Considerations when replicating MBCS character data

When mapping source columns to target columns that contain MBCS character data, you should take the following issues into consideration:

  • Most databases enforce NCHAR and NVARCHAR as Unicode and the encoding is not changeable.
  • All binary data types such as BLOB will not have a default encoding, although CDC Replication allows you to specify an encoding.
  • Ensure that the target column you want to send data to is large enough to store the replicated character data.
  • Db2 for Linux, UNIX, and Windows: Your data will not be replicated if you override the encoding for GRAPHIC, VARGRAPHIC, and DBCLOB columns.
  • For CDC Replication products that support XML replication, CDC Replication can only replicate XML compliant data to XML column types. Please see the XML specification for the compliance criteria.
  • CDC Replication will respect the mappings and apply the data according to the character set that is configured for the data. CDC Replication does not validate that the character set can be inserted correctly into the column.
  • Target tables must use the correct length values. Databases use character length semantics, byte length semantics, or both.
  • CDC Replication version 6.5 and later performs encoding conversion on the target by default, with an option to specify the source. This is a change in behavior from previous releases of CDC Replication that always performs encoding conversion on the source with no option to specify the target. Encoding conversion is a CPU intensive activity and you should take this into consideration when deciding where encoding conversion will take place.
  • Before using MBCS functionality in CDC Replication, you must ensure that your operating system, database, and all tools used to enter data (such as a terminal) are properly configured for your MBCS environment by a system administrator. Otherwise, unexpected behavior may result.
  • Java™ class user exits in CDC Replication support MBCS character data. All character data is converted to Java String objects.
  • When overriding database default character encodings, the specified encoding must be one that is supported by the database itself.
  • The CDC Replication Engine for FlexRep does not support overriding character encodings.