to the PowerExchange Listener on the PowerExchange Logger for Linux, UNIX, and Windows (LUW) system by using the Listener Location property that you specify in the Db2 for i CDC connection definition. On the Connector system, you do not need to create a local copy of the DBMOVER configuration file that contains a NODE statement pointing to the PowerExchange Listener.
• •If you upgrade your system to a later PowerExchange version, you must stop the Secure Agent that connects to the older PowerExchange Listener before you try to connect to the upgraded PowerExchange Listener. After you edit the connection properties to specify the upgraded PowerExchange Listener, restart the Secure Agent before you try to establish the connection again. For more information, see Upgrading to a new version of PowerExchange.
• •PowerExchange does not capture change data from Db2 for i columns that have the following data types:
• - BLOB, CLOB, or DBCLOB
• - DATALINK
• - DECFLOAT
• - DISTINCT
• - ROWID
Columns that have these data types will not be included in the change records that Db2 for i CDC Connector retrieves from PowerExchange.
• •The PowerExchange Listener on the IBM i system can compress or encrypt the change data that it sends to the PWX CDC Reader component of Db2 for i CDC Connector, depending on how you set the Compression and Encryption properties for the source CDC connection.
• •Db2 for i CDC Connector supports PowerExchange Logger for LUW group definition files. A group definition file creates a separate set of PowerExchange Logger log files for each defined group of registered Db2 source tables. When a mapping task runs, the PWX CDC Reader reads only the subset of log files for the group that contains the source table.
• •If you include multiple Db2 source tables in a mapping, the PWX CDC Reader automatically uses group source processing to read change records for all of the tables in a single pass.
• •In PowerExchange, you can create capture registrations only for Db2 for i source tables that are associated with physical files. PowerExchange reads change data for the registered source tables from the Db2 journal receivers. For more information about CDC considerations and limitations, see the PowerExchange CDC Guide for i5/OS.
• •The PWX CDC Metadata Adapter retrieves information for registered Db2 for i source tables from the PowerExchange extraction-map data set, DTLCAMAP, on the Db2 for i source system, provided that you specify the Map Location, Map User, and Map Password properties for the source connection. The Adapter retrieves information only from PowerExchange-generated extraction maps that have names beginning with "d." The extraction maps provide information, such as the incoming fields, that will be used when you create a mapping. The Adapter does not retrieve information from user-defined extraction maps that have names beginning with "u" for un-defined.
• • The PowerExchange change data extraction modes, as defined in the PowerExchange CDC Guide for i5/OS, do not pertain to the Db2 for i CDC Connector. The PWX CDC Reader component of Db2 for i CDC Connector extracts change records until it reaches the end-of-log in the PowerExchange Logger log files and then stops. However, the PowerExchange configuration that the PWX CDC Reader requires is similar to the configuration for continuous extraction mode in the following ways:
• - A CAPX CAPI_CONNECTION statement must exist in the PowerExchange DBMOVER configuration file on the PowerExchange Logger for Linux, UNIX, and Windows system.
• - The capture registrations for Db2 source tables must specify Part for the Condense option.
• • The maximum network buffer size that the PowerExchange Listener can use for sending data is 8 MB. If you have a mapping with an extremely large Db2 source table, this maximum buffer size might be exceeded. In this case, the mapping task fails with the following error:
PWXPC_10034 [date time] [ERROR] CDCDispatcher cannot fetch changed data from the PowerExchange Listener. Error code: [271]
• •If you change the source object in a mapping that has been used for CDC processing, create a new mapping task for the mapping. If you need to retain the mapping task that is currently associated with the mapping, increment the revision number in the CDC Runtime properties for the mapping task.