What are snapshots? What are materialized views & where do we use them? What is a materialized view log?

Materialized view is a view in wich data is also stored in some temp table.i.e if we will go with the View concept in DB in that we only store query and once we call View it extract data from DB.But In materialized View data is stored in some temp tables.

 

What are the various tools?

The various ETL tools are as follows.

Informatica
Datastage
Business Objects Data Integrator

OLAp tools are as follows.
Cognos
Business Objects 

 

Can Informatica load heterogeneous targets from heterogeneous sources?

yes! it loads from heterogeneous sources..

 

What is the difference between Power Center & Power Mart?

Power Center : we can connect to single and multiple Repositories, generally used in big Enterprices.
Power Mart : we can connect to only a single Repository.

 

What is a mapping, session, worklet, workflow, mapplet?

Mapping – represents the flow and transformation of data from source to taraget.
Mapplet – a group of transformations that can be called within a mapping.
Session – a task associated with a mapping to define the connections and other configurations for that mapping.
Workflow – controls the execution of tasks such as commands, emails and sessions.
Worklet – a workflow that can be called within a workflow.

 

What are parameter files ? Where do we use them?

Parameter file is any text file where u can define a value for the parameter defined in the informatica session, this parameter file can be referenced in the session properties,When the informatica sessions runs the values for the parameter is fetched from the specified file. For eg : $$ABC is defined in the infomatica mapping and the value for this variable is defined in the file called abc.txt as
[foldername_session_name]
ABC=’hello world”

In the session properties u can give in the parameter file name field abc.txt

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