Changing publishers   Problems can occur if you change the publisher user name on a consolidated database of a deployed and running SQL Remote system. If you need to change the consolidated database publisher user name, you must shut down the SQL Remote system and resynchronize all remote users.

Changing the user name of a publisher at a remote database causes problems for any subscriptions that the remote database is involved in, including the loss of information. If you need to change a remote database publisher user name, shut down the remote database and resynchronize the remote user. See Resynchronizing subscriptions.

Making restrictive changes to tables   You cannot make restrictive changes to tables. For example, do not drop a column or alter a column to disallow NULL values because messages can exist in the system that reference these columns.

Making permissive changes to tables   You can make permissive changes using passthrough mode. Use passthrough mode to make the changes to the remote database schema and publications. Permissive changes include adding a new table or column, adding new users, resynchronizing users, dropping users, and changing the address, message type, or send frequency for a remote user. See SQL Remote passthrough mode.

Altering publications   Publication definitions must be maintained on both the consolidated and the remote databases. Altering publications in a running SQL Remote system can cause replication errors and can lead to a loss of data in the replication system.

Deleting subscriptions   You can delete a subscription, but you must use passthrough mode to remove the data on the remote database. See SQL Remote passthrough mode.

Unloading and reloading databases   You must ensure that the transaction log is properly maintained. See Rebuild databases involved in synchronization or replication.

Making changes in a multi-tier hierarchy   For information about re-extracting database schemas in a multi-tier hierarchy, see Extracting databases for a multi-tier hierarchy system.

For information about making schema changes using the passthrough mode, see Passthrough mode limitations.