Aggregate tables for columnar DB

[jdw89-cs]

I'm working with Mondrian on a columnar DB, means I have a big flat fully denormalized fact table that contains all facts and dimensions. Unfortunately, I am not able to use a aggregate table. When I collapse all dimensions in the aggregate table, Mondrian successfully recognizes the aggregate table. But when I keep e. g. the time dimension, Mondrian does not:

14:06:14,859 WARN  [AggTableManager] Recognizer.checkUnusedColumns: Candidate aggregate table 'agg_days_flattened' for fact table 'flattened' has a column 'dayofMonth' with unknown usage.
14:06:14,860 WARN  [AggTableManager] Recognizer.checkUnusedColumns: Candidate aggregate table 'agg_days_flattened' for fact table 'flattened' has a column 'month' with unknown usage.
14:06:14,860 WARN  [AggTableManager] Recognizer.checkUnusedColumns: Candidate aggregate table 'agg_days_flattened' for fact table 'flattened' has a column 'year' with unknown usage.

Furthermore, the aggregate table is not used when I perform a corresponding MDX query. When I model the same cube with a classical star schema, everything works fine.
For me, it looks like Mondrian neads "true" foreignkey/primarykey mappings to work with agggregate tables, which do not apply to my szenario (big flat fully denormalized fact table).
Does anyone have an idea?