We're currently using the Microsoft Sync Framework 2.1 to sync data between a cloud solution and thick clients. Syncing is initiated by the clients and is download only. Both ends are using SQL Server and I'm using the SqlSyncScopeProvisioning class to provision scopes. We cannot guarantee that the clients will be running the latest version of our software, but we have full control of the cloud part and this will always be up to date.
We're considering supporting versioning of scopes so that if, for example, I modify a table to have a new column then I can keep any original scope (e.g. 'ScopeA_V1'), whilst adding another scope that covers all the same data as the first scope but also with the new column (e.g. 'ScopeA_V2'). This would allow older versions of the client to continue syncing until they had been upgraded.
In order to achieve this I'm designing data model changes in a specific way so that I can only add columns and tables, never remove, and all new columns must be nullable. In theory I think this should allow older versions of my scopes to carry on functioning even if they aren't syncing the new data.
I think I'm almost there but I've hit a stumbling block. When I provision the new versions of existing scopes I'm getting the correctly versioned copies of my SelectChanges stored procedure, but all the table specific stored procedures (not specific to scopes - i.e. tableA_update, tableA_delete, etc) are not being updated as I think the provisioner sees them as existing and doesn't think they need updated.
Is there a way I can get the provisioner to update the relevant stored procedures (_update, _insert, etc) so that it adds in the new parameters for the new columns with default values (null), allowing both the new and old versions of the scopes to use them?
Also if I do this then when the client is upgraded to the newer version, will it resync the new columns even though the rows have already been synced (albeit with nulls in the new columns)?
Or am I going about this the completely wrong way? Is there another way to make scopes backwards compatible with older versions?
Sync Framework out-the-box dont support updating scope definitions to accomodate schema changes. and creating new scope via the SetCreateProceduresForAdditionalScopeDefault will only create a new scope and a new _selectchanges stored procedure and but will re-use all the other stored procedures, tracking tables, triggers and UDT.
i wrote a series of blog posts on what needs to be changed to accomodate schema changes here: http://jtabadero.wordpress.com/2011/03/21/modifying-sync-framework-scope-definition-part-1-introduction/
the subsequent posts to that shows some ways to hack the provisioning scripts.
to answer your other question if the addition of a new column will resync that column or the row, the answer is no. first, change tracking is at the row level. second, adding a column will not fire the triggers that update the tracking tables that indicates if there are changes to be synched.