About degenerate dimensions on Kylin cubes

[Roberto Tardío <ro...@stratebi.com>]

Hi,

I have a question about how Kylin compute degenerate dimensions, i.e., 
dimensions on the fact fable that do not need dimension lookup table. 
These type of these dimension is "Normal" by default but, What is the 
cost of add this dimensions? I guess they are not used on the cuboids 
concept because they are naturally combinated on fact table, so the 
question are:

  * Do they add appreciable complexity to the construction process of
    the cube?
  * Do they affect the query latency over cube built in any way?

Thanks in advance!

-- 

*Roberto Tardío Olmos*

/Senior Big Data & Business Intelligence Consultant/
Avenida de Brasil, 17, Planta 16.28020 Madrid
Fijo: 91.788.34.10

Re: About degenerate dimensions on Kylin cubes

[Billy Liu <bi...@apache.org>]

Hi Roberto,

Degenerate dimensions on fact table is not supported I think. There is only
two types dimensions: "normal" and "derived". All "normla" dimensions will
be precaculated into cube. So it affects the construction cost and query
latency. If some column in fact table do not need to be dimension, you
could define it as "extended column". The "extended column" will not be
precaculated.

2017-11-04 18:04 GMT+08:00 Roberto Tardío <ro...@stratebi.com>:

> Hi,
>
> I have a question about how Kylin compute degenerate dimensions, i.e.,
> dimensions on the fact fable that do not need dimension lookup table. These
> type of these dimension is "Normal" by default but, What is the cost of add
> this dimensions? I guess they are not used on the cuboids concept because
> they are naturally combinated on fact table, so the question are:
>
>    - Do they add appreciable complexity to the construction process of
>    the cube?
>    - Do they affect the query latency over cube built in any way?
>
> Thanks in advance!
> --
>
> *Roberto Tardío Olmos*
> *Senior Big Data & Business Intelligence Consultant*
> Avenida de Brasil, 17
> <https://maps.google.com/?q=Avenida+de+Brasil,+17&entry=gmail&source=g>,
> Planta 16.28020 Madrid
> Fijo: 91.788.34.10
>