The transaction log stores all changes made to a database, in the order in which they are made. In the event of media failure on a database file, the transaction log is essential for database recovery. It also makes your work more efficient. By default, the transaction log is placed in the same directory as the database file. It is created when the database is started for the first time on your Windows CE device.
When you copy an existing database to your Windows CE device, you can copy both the database and transaction log files. If you do not copy the transaction log file to the device, a new transaction log is created when you start the database on your Windows CE device. The new transaction log does not contain the information contained in the original transaction log. This can be problematic if the database was not shut down properly the last time it was used, or if the database is involved in synchronization. The best practice is to copy both the database and the transaction log file to the Windows CE device.