I was wondering is there any way of doing multi-dimensional analysis in MongoDB? Besides using a middle SQL like layer to stage the data between MongoDB and the analysis engine.
I am trying to use a Pentaho with MongoDB for BI, but I worry about how to handle Multi-dimensional analysis or even if I should try to do it at all. I know that there were some plans for Mondrian to access directly mongodb but nothing has been implemented yet.
In Pentaho EE 5.1 due out sometime this half of the year analyzer will have native mongo support - but that is only EE.
Your other option is indeed to use a SQL layer, and optiq is a good choice for that. The Saiku guys have got mondrian running via optiq to Mongo - and have even built support for aggregations. Note: The native Pentaho support mentioned above does NOT use optiq.
Unfortunately there's few other options at this stage!