Question

I’m working with a moderately sized database of about 60,000 records. I am working on building a mobile application which will be able to check out a single table into a compact .sdf on for viewing and altering on the device, then allow the user to sync their changes back up with the main server and receive any new information.

I have set it up with the Sync Framework using a WCF Service Library. When setting up the connection for some reason the database won’t let me check “Use SQL Server Change Tracking” and throws up the error:

“‘Unable to initialize the client database, because the schema for table ‘Inventory’ could >not be retrieved by the GetSchema() method of DbServerSyncProvider. Make sure that you can >establish a connection to the client database and that either the >SelectIncrementalInsertsCommand property or the SelectIncrementalUpdatesCommand property of >the SyncAdapter is specified correctly.”

So I leave it unchecked and set it to use some already created columns “AddDateTime” and “LastEditTime” it seems to work okay, and after a massive amount of tweaking I have it partially working. The changes on the device sync up perfectly with the database, updates, deletes, all get applied. However, changes on the server side…never get updated. I’ve made sure everything is set up right with the bidirectional setup so that shouldn’t be the problem. And, I let it sit overnight so the database received ~500 new records, this morning it actually synced the latest 24 entries to the database…out of 500 new. So that should be further proof that it’s able to receive information from the server, but for all useful purposes, it’s not.

I’ve tried pretty much everything and I’m honestly getting close to losing it. If anyone has any ideas they can throw out I can chase after I would be most grateful.

I’m not sure if I just need to go back and figure out why I can’t do it with the “SQL Server Change Tracking”. Or if there is a simple explanation for why it’s not actually syncing 99% of the changes on the server back to the client.

Also, the server database table schema can’t be altered as a lot of other services use it. But the compact database can be whatever the heck in needs to be to just store the table and sync properly in both directions.

Thank you!!

Quick Overview:

• Using WCF and syncing without SQL Server Change Tracking (Fully enabled on server and database)
• Syncing changes from client to server works perfectly
• Syncing from server back to the client not so much: out of 500 new entries overnight, on a sync it downloaded 24.

EDIT: JuneT got me thinking about the time and their anchors. When I synced this morning it pulled 54 of about 300 new added records. I went in to the line (there are about 60 or so columns, so I removed them for readability, this is kind of a joke)

this.SelectIncrementalUpdatesCommand.CommandText = @”SELECT [Value], [Value], [Value] FROM >TABLE WHERE ([LastEditDate] > @sync_last_received_anchor AND [LastEditDate] <= >@sync_new_received_anchor AND [AddDateTime] <= @sync_last_received_anchor)”;

And replaced @sync_last_received_anchor with two DIFFERENT times. Upon syncing it now returns the rows trapped between those two and took out the middle one giving me:

this.SelectIncrementalUpdatesCommand.CommandText = @”SELECT[Value], [Value], [Value] FROM >TABLE WHERE ([LastEditDate] > ‘2012-06-13 01:03:07.470’ AND [AddDateTime] <= ‘2012-06-14 >08:54:27.727’)”; (NOTE: The second date is just the current time now)

Though it returned a few hundred more rows than initially planned (set the date gap for 600, it returned just over 800). It does in fact sync the client up with the the new server changes.

Can anyone explain why I can’t use @sync_last_received_anchor and what I should be looking for. I suppose I could always add box that allows the user to select the date to begin updating from? Or maybe add some sort of xml file to store the sync date that would be updated anytime a sync was -successfully- completed?

Thanks!

EDIT:
Ran the SQL profiler on it…the date (@sync_last_received_anchor) is getting set to 8 hours ahead of whatever time it really is. I have no idea how or why it’s doing this, but that would definitely make sense.

Answer 1

Turns out the anchors are collected like this:

this.SelectNewAnchorCommand.CommandText = “Select @sync_new_received_anchor = GETUTCDATE()”;

That UTC date is what was causing the 8 hours gap. To fix it either change it to GETDATE(), or convert your columns to UTC time in the WHERE clause of the commands.