I think Mars' concern is right, we shouldn't introduce too complex concept for users.
As most of BI/DW experts, they are familiar to create dimension with different types: normal, hierarchy, derived... The "Aggregation Group" is in Advanced setting which should not open to Users (Modeler) directly. We should move back "hierarchy" to previous place and do some auto-gen stuff for Agg Group. Thanks. Best Regards! --------------------- Luke Han On Mon, May 9, 2016 at 11:15 PM, Mars J <[email protected]> wrote: > what's difference between pre-aggregation and post-aggregation ? > I have no experience in traditional BI and OLAP, not so clear to this > concept. > > 2016-05-10 13:51 GMT+08:00 ShaoFeng Shi <[email protected]>: > >> This is easy in my mind; Firstly you need understand the "derived" >> dimension; "Derived" dimensions can only be from lookup table, they will >> be derived from the pk/fk column at runtime; only the FK column will be >> built into cube; So if you use "derived", you don't need, and have no >> chance to declare them as hierarchy; >> >> Whether define them as a "derived" or "normal" + "hierarchy", depends on >> how you balance the pre-aggregation and post-aggregation. >> >> >> >> >> 2016-05-10 11:45 GMT+08:00 Mars J <[email protected]>: >> >>> It's very confused if I want to define a hierachy dim, I need to define >>> it be normal or derived and then add it to aggregation group for hierachy >>> dims. if this hierachy dims I want to define includes 3 columns, it will be >>> 3 dims if define it in normal dims or 1 dim if define it in derived dims. >>> So how to handle it ? >>> >>> 2016-05-10 10:53 GMT+08:00 Mars J <[email protected]>: >>> >>>> Hi, >>>> There is something confused me . In kylin 1.3 ,the dimension types >>>> are hierachy/derived/normal and mantory when create a cube in the >>>> dimensions step. In kylin 1.5.1 there 2 types including normal and derived >>>> in the dimensions step, and in the advanced setting , aggregation group has >>>> some aggregating manner of hierachy/mantory/joint. >>>> >>>> I test 1.3 including 2 derived dims and 2 hierachy dims(also has 3 >>>> columns each dims, level1-> level2 -> level3), I said it has 4 dims in the >>>> traditional BI way, but in kylin ,it's 10 dims. >>>> In kylin 1.5.1, I can't create hierachy dims directly, but I can >>>> create it for derived dims or normal dims first, then in the aggregroup , >>>> make it to hierachy dims. but I don't know how to count it in traditional >>>> BI way. >>>> >>>> We can discuss about the dims, and the different dims definition. >>>> >>> >>> >> >> >> -- >> Best regards, >> >> Shaofeng Shi >> >> >
