control is actually an ASP.NET server-side wrapper of the Kendo UI charting widget
and that is why there are many differences with the older RadChart in the performance, UI and functionality. Fortunately the advantages of the RadHtmlChart prevail the ones in the older control and they are constantly increasing with each Q. See details in the release notes
and in make a test of the new functionality in our Q3 2014 beta
Currently our efforts are put mainly on developing the chart's UI for data visualizing, the client-side functionality as well as the server-side wrapper rather than implementing custom server-side functionality. As already stated data source grouping is a separate functionality that is not directly related to the charting domain. This is not so, however, with controls that display data only in tabular view because they must manipulate with the data itself through operations like filtering, paging, sorting, grouping, etc.
Note also that the data base design is different for the particular project requirements and needs and also the performance of the grouping is the same for an embedded or a custom functionality.
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