ACC2000: How to Make a Database Replicable

Database replication is a feature of Microsoft Jet database engine 3.0 and later. Microsoft Access 2000 uses the Jet 4.0 database engine.

Replication enables you to make copies of the databases (called replicas) so that users can work on their own copies at different locations. Replicas can be synchronized with other replicas (in the same set) to ensure that they have consistent, up-to-date records and objects from one replica to the next. When you replicate a database, your original database becomes the Design Master for the replica set.

To implement Microsoft Jet database engine replication, you need to convert a Microsoft Access database into a special, replicable format. There are three ways to make a database replicable:

1. You can drag the database file (.mdb) to the Briefcase in Microsoft Windows 95, Microsoft Windows 98, Microsoft Windows NT 4.0, or Microsoft Windows 2000.
2. You can use the Create Replica command in Microsoft Access (point to Replication on the Tools menu, and then click Create Replica).
3. You can use the Replication Manager available with Microsoft Office 2000 Developers.

When you convert a database to a replicable format, you are asked to make a backup copy of the database. You should click Yes to create the backup copy, because once the database is replicable, you may not be able to return the database to its non-replicated state.

The replication conversion process adds several components, modifies a few properties for existing objects, and adds new properties to a database. Specifically, replication makes the following changes to a database:

• The s_GUID field stores a globally unique identifier for each record. This is added to the table.
• The s_Lineage field stores binary information about the history of changes to the record. This is added to the table.
• The s_Generation field stores information about groups of changes. If a table has Memo or OLE data type fields, multiple s_Generation fields are added, one for each Memo or OLE field. This is added to the table.
• The s_ColLineage is used to manage column-level tracking for a table. If the table is using row-level tracking, this field is not added. This is added to the table.
• Several System tables are added to the database to record the history of exchanges between replicas, the location of other replicas in the replica set, and other information required by the Microsoft Jet database engine. This is added to the database container.
• The NewValues property of AutoNumber fields will change from Increment to Random. This prevents any new records from receiving the same value as other new records in different replicas. This change is made at the table level.
• The Properties collection in Data Access Objects (DAO) has five additional properties: DesignMasterID, KeepLocal, Replicable, ReplicaID, and ReplicationConflictFunction.
• The Replicable property for each object in the database is set to True.

For more information about creating replicas, click Microsoft Access Help on the Help menu, type create a replica of your database in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

For more information about changes made to your database when you use replication, click Microsoft Access Help on the Help menu, type changes to replicated databases in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.

For additional information about replication, click the article number below to view the article in the Microsoft Knowledge Base: