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Posted to dev@kylin.apache.org by Sachin Aggarwal <di...@gmail.com> on 2018/10/23 10:55:15 UTC

join column derived vs normal

Hi Team,

while creating cube what are recommendations across join column between
fact and dimension.
should we mark it as derived or normal while selecting it from dimension
column.
what factors play a role in making this decision.


-- 

Thanks & Regards

Sachin Aggarwal

Re: join column derived vs normal

Posted by 陶加涛 <ta...@gmail.com>.

Hi Sachin Aggarwal 

When a lookup table is stored as snapshot, all columns in that table will be taken as derived dimension by default during cube design.

Compare to normal dimension, derived dimension does not participate in cube calculation directly. Instead, it is represented by its FK (Foreign Key) in cube. That is why using derived dimensions can greatly reduce cube complexity. During query, derived dimensions have to be converted to their FKs first, causing a small panalty to performance.

---
Regards!
Aron Tao
 
 

On [DATE], "[NAME]" <[ADDRESS]> wrote:

    Hi Team,
    
    while creating cube what are recommendations across join column between
    fact and dimension.
    should we mark it as derived or normal while selecting it from dimension
    column.
    what factors play a role in making this decision.
    
    
    -- 
    
    Thanks & Regards
    
    Sachin Aggarwal

Re: join column derived vs normal

Posted by 陶加涛 <ta...@gmail.com>.

Hi Sachin Aggarwal 

When a lookup table is stored as snapshot, all columns in that table will be taken as derived dimension by default during cube design.

Compare to normal dimension, derived dimension does not participate in cube calculation directly. Instead, it is represented by its FK (Foreign Key) in cube. That is why using derived dimensions can greatly reduce cube complexity. During query, derived dimensions have to be converted to their FKs first, causing a small panalty to performance.

---
Regards!
Aron Tao
 
 

On [DATE], "[NAME]" <[ADDRESS]> wrote:

    Hi Team,
    
    while creating cube what are recommendations across join column between
    fact and dimension.
    should we mark it as derived or normal while selecting it from dimension
    column.
    what factors play a role in making this decision.
    
    
    -- 
    
    Thanks & Regards
    
    Sachin Aggarwal

回复：join column derived vs normal

Posted by Chao Long <wa...@qq.com>.

I hope this may help you.
http://kylin.apache.org/docs/howto/howto_optimize_cubes.html





------------------ 原始邮件 ------------------
发件人: "Sachin Aggarwal"<di...@gmail.com>;
发送时间: 2018年10月23日(星期二) 晚上7:25
收件人: "user"<us...@kylin.apache.org>;

主题: join column derived vs normal



Hi Team,

while creating cube what are recommendations across join column between
fact and dimension.
should we mark it as derived or normal while selecting it from dimension
column.
what factors play a role in making this decision.


-- 

Thanks & Regards

Sachin Aggarwal