I’ve came across an excellent post by Boris Evelson on his blog: http://blogs.forrester.com/boris_evelson/10-03-31-i_forget_whats_in_memory (thanks to @vizubi) it’s an old one, but it makes perfectly clear what are the differences between the different in memory options. Evelson makes distinction between 5 types of in memory solutions, divides the solution providers over these 5 types and gives pro’s and cons for every option. Nice read!
In the same category: compare in-memory solutions is this post by Boris Evelson as well: http://blogs.forrester.com/boris_evelson/10-09-01-not_all_in_memory_analytics_tools_are_created_equal where Boris gives advice on how to compare in-memory solutions. Nice read as well, and nice comments from two Qlikview adepts