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SQL Anywhere 11.0.1 (Français) » UltraLite - Database Management and Reference » UltraLite as a MobiLink Client » UltraLite clients

 

Built-in UltraLite synchronization features

UltraLite contains MobiLink synchronization technology in the data management layer for UltraLite. Unlike SQL Anywhere remote, you do not need to increase the size of the UltraLite footprint to include synchronization functionality.

Important synchronization features built into the UltraLite runtime include a row-state tracking mechanism and the progress counter.

The row-state tracking mechanism

Tracking the state of tables and rows is particularly important for data synchronization. Each row in an UltraLite database has a one-byte marker to keep track of the state of the row. In addition to synchronization, UltraLite also uses the row states to control transaction processing and data recovery. See UltraLite row states.

The progress counter

UltraLite uses a progress counter to ensure robust synchronization. Each upload is given a unique number to identify it. This allows UltraLite to determine whether an upload was successful, when a communication error occurs.

When you first create a new database, UltraLite always sets the synchronization progress counter to zero. A progress counter value of zero identifies the database as a new UltraLite database, which tells the MobiLink server to reset its state information for this client.

Caution

Because UltraLite increments the progress counter each time a synchronization occurs, you cannot synchronize an UltraLite database to different consolidated databases. If the progress counter value is not zero and does not match that sequence number stored in the consolidated database, MobiLink synchronization reports an offset mismatch and synchronization fails.

See also