Should I pivot/crosstab db data on the server or client?

I have a Silverlight 3 app using WCF RIA Services and Entity Framework for the data-layer.

I need to pivot some data and was wondering what 开发者_开发问答the best practice is: Should the service return pivoted data, or should it just return a standard entity set and the client do the pivoting? Bearing in mind that the data needs to be editable so I need to be able to "un-pivot" the data as well.

Thanks.

If your users are primarily going to view the pivot data and rarely edit then sending the pivoted data will be quicker and more responsive. However, if they will always be editing the data, then there seems little point in making 2 trips to the server.