ACD (Add, Change, Delete) Replications are a special type of replication that track the operations done against a database rather than replicating the data itself.  When an ACD Replication is defined, a source table is defined and a special ACD target table is created in the target database.  The Event Producer will now monitor the source database for any transactions against the table specified in the ACD Replication and a record will be inserted into the ACD target table specifying each operation (Add, Change or Delete) that occurs for the transaction.  The ACD target table is a transaction log for the specified source table.

ACD Target Table Metadata

The ACD target table consists of all the columns from the source table preceded by five pre-defined columns that provide transaction log information.  The five columns are:

Column Name	Data Type	Description
CNX_ACD_TXID	VarChar(64)	Transaction ID from source database
CNX_ACD_SequenceNumber	Integer	Sequence number within transaction
CNX_ACD_TimeCreated	TimeStamp	Timestamp from source database
CNX_ACD_ChangeUser	WVarChar(256)	User ID that made the change in the source database
CNX_ACD_ChangeType	Char(1)	Type of change.  Possible values are A,B,C or D

CNX_ACD_TXID

• This is the transaction ID from the source database.  All operations within a transaction will have the same CNX_ACD_TXID

CNX_ACD_SequenceNumber

• Each operation within a transaction will have a sequence number denoting its position within a transaction.  For example, if a transaction contains an insert, an update and a delete in that order, the sequence number of the insert will be 1, update will be 2 and the delete will be 3.

CNX_ACD_TimeCreated

• This is the timestamp from the source database denoting the time the operation occurred.