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From Luke Han <luke...@gmail.com>
Subject Re: About Kylin Dimension Definition
Date Tue, 10 May 2016 07:01:07 GMT
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 <xujiao.mycafe@gmail.com> 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 <shaofengshi@apache.org>:
>
>> 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 <xujiao.mycafe@gmail.com>:
>>
>>> 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 <xujiao.mycafe@gmail.com>:
>>>
>>>> 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
>>
>>
>

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