When a MobiLink client sends an updated row to the MobiLink server, it includes not only the new updated values (the post-image), but also a copy of the old row values (the pre-image) obtained either in the last download or from the row values existing prior to the first upload of this row. When the pre-image does not match the current values in the consolidated database, a conflict is detected.
There are several scripts provided to detect conflicts. The MobiLink server detects conflicts only if one of the following scripts is applied:
An upload_fetch or upload_fetch_column_conflict script.
An upload_update script that includes all non-primary key columns in the WHERE clause.
Detecting conflicts with upload_fetch scripts
Detecting conflicts with upload_update scripts