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Does LASR Star Schema support any other join condition besides the inner join

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Contributor
Posts: 62

Does LASR Star Schema support any other join condition besides the inner join

Hi everybody,

 

the question is:

does LASR Star Schema support any other join condition besides the inner join?

 

I don't know how to change this condition.

It seems to me so strange the impossibility to change the join condition in a star schema.

May be by editing the code? How?

 

Please help me.

Thank you very much.

 

Gabriele

Super User
Posts: 5,914

Re: Does LASR Star Schema support any other join condition besides the inner join

The general idea if star schemas is to use inner joins, one reason is performance.
Why do you need (I presume) outer joins?
Insert MISSING keys in your dimensions if you are not able to manage it in some other way during your ETL.
Data never sleeps
Contributor
Posts: 62

Re: Does LASR Star Schema support any other join condition besides the inner join

Hi LinusH,

 

thank you for your reply.

 

I have my fact table that is composed by cases, which are interactions between customers and the company.

Every case is identified by 3 values, but sometimes we have a 4th value.

This 4th value is registered in another table, dim_service.

 

I would like to join the fact table and the dim_service without loosing all the other cases.

 

Gabriele

Contributor
Posts: 62

Re: Does LASR Star Schema support any other join condition besides the inner join

Hi @LinusH,

 is it possible that the LASR Schema doesn't perform a Inner join.

I have this two table, the fact one which is about 10 M records and the dimension table which is 1 M records.

The Output table have the same records of the fact table.

Is it possible?

 

Could you help me?

 

Thank you

 

Contributor
Posts: 62

Re: Does LASR Star Schema support any other join condition besides the inner join

Hi @LinusH,

 

i keep on not understanding so well how the LASR Schema works.

I have one fact table 10M records and one dimension table 1M records. The cardinality it's 1 to n.

Viewing the output i understand that:

- VA performs an inner join

- VA performs a sort by key: using the output table in an Exploration if i filter for a specific value, which should have two rows (i tried the query on Guide), i can see only the first row.

 

Could you help me?

 

Thank you

Super User
Posts: 5,914

Re: Does LASR Star Schema support any other join condition besides the inner join

If you use no of observations as a way understanding your data model, your are on the wrong track.
The key here is to make sure that your fact table has a FK value on each row.
Data never sleeps
Contributor
Posts: 62

Re: Does LASR Star Schema support any other join condition besides the inner join

Hi @LinusH,

of course the table has a foreign key.

Maybe i was not able to express my problem in the correct way.

The problem here is that i'm not understanding the behaviour of VA performing Star Schema: the output it shows it is not what i expect.

 

Thank you for you support

 

  Gabriele

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