Making a Database Replicable

The first step in enabling replication is to create a design master. A design master is the only replica in the replica set which can make both schema and data changes, all other replicas can only make data changes to replicated objects. Making a database replicable makes the database a design master.

The following listings demonstrate how to make an existing database replicable.

DAO

Sub DAOMakeDesignMaster()

   Dim dbsNorthwind As DAO.Database

   Dim prpNew As DAO.Property

   ' Open database for exclusive access.

   Set dbsNorthwind = DBEngine.OpenDatabase(".\NorthWind.mdb", True)

   With dbsNorthwind

      ' If Replicable property doesn't exist, create it.

      ' Turn on error handling in case property exists.

      On Error Resume Next

      Set prpNew = .CreateProperty("Replicable", dbText, "T")

      .Properties.Append prpNew

      ' Set database Replicable property to True.

      .Properties("Replicable") = "T"

      .Close

   End With

End Sub

JRO

Sub JROMakeDesignMaster()

   Dim repMaster As New JRO.Replica

   ' Make the Northwind database replicable.

   ' If successful, this will create a connection to the

   ' database.

   repMaster.MakeReplicable ".\NorthWind.mdb", False

   Set repMaster = Nothing

End Sub

The JRO model simplifies the code for making a database replicable. To make a database replicable using DAO, the database must be opened, the Replicable property created and appended to the Properties collection of the database, and then the property set to "T". With JRO, a database can be made replicable with a single method, MakeReplicable.

The MakeReplicable method in JRO has an optional second parameter named ColumnTracking set to False in the example above. It indicates whether or not changes are tracked at the column level or row level. DAO did not expose the ability to track changes at the column level. Therefore, this parameter must be set to False if you want the same behavior as DAO. See the section, "New Features in JRO" for more information on column level tracking.

As with DAO, the process of making a database replicable using JRO cannot be reversed. It is recommended that you make a backup of your database before performing this operation.