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 > >
