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SAP Sybase SQL Anywhere 16.0 » MobiLink - Getting Started » MobiLink technology » MobiLink plug-in for Sybase Central » Synchronization models


Limitations of synchronization models

The following are some restrictions of synchronization models:

  • Changes made outside the model cannot be redeployed   If you deploy a synchronization model and then make changes to it outside the model, those changes are not saved in the model. This practice is fine to use the model as a starting point, deploy, and then make all your changes outside the model. However, to redeploy the model, you are better off making your changes to your MobiLink project so that they are saved and can be redeployed.

  • Versions   A synchronization model can have only one version. See Script versions.

  • MobiLink system database   You cannot use a MobiLink system database that is separate from the consolidated database when deploying a synchronization model. See MobiLink system database.

  • Multiple publications   You cannot create multiple publications. After you have deployed your model, you can add more publications using non-model methods such as the CREATE PUBLICATION statement, but you cannot reverse-engineer these additions back into your model. See Publications.

  • Views   It is not possible to select a view when you are selecting consolidated database tables for table mappings.

  • Computed columns   You cannot upload to computed columns in a consolidated database table. If you deploy a synchronization model with computed columns, then the deployment may have errors creating the trigger used for timestamp-based downloads. You can either exclude the column from synchronization, or configure the table as download-only (and either use snapshot download or edit the generated consolidated SQL file to remove the computed column from the trigger definition).

    Copying computed columns causes a syntax error when deploying the new remote schema to create a new remote database. When dealing with computed columns you should do one of the following:

    • Deploy the synchronization model to an existing remote database.

    • Exclude the computed column from the remote schema. To synchronize a consolidated database table that has computed columns, you cannot upload to the table.

    The Microsoft SQL Server AdventureWorks sample database contains computed columns. Set the columns to be download-only or exclude the columns from synchronization when using this database to create a model.

  • Oracle XMLTYPE data type   The MobiLink plug-in for Sybase Central provides the following support for the Oracle XMLTYPE.

    • When an XMLTYPE column is chosen for a new remote schema or when editing column mappings, the displayed Data Type name is XMLTYPE.
    • XMLTYPE columns are mapped to columns of type XML in new SQL Anywhere remote databases. See Oracle data mapping.
    • The generated synchronization scripts work when XMLTYPE column values are 4 KB or less. For larger values, you must override the generated scripts in the synchronization model with scripts using the techniques described in Oracle XMLTYPE data type.

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