Data Synchronization enables developers to automatically sync the contents of a local table with the data from a REST service.

You can trigger Data Synchronization manually or on a regular schedule, using a scheduler job. Note that the CREATE JOB privilege must be granted to the application's parsing schema in order to execute REST source synchronizations on schedule.

Oracle APEX can create the local table based on the visible columns in the REST Data Source Data Profile. Since the table is a visible object in the database schema, developers can add indexes, change physical properties, or even add more columns.

If the table is not in sync with the Data Profile, Data Synchronization continues to work for columns present in both the table and the Data Profile (other columns are ignored). However, APEX generates SQL DDL statements to sync table columns back to the Data Profile. These statements can be added to the application as supporting objects.

After importing an application, REST Source Synchronizations are disabled. Learn how to enable synchronization after importing.

declare
    l_app_id number := {new application ID};
begin
    apex_session.create_session(
        p_app_id => l_app_id,
        p_page_id => {one of the application pages},
        p_username => '{workspace user}');

    apex_rest_source_sync.enable(
        p_application_id => l_app_id,
        p_module_static_id => '{REST Source static ID}');
end;

declare
    l_app_id number := {new application ID};
begin
    apex_session.create_session(
        p_app_id => l_app_id,
        p_page_id => {one of the application pages},
        p_username => '{workspace user}');

    apex_rest_source_sync.reschedule(
        p_application_id => l_app_id,
        p_module_static_id => '{REST Source static ID}');
        p_next_run_at => trunc( sysdate + 1 ), -- next midnight
end;

Configure REST synchronization to automatically sync a local table with data from a REST service.

To configure data synchronization:

1. Navigate to Shared Components:
   1. On the Workspace home page, click App Builder.
   2. Select an application.
   3. On the Application home page, click Shared Components.

   The Shared Components page appears.

2. View the REST Data Source:
   1. On the Shared Components page, find Data Sources and select REST Data Sources.
   2. On the REST Data Sources page, select the REST Source Name.
3. Click Manage Synchronization .
   The REST Synchronization page appears.
4. Under Details:
   1. Local Table Owner - Select the schema of the local table to synchronize data to. By default, the application Parsing Schema is used.
   2. Synchronize to - Select either New Table or Existing Table.
      • If Existing Table:
        • Table Name - Select an existing table name.
        • Nested Rows - Select to synchronize data to the local table.
        • Click Save.
      • If New Table:
        • Table Name - Enter the name of a new table.
        • Nested Rows - Select Nested Rows to synchronize data to the local table.

          If creating a new table, the message Table does not exist appears. Click Create Table.

        • Click Save.
   3. Table Name -
   4. Synchronization Type - Select a synchronization type:

      • Append - Append rows to the local table. This is typically used when no primary key has been defined in the data profile.

      • Merge - Merge rows into the local table. To use this option, the data profile must have a Primary Key defined. If a row for the given Primary Key value exists, the row is updated.. Otherwise the row is created.

      • Replace - Empty the local table before loading new data.

   5. Synchronization Schedule - Use the Database Scheduler Calendaring syntax to define repeating synchronization schedules, such as every Tuesday and Friday at 4:00 p.m. or the second Wednesday of every month.

      You can enter calendaring syntax manually or declaratively by using the Interval Builder to build simple expressions. To use the Interval Builder, click the Wrench icon.

      For more complex execution schedules, review details about the Scheduler Calendaring Syntax in DBMS_SCHEDULER PL/SQL package, and provide your expression manually.

      Note:

      To learn more about scheduler calendaring syntax, see DBMS_SCHEDULER Operational Notes in Oracle Database PL/SQL Packages and Types Reference

5. Under Steps - Click Add Step to pass parameter values or specific external filters to the REST Service.
   If no step is defined, the REST Data Source will be invoked once, with default parameters. If steps are defined, APEX will invoke the REST Data Source once for each step, and pass the configured parameters.
6. Under Advanced Settings:
   1. Commit Interval - Specify the commit interval to use during data synchronization. If not specified, the whole synchronization will be one transaction, with a commit after the last row. If an interval is specified, APEX will commit each time after the specified amount of rows have been processed.
   2. HTTP Request Limit - If required, provide a maximum number of HTTP requests to make for each synchronization step. If this limit is exceeded, synchronization will stop and logged as Incomplete.
      Note that due to the actual execution method, synchronization will exceed this limit by one request. For example, if you provide a limit of 10, synchronization will stop after the 11th request has been made.
   3. Enable Simple Rate Limiting - When enabled, APEX ensures that only a limited amount of HTTP requests is executed within the given time frame. This rate limiting is purely based on the number of HTTP requests being executed within a time frame. It does not look into HTTP response headers returned by the REST service.
7. To save your changes, click Save.
8. To execute REST Synchronization, click Save and Run.

View REST Synchronizations defined in the current application.

To view REST Synchronizations defined for the current application:

1. Select the application and navigate to Shared Components:
   1. On the Workspace home page, click App Builder.
   2. Select an application.
   3. On the Application home page, click Shared Components.

   The Shared Components page appears.

2. Under Tasks, click REST Synchronizations.
   The Synchronization page appears displaying REST synchronizations defined in the current application.

Clear synchronization settings to stop synchronization processing and reset all REST Data Source attributes related to synchronizations.

To clear synchronization settings:

1. Select the application and navigate to Shared Components:
   1. On the Workspace home page, click App Builder.
   2. Select an application.
   3. On the Application home page, click Shared Components
2. On the The Shared Components page, select REST Synchronizations from the Tasks list.
3. Select the REST Synchronization.
4. Click Clear Settings.

View a report of application components currently using the local synchronization table as their data source.

View the Synchronize Usage report:

1. Select the application and navigate to Shared Components:
   1. On the Workspace home page, click App Builder.
   2. Select an application.
   3. On the Application home page, click Shared Components
2. On the The Shared Components page, select REST Synchronizations from the Tasks list.
3. Select the REST Synchronization.
4. Under Details, click Synchronize Usage.
   A report appears showing application components currently using the local synchronization table as their data source.

Learn about the REST Synchronization log.

• About the REST Synchronization Log
  The REST Synchronization log records details of previously executed synchronizations.
• Purging the Synchronization Log
  Purge the REST Synchronization log.