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From 高扬02 <gaoyan...@bianfeng.com>
Subject 答复: how to define a snowflake model
Date Fri, 19 Oct 2018 01:21:01 GMT
Hi Billy , Thanks for your reply.

I also found it in the jira https://issues.apache.org/jira/browse/KYLIN-1875 ,and I noticed
that" This limitation is a problem for many-to-many relationships", but this is exactly where
we are.

I tried to create a model with one fact table and another fact table as lookup table , there
was an error in step 4:build dimension dictionary , and the information is "the lookup table
dup key found".

Now in model , I set the measure column to be the dimension , not any more measure , but in
cube , I set the measure column to be the dimension and measure to query the raw data and
measure of the measure column , because we want not just the intersection of the measure columns
in two tables but the "count(distinct)" of them.

Is this solution permissible ? Is there any problems or pitfalls ? Or is there a better solution
? Thanks.

Best regards,
Yang Gao

-----邮件原件-----
发件人: Billy Liu [mailto:billyliu@apache.org] 
发送时间: 2018年10月18日 18:36
收件人: user <user@kylin.apache.org>
主题: Re: how to define a snowflake model

In snowflake model, there is only one fact table also. But you could define lookup table joins
with another lookup table.

If the query pattern between your two "fact" tables is fixed, just like factA left join with
factB. You could define factB as lookup table and skip the snapshot for this huge lookup table.

With Warm regards

Billy Liu

高扬02 <gaoyang02@bianfeng.com> 于2018年10月18日周四 上午11:36写道:
>
> Kylin 2.5.
>
> How to define a snowflake model ? I did not find the place to set it.
>
> I have two fact tables , now I must create two cubes , and query “cube join cube”.
>
> To query the raw data of the measure column for “join” sql ,Now I set the measure
column to be the dimension column also,because it takes too long to use the “query-push-down”.
>
> Please show me where to define a snowflake model.
>
> thanks.
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