INTERVIEW QUESTIONS DATA WAREHOUSING INFORMATICA DETAILS

Question: 1.can u explain one critical mapping?
2.performance issue which one is better? whether connected lookup tranformation or unconnected one?

Answer: it depends on your data and the type of operation u r doing.

If u need to calculate a value for all the rows or for the maximum rows coming out of the source then go for a connected lookup.

Or,if it is not so then go for unconnectd lookup.

Specially in conditional case like,

we have to get value for a field 'customer' from order tabel or from customer_data table,on the basis of following rule:

If customer_name is null then ,customer=customer_data.ustomer_Id

otherwise

customer=order.customer_name.

so in this case we will go for unconnected lookup

it depends on your data and the type of operation u r doing.

If u need to calculate a value for all the rows or for the maximum rows coming out of the source then go for a connected lookup.

Or,if it is not so then go for unconnectd lookup.

Specially in conditional case like,

we have to get value for a field 'customer' from order tabel or from customer_data table,on the basis of following rule:

If customer_name is null then ,customer=customer_data.ustomer_Id

otherwise

customer=order.customer_name.

so in this case we will go for unconnected lookup
Source: CoolInterview.com

Dimesions are
1.SCD
2.Rapidly changing Dimensions
3.junk Dimensions
4.Large Dimensions
5.Degenerated Dimensions
6.Conformed Dimensions. Source: CoolInterview.com

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