Informatica Architecture
The
Power Center domain
It is a primary unit of the Administration.
Can have single and multiple domains.
It is a collection of nodes and services.
Nodes
A node is the logical
representation of a machine in a domain
One node in the domain acts as a
gateway node to receive service requests from clients and route them to the
appropriate service and node
Integration
Service:
Integration
Service does all the real job. It extracts data from sources, processes it
as per the business logic and loads data to targets.
Repository
Service:
Repository
Service is used to fetch the data from the repository and sends it back to
the requesting components (mostly client tools and
integration service)
Power
Center Repository:
Repository
is nothing but a relational database which stores all the metadata created
in Power Center.
Power
Center Client Tools:
The
Power Center Client consists of multiple tools.
Power
Center Administration Console:
This
is simply a web-based administration tool you can use to administer the Power
Center installation.
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. The Designer
provides a set of transformations that perform specific functions. For example,
an Aggregator transformation performs calculations on groups of data. Below are
the various transformations available in Informatica:
• Aggregator
• Custom
• Expression
• External Procedure
• Filter
• Input
• Joiner
• Lookup
• Normalizer
• 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 Transformation whenever 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 or the order they appear in the default query should not be changed in
overridden query.
Q. What is
aggregator transformation?
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 transformation
permits calculations on a rowby-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 session option 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 to
merge 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 column values
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 a
mapplet?
A. A mapplet is a
reusable object that is created using mapplet designer. The mapplet contains
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 reusable
transformation is stored
as a metadata separate from any other mapping that uses the
transformation. 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 to be 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.
Q. What are the types of loading in Informatica?
There
are two types of loading, 1. Normal loading and 2.
Bulk loading.
In
normal loading, it loads record by record and writes log for that. It takes
comparatively a longer time to load data to the target.
In
bulk loading, it loads number of records at a time to target database. It takes
less time to load data to target.
Q. What is aggregate cache in aggregator
transformation?
The aggregator stores data in the
aggregate cache until it completes aggregate calculations. When you run a
session that uses an aggregator transformation, the informatica server creates
index and data caches in memory to process the transformation. If the
informatica server requires more space, it stores overflow values in cache
files.
Q. What type of
repositories can be created using Informatica Repository Manager?
A. Informatica
PowerCenter includes following type of repositories:
• Standalone
Repository: A repository that functions individually and this is unrelated
to any other repositories.
• Global
Repository: This is a centralized repository in a domain. This repository
can
contain shared objects
across the repositories in a domain. The objects are shared through global
shortcuts.
• Local
Repository: Local repository is within a domain and it��s not a global repository.
Local repository can connect to a global repository using global shortcuts and
can use objects in its shared folders.
• Versioned
Repository: This can either be local or global repository but it allows
version control for the repository. A versioned repository can store multiple
copies, or versions of an object. This feature allows efficiently developing,
testing and deploying metadata in the production environment.
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