There's nothing automatic to tell you that there is data to synchronize. In addition to Ben's suggestion, another idea would be to query the SYS.SYSSYNC table at the remote database to get an idea of whether there might be changes. The following statement returns a result set that shows a simple status of your last synchronization :
select ss.site_name, sp.publication_name, ss.log_sent,ss.progress
from sys.syssync ss, sys.syspublication sp
where ss.publication_id = sp.publication_id
and ss.publication_id is not null
and ss.site_name is not null
If progress < log_sent, then the status of the last synchronization is unknown. The last upload may or may not have been applied at the consolidated, because the upload was sent, but no response was received from the MobiLink server. In this case, suggesting a synch isn't a bad idea.
If progress = log_sent, then the last synch was successful. Knowing this, you could check the value of db_property('CurrentRedoPos'), which will return the current log offset of the remote database. If this value is significantly higher than the progress value, there have been many operations applied to the database since the last synchronization, so there's a good chance that there is data to synchronize. There are lots of reasons why even a large difference in progress and db_property('CurrentRedoPos') could result in no actual data needing synchronization.
- The download from the ML Server is applied by dbmlsync after the progress value at the remote is updated by dbmlsync when the upload is confirmed by the ML Server. Operations applied in the download by dbmlsync are not synchronized back to the ML Server, so the entire offset range could just be the last download that was applied. This could be worked around by tracking the current log offset in the
sp_hook_dbmlsync_end hook when the exit code value in the #hook_dict table value is zero. This would tell you the log offset of the database after the download was applied, and you could now compare the saved value with the current log offset.
- All the operations in the transaction log could be operations on tables that are not synchronized.
- All the operations in the transaction log could have been rolled back.
My solution is not ideal. Tracking the changes to synchronized tables yourself is the best solution, but I thought I could offer an alternative that might be OK for your needs, with the advantage that you are not triggering an extra action on every operation performed on a synchronized table.