Doing OBIEE with Essbase as datasource, anybody who has experience?

Question

Hello guys
Does anybody have good experience dealing with essbase data on OBIEE? Essbase doesn't seem to be a relational database like oracle, data are stored as cube. One cube contains dimesion and fact attributes with hierarchical levels defined in essbase.
I don't have experience dealing with these type of scenario, therefore I run into a lot of issues when I try to create report on answers..
Typically, when I apply any conversation functions or "SQL expression" values on date column filters or contents (such as cast(column as date), or filter on current_date on SQL Expressions) and create reports with measures, I get errors: [nQSError: 42043] An external aggregate is found in an outer query block. (HY000)
If create reports only with date column alone with the above applied, I get errors like inconsistent data type or something..
I believe that for some reasons when OBIEE sends the query to essbase and get converted into MDX, something got lost in translations.
With the same environment, I imagine if I were to create some dynamic variables with select statement, it will also not work since there is no "column" and "table" in essbase the same way as in relational database. So how would I define dynamic variables with max sales or something?
So is there any help I can get in terms of dealing with essbase on obiee?
Any pointers will be greatly appreciated
Thanks

Answer 1

Without access to the rpd you're not going to get far. Yes, you can achieve both things, but it will mean writing MDX and to use MDX in both the filters and the columns is not something I'd recommend since you'll be facing loads of issues.
Date filter:
The "normal" function you're using won't work. That's for sure. You will have to wrap the whole thing into an EVALUATE and write MDX...like the Lag function I mentioned before. If your time dimension is just taken over from Essbase in the normal drag-and-drop way, then it won't be a full "time dimension" anyway.
A column formula along the lines of this:
EVALUATE('[Time Period].[2009-04-15].Lag(7)')
Measure calculation:
Again, without access to the rpd this will be pretty hard to do due to the question where the aggregation actually happens. Venkat wrote about that recently.
http://oraclebizint.wordpress.com/2009/04/06/oracle-bi-ee-10134-and-essbase-connectivity-understanding-aggregations-part-1/
http://oraclebizint.wordpress.com/2009/04/07/oracle-bi-ee-10134-and-essbase-connectivity-understanding-aggregations-part-2/
http://oraclebizint.wordpress.com/2009/04/09/oracle-bi-ee-10134-and-essbase-connectivity-understanding-aggregations-part-3/
http://oraclebizint.wordpress.com/2009/04/13/oracle-bi-ee-10134-and-essbase-connectivity-understanding-aggregations-part-4/
Cheers,
Christi@n