Data Replication stores a Sync Point value in the configuration for each of the mapped target tables. This value indicates the point up to which InitialSync synchronized the target tables with the source tables.
Initially, a configuration specifies -1 as the Sync Point value for all of the mapped tables. This value indicates that initial synchronization has not been completed for the target tables.
When you run InitialSync, it synchronizes the mapped target tables with the source tables for which the Sync Point value is -1. Data Replication then writes an updated Sync Point value to the configuration for each synchronized table, as follows:
For Oracle
and Microsoft SQL Server
sources, InitialSync retrieves the system change number (SCN)
or log sequence number (LSN)
value from the source database for the initial synchronization transaction and writes this value to the configuration for each synchronized table.
For MySQL sources, InitialSync retrieves the log coordinates from the source database for the initial synchronization. InitialSync writes this value to the configuration for each synchronized table.
For DB2 for Linux, UNIX, and Windows sources, InitialSync adds records to the service table, which is named DBSYNC_SYNC_LSN by default, for each synchronized table. When you run the Extractor later, it uses these records to determine the LSN value of the source database up to which the target tables are synchronized with the source tables. The Extractor writes this value to the configuration for each synchronized table.
In the Data Replication Console, you can manually edit the Sync Point value that is stored in a configuration for a mapped table. You might need to edit the Sync Point value for a particular table under the following circumstances:
You need to resynchronize a target table that was previously synchronized. For example, InitialSync ended abnormally. In this case, you need to truncate the table, set its Sync Point value to -1, and then run InitialSync again.
You want to skip the InitialSync task and configure the Applier to start change data replication for a table from a specific point in the logs. For example, if you use a third-party utility to synchronize target tables, you can set the Sync Point value to the SCN
, log coordinates,
or LSN that corresponds to the point from which you want to start change data replication.