1. A computer-implemented method comprising: providing in an in memory database layer, a first data source of a first type and a second data source of a second type different from the first type, wherein the first data source comprises a multi-dimensional data structure and the second data source comprises other than a multi-dimensional data structure; providing in an application layer in communication with the in memory database layer, a multi-buffering system; and causing an abstract buffer component of the multi-buffering system, to support unified read or write access to the first data source and to the second data source by a consumer; wherein the abstract buffer component comprises a delta buffer configured to access the first data source, and an after image buffer configured to access the second data source, the abstract buffer component comprising a class distributing an operation comprising a current filter of a request from the consumer to the in memory database layer while retaining a handle, wherein the first data source of the first type and the second data source of the second type manage a calculation scenario containing information to calculate data relevant in a planning session and all parameters to obtain changed data in the planning session, the first data source of the first type and the second data source of the second type configured to return in the planning session, relevant data in the changed state and store the relevant data in the changed state upon receiving the request, wherein a storage mechanism passes the request unchanged to the in-memory database layer where the request does not commutate with a logged filter, the storage mechanism comprising a cache store configured to access the first data source, and a calculation scenario store configured to access the second data source; and wherein the storage mechanism reads data from the in memory database rather than the abstract buffer where an intersection of the logged filter with the current filter is found.