INFORMATICA INTERVIEW QUESTIONS AND ANSWERS
Informatica is one of the Leading ETL tool in the Market and one of the most used ETL tool used in Most of IT Companies .
It Comes Under Datawarehosuing and its one of the highly paid jobs . I am Posting Informatica Interview questions and answers for freshers and experienced which will be help full for them for cracking Informatica job interview questions .
1.
What do you mean by Enterprise Data Warehousing?
When the organization data is created at a
single point of access it is called as enterprise data warehousing. Data can be
provided with a global view to the server via a single source store. One
can do periodic analysis on that same source. It gives better results but
however the time required is high.
2.
What the difference is between a database, a data warehouse and a data mart?
Database
includes a set of sensibly affiliated data which is normally small in size as
compared to data warehouse. While in data warehouse there are assortments of
all sorts of data and data is taken out only according to the customer’s needs.
On the other hand datamart is also a set of data which is designed to
cater the needs of different domains. For instance an organization having
different chunk of data for its different departments i.e. sales, finance,
marketing etc.
3.
What is meant by a domain?
When
all related relationships and nodes are covered by a sole organizational point,
its called domain. Through this data management can be improved.
4.
What is the difference between a repository server and a powerhouse?
Repository
server controls the complete repository which includes tables, charts,
and various procedures etc. Its main function is to assure the repository
integrity and consistency. While a powerhouse server governs the
implementation of various processes among the factors of server’s database
repository.
5.
How many repositories can be created in informatica?
There can be any number of repositories in informatica but eventually it
depends on number of ports.
6. What is the benefit of partitioning
a session?
Partitioning a session means solo implementation sequences within the
session. It’s main purpose is to improve server’s operation and efficiency.
Other transformations including extractions and other outputs of single
partitions are carried out in parallel.
7. How are indexes created after
completing the load process?
For the purpose of creating indexes after the load process, command
tasks at session level can be used. Index creating scripts can be brought in
line with the session’s workflow or the post session implementation
sequence. Moreover this type of index creation cannot be controlled after the
load process at transformation level.
8. Explain sessions. Explain how
batches are used to combine executions?
A teaching set that needs to be implemented to convert data from a
source to a target is called a session. Session can be carried out using the
session’s manager or pmcmd command. Batch execution can be used to combine
sessions executions either in serial manner or in a parallel. Batches can have
different sessions carrying forward in a parallel or serial manner.
9. How many number of sessions can one
group in batches?
One can group any number of sessions but it would be easier for
migration if the number of sessions are lesser in a batch.
10. Explain the difference between
mapping parameter and mapping variable?
When values change during the session’s execution it’s
called a mapping variable. Upon completion the Informatica server stores the
end value of a variable and is reused when session restarts. Moreover those
values that do not change during the sessions execution are called mapping
parameters. Mapping procedure explains mapping parameters and their usage.
Values are allocated to these parameters before starting the session.
11.What is complex mapping?
Following are the features of complex mapping.
·
Difficult
requirements
·
Many
numbers of transformations
·
Complex
business logic
12. How can one identify whether
mapping is correct or not without connecting session?
One can find whether the session is correct or not without connecting
the session is with the help of debugging option.
13. Can one use mapping parameter or
variables created in one mapping into any other reusable transformation?
Yes, One can do because reusable transformation does not contain any
mapplet or mapping.
14. Explain the use of aggregator cache
file?
Aggregator transformations are handled in chunks of instructions during
each run. It stores transitional values which are found in local
buffer memory. Aggregators provides extra cache files for storing the
transformation values if extra memory is required.
15. Briefly describe lookup
transformation?
Lookup transformations are those transformations which have admission
right to RDBMS based data set. The server makes the access faster by using the
lookup tables to look at explicit table data or the database. Concluding
data is achieved by matching the look up condition for all look up ports
delivered during transformations.
16. What does role playing dimension
mean?
The dimensions that are utilized for playing diversified roles while
remaining in the same database domain are called role playing dimensions.
17. How can repository reports be accessed
without SQL or other transformations?
Ans:Repositoryreports are established by metadata reporter. There is no
need of SQL or other transformation since it is a web app.
18. What are the types of metadata that
stores in repository?
The types of metadata includes Source definition, Target definition,
Mappings, Mapplet, Transformations.
19. Explain the code page
compatibility?
When data moves from one code page to another provided that both code
pages have the same character sets then data loss cannot occur. All the
characteristics of source page must be available in the target page. Moreover
if all the characters of source page are not present in the target page
then it would be a subset and data loss will definitely occur during transformation
due the fact the two code pages are not compatible.
20. How can you validate all mappings
in the repository simultaneously?
All the mappings cannot be validated simultaneously because each time
only one mapping can be validated.
21. Briefly explain the Aggregator
transformation?
It allows one to do aggregate calculations such as sums, averages etc.
It is unlike expression transformation in which one can do calculations
in groups.
22. Describe Expression transformation?
Values can be calculated in single row before writing on the target in
this form of transformation. It can be used to perform non aggregate
calculations. Conditional statements can also be tested before output results
go to target tables.
23. What do you mean by filter
transformation?
It is a medium of filtering rows in a mapping. Data needs to be
transformed through filter transformation and then filter condition is
applied. Filter transformation contains all ports of input/output, and
the rows which meet the condition can only pass through that filter.
24. What is Joiner transformation?
Joiner
transformation combines two affiliated heterogeneous sources living in
different locations while a source qualifier transformation can combine data
emerging from a common source.
25. What is Lookup transformation?
It is used for
looking up data in a relational table through mapping. Lookup definition from
any relational database is imported from a source which has tendency of
connecting client and server. One can use multiple lookup transformation in a
mapping.
26. How Union Transformation is used?
Ans: It is a
diverse input group transformation which can be used to combine data from
different sources. It works like UNION All statement in SQL that is used to
combine result set of two SELECT statements.
27. What do you mean Incremental
Aggregation?
Option for
incremental aggregation is enabled whenever a session is created for a
mapping aggregate. Power center performs incremental aggregation through the
mapping and historical cache data to perform new aggregation calculations
incrementally.
28. What is the difference between a
connected look up and unconnected look up?
When the
inputs are taken directly from other transformations in the pipeline it is
called connected lookup. While unconnected lookup doesn’t take inputs directly
from other transformations, but it can be used in any transformations and
can be raised as a function using LKP expression. So it can be said that an
unconnected lookup can be called multiple times in mapping.
29. What is a mapplet?
A recyclable object
that is using mapplet designer is called a mapplet. It permits one to reuse the
transformation logic in multitude mappings moreover it also contains set of
transformations.
30.Briefly define reusable
transformation?
Reusable transformation
is used numerous times in mapping. It is different from other mappings which
use the transformation since it is stored as a metadata. The transformations
will be nullified in the mappings whenever any change in the reusable
transformation is made.
31. What does update strategy mean, and
what are the different option of it?
Row by row
processing is done by informatica. Every row is inserted in the target
table because it is marked as default. Update strategy is used whenever the row
has to be updated or inserted based on some sequence. Moreover the condition
must be specified in update strategy for the processed row to be marked as
updated or inserted.
32. What is the scenario which compels
informatica server to reject files?
This happens when it faces DD_Reject in update strategy
transformation. Moreover it disrupts the database constraint filed in the
rows was condensed.
33. What is surrogate key?
Surrogate key is a replacement for the natural prime key. It is a unique
identification for each row in the table. It is very beneficial because
the natural primary key can change which eventually makes update more
difficult. They are always used in form of a digit or integer.
34.What are the prerequisite tasks to
achieve the session partition?
In order to perform
session partition one need to configure the session to partition source data
and then installing the Informatica server machine in multifold CPU’s.
35. Which files are created during the
session rums by informatics server?
During session runs, the files created are namely Errors log, Bad file,
Workflow low and session log.
36. Briefly define a session
task?
It is a chunk of instruction the guides Power center server about how
and when to transfer data from sources to targets.
37. What does command task mean?
This specific task permits one or more than one shell commands in UNIX
or DOS in windows to run during the workflow.
38. What is standalone command task?
This task can be used anywhere in the workflow to run the shell
commands.
39. What is meant by pre and post
session shell command?
Command task can be called as the pre or post session shell command for
a session task. One can run it as pre session command r post session success
command or post session failure command.
40.What is predefined event?
It is a file-watch event. It waits for a specific file to arrive at a
specific location.
41. How can you define user defied
event?
User defined event can be described as a flow of tasks in the workflow.
Events can be created and then raised as need arises.
42. What is a work flow?
Ans: Work flow is a bunch of instructions that communicates server about
how to implement tasks.
43. What are the different tools in
workflow manager?
Following are the different tools in workflow manager namely
·
Task
Designer
·
Task
Developer
·
Workflow
Designer
44. Tell me any other tools for
scheduling purpose other than workflow manager pmcmd?
The tool for scheduling purpose other than workflow manager can be a
third party tool like ‘CONTROL M’.
45. What is OLAP (On-Line Analytical
Processing?
A method by which multi-dimensional analysis occurs.
46. What are the different types of
OLAP? Give an example?
ROLAP eg.BO, MOLAP eg.Cognos, HOLAP, DOLAP
47. What do you mean by worklet?
When the workflow tasks are grouped in a set, it is called as worklet.
Workflow tasks includes timer, decision, command, event wait, mail, session,
link, assignment, control etc.
48. What is the use of target designer?
Target Definition is created with the help of target designer.
49. Where can we find the throughput
option in informatica?
Throughput option can be found in informatica in workflow monitor. In
workflow monitor, right click on session, then click on get run properties and
under source/target statistics we can find throughput option.
50. What is target load order?
Ans: Target load order is specified on the basis of source qualifiers in
a mapping. If there are multifold source qualifiers linked to different targets
then one can entitle order in which informatica server loads data into targets.
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