You are right, the advanced settings of aggregation groups are for cuboid pruning.
On Tue, May 10, 2016 at 4:17 PM, Mars J <[email protected]> wrote: > By the way, some pictures of docs for 1.5 is still v.1.3 like "Getting > Started -> Technical Concepts". > > Could u explain Agg Group 's meaning concisely even though there's > context of 'Each aggregation group is subset of dimensions, and build > cuboid with combinations inside. It aims at pruning for optimization" to > explain on the docs. > > But I still don't understand what the pruning for optimization mean or > what's this setting's advantage. > > In my mind , when build cuboid, if I don't define any dims in advanced > setting, it will build all cuboids, if I define any of hierarchy or > mantory or joint dimension, it will prune the cuboids which do not include > those dims defined in advanced setting. > > Is my understand for agg group right ? > > 2016-05-10 15:47 GMT+08:00 Mars J <[email protected]>: > >> Yes, Luke Han's idea of some auto-gen stuff for Agg Group is what I >> thinking about. But the auto-gen maybe difficult to define. >> In v1.3, it can create hierarchy dimensions by users themselves, users >> are very clear to know how the hierarchy-relations between various columns. >> Maybe u can auto-gen it first, and allow users to customize it. >> >> 2016-05-10 15:01 GMT+08:00 Luke Han <[email protected]>: >> >>> 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 >>>>> >>>>> >>>> >>> >> >
