Properties of a Table Log Record Synonym

In this section:

The Table Log Records synonym is the synonym for a log table. These first three columns in this synonym are added automatically and used for DataMigrator IUD processing. The columns have the following functions:

The Configuration section of the CDC synonym consists of special parameters, which properties could be customized by a user. Each CDC parameter in the configuration section of the CDC synonym has a default value of a global variable whose name begins with &&CDC_ and is followed by the parameter name.

The following options are available:

DB Log Parameters

This is set to DBMSLOG to indicate the origin of the data is a DBMS table log.


Indicates the starting point for reading log records.

  • CHKPT. After the last transaction retained in checkpoint file. This is the default.
  • CUR_TRAN. The first transaction in the DBMS log after the job started.
  • CUR_LOG. The first available transaction in the current active DBMS log.

Indicates if the last processed transaction should be saved in the checkpoint file.

  • YES. Retains the last processed transaction in the checkpoint file.
  • NO. Does not retain the last processed transaction. This option facilitates testing, because use of Sample Data or Test Transforms does not reset the checkpoint.

Indicates the location and name of the file to use to store checkpoint information in a:

  • Physical location. The full directory and file name in the format for the operating system used. This option should be used when there are multiple flows that will access the log for the same table. Each flow should have a unique synonym with a unique name for the checkpoint file.
  • Application directory. The file is created in the same application directory as the synonym.
  • Blank. This is the default. If no file name is specified, a file is created with the same name as the synonym and the extension chp.

Listening Parameters

Indicates the polling interval in seconds, or how often the database log is scanned. The default is 1 second.


Indicates the timeout interval in seconds. If there is no activity in this time interval, the processing will stop. A value of zero means there is no limit. The default value is 1 second.

Note that the two options above work together. For example, if POLLING is 2 and TIMEOUT is 10, the server polls the log every 2 seconds for new transactions. If there are no new transactions after 10 seconds, then polling stops.

Read Limits

Indicates the maximum number of database transactions to process before stopping the job. A value of zero (0) means all transactions. The default value is 1 transaction.

Considerations for Table Log Records Synonyms
Timestamp parameter

The Timestamp value of the CDC parameter START is available for DB2 synonyms only.


The CUR_LOG value of the CDC parameter START is not supported by IBM DB2 on Mainframe (IBM System z).

Additional iSeries parameters

The following three parameters, COMMIT_MODE, LOG_NAME, and LOG_LOCATION are available on iSeries platforms only, with the DB2 database.

The LOG_NAME and LOG_LOCATION parameters can be used when you are required to use a non-standard journal and/or a non-current location. An example would be an alternate library, where the journal and location are explicitly manually defined by a database administrator (versus a CREATE COLLECTION). Another example would be a requirement to use a remote journal, instead of the local one.


Supports the transactional commitment control.

  • ON. Normal transaction mode with a commit used. This is the default.
  • OFF. No commit issued or DBMS uses auto-commit mode.
  • DTC. Distributed transactions mode is used.

Indicates the name of the journal.


Indicates the location name.

Current library on iSeries

When using CDC on iSeries, consider changing current library.


Start the DataMigrator server and the Data Management Console. From a user ID that is a member of the Server Administrator role, expand the Workspace folder. Then, expand the Configuration/Monitor and Configuration Files folders. Double-click Server Profile to open edasprof.prf. Look for a line that resembles the following:


Ensure that the parameter, in this example LIBRARY1, is the name of your collection. If you made a change to file, click the Save icon to save the changes.

Checkpoint file on z/OS

On a mainframe the checkpoint file should be created first. This can be done by creating two focexec procedures and running them simultaneously: one procedure to report against a Table Log Records synonym and the other procedure will issue an update against the underlying actual table. For more information, see Creating a Checkpoint File on z/OS.

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