Re: How to build necessary cuboids rather than building all cuboidswhenadding or removing one dimension

[ShaoFeng Shi <sh...@apache.org>]

The Cube planner can run an "Optimize job" to add/remove new/deprecated
cuboids. As it won't change the Cube's structure (dimension/measures), so
it can run on an existing Cube.

If you want to add/remove dimension or measures, usually a new cube need be
created. If you want to reuse the existing cube's data, in the new cube,
you can just specify the new cuboids in some way.

Let's give an example; Say now I have a Cube A, which has two dimensions:
D1, D2;

It would have 3 cuboids (Kylin skips 0 cuboid):
[D1, D2], [D1], [D2]

Now I want to add new dimension D3, then I create Cube B with D1, D2, and
D3; By default, it would have 7 cuboids. If you want to just build the new
cuboids, in B you can define D3 as "mandatory" cuboids, then Cube B only
build the cuboids which have D3 presented:
[D1, D2, D3], [D1, D3], [D2, D3], [D3]

For queries that have no D3, Kylin will select cube A to answer. Others to
cube B. But you need to ensure cube A and B has the same range of data be
fed to ensure the data consistency.

Just my two cents.



Chao Long <wa...@qq.com> 于2018年9月28日周五 下午3:43写道：

> May i know your usage scenerio? As far as I know, if a cube has already
> been built, then the structure of the cube can not be modified, ie., you
> can't add or remove dimension. But if it has not been built yet, the
> structure can be modified. For now, it is not workable to build the
> modified cuboid only.
>
>
> ------------------ 原始邮件 ------------------
> *发件人:* "you Zhuang"<zh...@gmail.com>;
> *发送时间:* 2018年9月27日(星期四) 下午3:15
> *收件人:* "user"<us...@kylin.apache.org>;
> *主题:* Re: How to build necessary cuboids rather than building all
> cuboidswhenadding or removing one dimension
>
> Hybrid model seems difficult to be managed cohesively , is there a way to
> modify the cube , and then build modified cuboids only?
>
> On 26 Sep 2018, at 3:42 PM, Chao Long <wa...@qq.com> wrote:
>
> Hybrid is to consolidate history cube and new cube. And once a cube is
> built, its structure couldn’t be modified. To add/remove dimension, you
> need to clone a new cube, then add/remove in the new cube. And if you can
> accept the absence of new dimensions for historical data, you can build the
> new cube since the end time of the old cube. And then create a hybrid model
> over the old and new cube.
>
>
> ------------------ Original ------------------
> *From: * "you Zhuang"<zh...@gmail.com>;
> *Date: * Tue, Sep 25, 2018 10:39 AM
> *To: * "user"<us...@kylin.apache.org>;
> *Subject: * How to build necessary cuboids rather than building all
> cuboids whenadding or removing one dimension
>
> Hybrid cube does not affect all segments, and not cover removing
> situation. So how to build the related adding or removing dimension cuboids
> only?
>
>
>

-- 
Best regards,

Shaofeng Shi 史少锋