When download-only synchronization occurs, dbmlsync does not upload any database changes. However, it does upload information
about the schema and progress offset.
In addition, dbmlsync ensures that changes on the remote database are not overwritten during download-only synchronization.
It does this by scanning the log to detect rows with operations waiting to be uploaded. If any of these rows is modified by
the download, the download is rolled back and the synchronization fails. If the synchronization fails for this reason, you
must do a full synchronization to correct the problem.
When you have remotes that are synchronized by download-only synchronization, you should regularly do a full bi-directional
synchronization to reduce the amount of log that is scanned by the download-only synchronization. Otherwise, the download-only
synchronizations take an increasingly long time to complete.