Where the SharePoint External List data is stored?

Question

Last week I had a discussion with one of my colleagues about "Where the SharePoint external List data is stored?", Is it stored in a SharePoint list and the SharePoint is synchronizing the changes between it and the original source, or SharePoint is saving only the connection information to the source and works as a representation interface for the external data only?

If you look at the following architecture you can say that it is stored in the SharePoint

http://img51.imageshack.us/img51/3171/arch1.gif

But, if you look to the following architecture for the client app integration you can say that it's not stored in the SharePoint, since the client app is synchronizing with the data source directly

http://img59.imageshack.us/img59/1270/arch2.gif

Any comments will be appreciated.

Kind Regards,

Mahmoud

Answer 1

External list data is stored in the external system, and not in SharePoint. SharePoint stores connection information and the schema of the external data.

For client systems only, there is a cache component for the external data (using SQL CE). I think this is the source of the confusion.

Answer 2

It's worth noting that if you use the External Data Column then the data is stored against the list item within SharePoint.