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SQL Anywhere 12.0.0 » MobiLink - Server Administration » Using MobiLink server technology » Synchronization techniques

 

Timestamp-based downloads

The timestamp method is the most useful general technique for efficient downloads. This technique involves tracking the last time that each user synchronized and only downloading rows that have changed since then.

MobiLink maintains a timestamp value indicating when each MobiLink user last downloaded data. This value is called the last download time.

See Using last download times in scripts.

 To implement timestamp-based synchronization for a table
  1. At the consolidated database, add a last_modified column that holds the most recent time the row was modified. The column is typically declared as follows:

    DBMS last modified column
    Adaptive Server Enterprise datetime
    IBM DB2 LUW timestamp
    Microsoft SQL Server datetime
    MySQL timestamp
    Oracle timestamp
    SQL Anywhere timestamp DEFAULT timestamp
  2. In scripts for the download_cursor and download_delete_cursor events, compare the first parameter to the value in the timestamp column.

 Example

Using last download times in scripts
Dealing with daylight savings time