where do we use connected and un connected lookups

If return port only one then we can go for unconnected. More than one return port is not possible with Unconnected.  If more than one return port then go for Connected. 

 

where do we use semi and non additive facts

Additve: A masure can participate arithmatic calulatons using all or any demensions.

Ex: Sales profit

Semi additive: A masure can participate arithmatic calulatons using some demensions.

Ex: Sales amount

Non Additve:A masure can’t  participate arithmatic calulatons using demensions.

Ex: temparature

 

What is Entity relation?? How is works with Datawarehousing ETL modeling

:Entity is nothing but an Object, it has characteristics.We call entity in terms of Logical view.The entity is called as a table in terms of Physical view.

The Entity relationship is nothing but maintaining a primary key,foreign key relation between the tables for keeping the data and satisfying the Normal form.

There are 4 types of Entity Relationships.

1.One-One, 2.One-Many, 3.Many-One 4.Many-Many

In the Datawarehouse modeling Entity Relationship is nothing but,a Relationship between dimension and facts tables(ie:Primary,foreign key relations between these tables).

The fact table getting data from dimensions tables because it containing primary keys of dimension tables as a foreign keys for getting summarized data for each record.

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