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Q. How can you define a transformation? What are different types of

transformations available in Informatica?

A. A transformation is a repository object that generates, modifies, or passes data. TheDesigner provides a set of transformations that perform specific functions. For example,

an Aggregator transformation performs calculations on groups of data. Below are thevarious transformations available in Informatica:

Aggregator

Application Source Qualifier

Custom

Expression

External Procedure

Filter

Input

Joiner

Lookup Normalizer

Output

Rank

Router

Sequence Generator

Sorter

Source Qualifier

Stored Procedure

Transaction Control

Union

Update Strategy XML Generator

XML Parser

XML Source Qualifier

Q. What is a source qualifier? What is meant by Query Override?

A. Source Qualifier represents the rows that the PowerCenter Server reads from a

relational or flat file source when it runs a session. When a relational or a flat file source

definition is added to a mapping, it is connected to a Source Qualifier transformation.

PowerCenter Server generates a query for each Source Qualifier Transformationwhenever it runs the session. The default query is SELET statement containing all the

source columns. Source Qualifier has capability to override this default query by

changing the default settings of the transformation properties. The list of selected ports orthe order they appear in the default query should not be changed in overridden query.

Q. What is aggregator transformation?


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A. The Aggregator transformation allows performing aggregate calculations, such as

averages and sums. Unlike Expression Transformation, the Aggregator transformation

can only be used to perform calculations on groups. The Expression transformationpermits calculations on a row-by-row basis only.

Aggregator Transformation contains group by ports that indicate how to group the data.While grouping the data, the aggregator transformation outputs the last row of each group

unless otherwise specified in the transformation properties.

Various group by functions available in Informatica are : AVG, COUNT, FIRST, LAST,

MAX, MEDIAN, MIN, PERCENTILE, STDDEV, SUM, VARIANCE.

Q. What is Incremental Aggregation?

A. Whenever a session is created for a mapping Aggregate Transformation, the sessionoption for Incremental Aggregation can be enabled. When PowerCenter performs

incremental aggregation, it passes new source data through the mapping and uses

historical cache data to perform new aggregation calculations incrementally.

Q. How Union Transformation is used?

A. The union transformation is a multiple input group transformation that can be used tomerge data from various sources (or pipelines). This transformation works just like

UNION ALL statement in SQL, that is used to combine result set of two SELECT

statements.

Q. Can two flat files be joined with Joiner Transformation?

A. Yes, joiner transformation can be used to join data from two flat file sources.

Q. What is a look up transformation?

A. This transformation is used to lookup data in a flat file or a relational table, view or

synonym. It compares lookup transformation ports (input ports) to the source columnvalues based on the lookup condition. Later returned values can be passed to other

transformations.

Q. Can a lookup be done on Flat Files?

A. Yes.

Q. What is the difference between a connected look up and unconnected look up?


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A. Connected lookup takes input values directly from other transformations in the

pipleline.

Unconnected lookup doesnt take inputs directly from any other transformation, but itcan be used in any transformation (like expression) and can be invoked as a function

using :LKP expression. So, an unconnected lookup can be called multiple times in amapping.

Q. What is a mapplet?

A. A mapplet is a reusable object that is created using mapplet designer. The mappletcontains set of transformations and it allows us to reuse that transformation logic in

multiple mappings.

Q. What does reusable transformation mean?

A. Reusable transformations can be used multiple times in a mapping. The reusabletransformation is stored as a metadata separate from any other mapping that uses thetransformation. Whenever any changes to a reusable transformation are made, all the

mappings where the transformation is used will be invalidated.

Q. What is update strategy and what are the options for update strategy?

A. Informatica processes the source data row-by-row. By default every row is marked tobe inserted in the target table. If the row has to be updated/inserted based on some logic

Update Strategy transformation is used. The condition can be specified in Update

Strategy to mark the processed row for update or insert.

Following options are available for update strategy :

DD_INSERT : If this is used the Update Strategy flags the row for insertion.

Equivalent numeric value of DD_INSERT is 0.

DD_UPDATE : If this is used the Update Strategy flags the row for update.

Equivalent numeric value of DD_UPDATE is 1.

DD_DELETE : If this is used the Update Strategy flags the row for deletion.

Equivalent numeric value of DD_DELETE is 2.

DD_REJECT : If this is used the Update Strategy flags the row for rejection.

Equivalent numeric value of DD_REJECT is 3.

Ques.5> What are the types of loading in Informatica?

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Ans.>There are two types of loading in informatica, normal loading and bulk loading.

In normal loading record by record are loaded and writes log for that. In this longer time

is needed to load data to the target.

In bulk loading number of records are loaded at a time to target database. It takes lesstime to load data to the target than in normal loading.

Ques.6>Why do we use the lookup transformation? How can we improve session

performance in aggregator transformation?

Ans.>A lookup transformation is used for checking the matched values from the source

or target tables and check whether the record already existing in the table. It is also used

for updating the slowly changing dimensions and also performs some calculations.

Using Incremental Aggregation we create Sorted Input option to improve the

performance since performance is reduced using the caches.

Ques.11> What are two types of processes that runs the session?

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Ans.>The two types of processes that runs the session are Load Manager and DTM

process.

Load manager process starts the session, creates DTM process, and sends post session

email when the session completes.

DTM process creates threads to initialize the session, read, write and transform data andhandle pre-session and post-session operations.

Ques.12>What are the difference between joiner transformation and source

qualifier transformation?

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Ans.>In joiner transformation heterogeneous data sources can be joined but this cannotbe achieved incase of source qualifier transformation.


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We need matching keys to join two relational sources in source qualifier transformation

whereas this is not needed incase of joiner. Two relational sources should come from

same data source in source qualifier. We can join relational sources which are comingfrom different sources also.

Ques.13>What is Datadriven?

Ans.>The informatica server follows instructions coded into update strategy

transformations within the session mapping which determine how to flag records forinsert, update, delete or reject. If we do not choose data driven option setting, the

informatica server ignores all update strategy transformations in the mapping.

Ques.14>What are the types of mapping wizards that are provided in Informatica?

Ans.>The designer provide two mapping wizard.

Getting Started Wizard creates mapping to load static facts and dimension tables as wellas slowly growing dimension tables.

These are the New Features Of Informatica 8.1.1 ::

1--> Informatica PowerCenter 8 is service-oriented for modularity, scalability and

flexibility.

2--> The Repository Service and Integration Service (as replacement for Rep Server and

Informatica Server) can be run on different computers in a network (so called nodes),even redundantly.

3--> Management is centralized, that means services can be started and stopped on nodes

via a central web interface.

4-->Client Tools access the repository via that centralized machine, resources are

distributed dynamically.

5-->It has a support for unstructured data which includes spreadsheets, email, Microsoft

Word files, presentations and .PDF documents. It provides high availability, seamless fail

over, eliminating single points of failure.

6-->Informatica has now added more tightly integrated data profiling, cleansing, and

matching capabilities.

7-->A new web based administrative console has been added.

8-->Java transformation is introduced.


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9-->Ability to write a Custom Transformation in C++ or Java.

10-->Dynamic configuration of caches and partitioning

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