Lightning Connect external data sources are available in: Developer Edition and for an extra cost in: Enterprise, Performance, and Unlimited Editions.
When users create, modify, or delete external object records via the user interface, the operations occur synchronously, as with standard and custom object records. When developers use Apex to manipulate external object records, asynchronous timing and an active background queue minimize potential save conflicts.
A new set of Apex methods and keywords handles potential timing issues with write execution. Apex also lets you retrieve the results of delete and upsert operations. The BackgroundOperation object lets you monitor job progress for write operations via the API or SOQL.
It’s easy to make external objects writable. From Setup, enter External in the Quick Find box, then select External Data Source. By default, external objects associated with external data sources are read only. When you create or edit an external data source, you can make all its associated external objects writable. Select Allow Create, Edit, and Delete on the External Data Source page, as shown.