Replication Between Different Versions of SQL Server
Because you can upgrade servers running instances of Microsoft® SQL Server™ 2000 one at a time, you may have circumstances where servers in your replication topology are running different versions of SQL Server. You can replicate between different versions of SQL Server, but you are often limited to the functionality of the earliest version used.
For example, if you upgrade a Distributor to an instance of SQL Server 2000, but you have a Publisher running an instance of SQL Server version 7.0, and a Subscriber running an instance of SQL Server version 6.5, you are limited to the replication functionality of SQL Server 6.5 and unable to use features introduced in SQL Server 7.0 or SQL Server 2000. To use the new functionality, upgrade all servers used for replication to SQL Server 2000.
Features available in SQL Server 2000 are not supported with Subscribers running earlier versions of SQL Server. For example, if a merge publication contains features valid only in SQL Server 2000, and you use a push subscription to a Subscriber running SQL Server 7.0, backward compatibility is checked, and the Merge Agent will fail and display an error message indicating that the Subscriber does not meet the compatibility level. If a transactional publication contains features valid only in SQL Server 2000, and you use a push subscription to a Subscriber running SQL Server 7.0, backward compatibility is not checked, and the Distribution Agent may fail with an error message not related to backward compatibility, or the Distribution Agent may succeed, but transactional processing will fail at another point..
If a publication has active subscriptions to Subscribers running earlier versions of SQL Server, and you add a feature to the publication that is valid only for SQL Server 2000, the Merge Agents or Distribution Agents for the SQL Server 7.0 subscriptions will fail. Even if the SQL Server 2000 feature is installed, the agents will not run successfully. You must delete the subscription and re-create the publication and subscription.
Following are the different combinations of SQL Server versions you can have in a replication topology. When using SQL Server 6.5, you must have SQL Server Service Pack 4 or later installed, and when using SQL Server 7.0, you must have SQL Server Service Pack 1 or later installed. SQL Server version 6.0 can be used as an ODBC Subscriber in snapshot replication or transactional replication, but it cannot be a Publisher.
This table lists the combinations for snapshot replication and transactional replication.
| Combination 1 | Combination 2 | Combination 3 | |
| Publisher | SQL Server 6.5 | SQL Server 7.0 | SQL Server 2000 |
| Distributor | SQL Server 6.5 or SQL Server 7.0 | SQL Server 7.0 or SQL Server 2000 | SQL Server 2000 |
| Subscriber | SQL Server 6.0, SQL Server 6.5, SQL Server 7.0, or SQL Server 2000 | SQL Server 6.0, SQL Server 6.5, SQL Server 7.0, or SQL Server 2000 | SQL Server 6.0, SQL Server 6.5, SQL Server 7.0, or SQL Server 2000 |
This table lists the combinations for merge replication.
| Combination 1 | Combination 2 | Combination 3 | |
| Publisher | SQL Server 7.0 | SQL Server 2000 | SQL Server 2000 |
| Distributor | SQL Server 2000 | SQL Server 2000 | SQL Server 2000 |
| Subscriber | SQL Server 7.0 | SQL Server 7.0 | SQL Server 2000 |