Friday, November 14, 2008

Informatica Interview Questions And Answers III

What is difference between partioning of relatonal target and partitioning of file targets?
Partition's can be done on both relational and flat files.
Informatica supports following partitions
1.Database partitioning
4.Hash-Key partitioning
5.Key Range partitioning
All these are applicable for relational targets.For flat file only database partitioning is not applicable.
Informatica supports Nway partitioning.U can just specify the name of the target file and create the partitions, rest will be taken care by informatica session.
What are partition points?
Partition points mark the thread boundaries in a source pipeline and divide
the pipeline into stages.
What is parameter file?
Parameter file is to define the values for parameters and variables used in a session.A parameter
file is a file created by text editor such as word pad or notepad.
You can define the following values in parameter file:-
Maping parameters
Maping variables
session parameters.
Differences between Normalizer and Normalizer transformation.
Normalizer: It is a transormation mainly using for cobol sources,
it's change the rows into coloums and columns into rows
Normalization:To remove the retundancy and inconsitecy
Which transformation should we use to normalize the COBOL and relational sources?
Normalizer Transformation.
When you drag the COBOL source in to the mapping Designer workspace,the normalizer transformation automatically appears,creating input and output ports for every
column in the source.
Which transformation should u need while using the cobol sources as source defintions?
Normalizer transformaiton which is used to normalize the data.Since cobol sources r oftenly consists of Denormailzed data.
What is the difference between Narmal load and Bulk load?
Normal Load: Normal load will write information to the database log file so that if any recorvery is needed it is will be helpful. when the source file is a text file and loading data to a table,in such cases we should you normal load only, else the session will be failed.
Bulk Mode: Bulk load will not write information to the database log file so that if any recorvery is needed we can't do any thing in such cases.
compartivly Bulk load is pretty faster than normal load.
What are the join types in joiner transformation?
Normal (Default)
Master outer
Detail outer
Full outer.
What is the logic will you implement to laod the data in to one factv from 'n' number of dimension tables.
Noramally evey one use
!)slowly changing diemnsions
2)slowly growing dimensions
After draging the ports of three sources(sql server,oracle,informix) to a single source qualifier, can u map these three ports directly to target?
NO.Unless and until u join those three ports in source qualifier u cannot map them directly.
Can U use the maping parameters or variables created in one maping into another maping?
NO. You might want to use a workflow parameter/variable if you want it to be visible with other mappings/sessions
Can we lookup a table from a source qualifer transformation-unconnected lookup
No. we can't do.
I will explain you why.
1) Unless you assign the output of the source qualifier to another transformation or to target no way it will include the feild in the query.
2) source qualifier don't have any variables feilds to utalize as expression.
If i done any modifications for my table in back end does it reflect in informatca warehouse or maping desginer or source analyzer?
NO. Informatica is not at all concern with back end data base.It displays u all the information that is to be stored in repository.If want to reflect back end changes to informatica screens, again u have to import from back end to informatica by valid connection.And u have to replace the existing files with imported files.
Can you copy the batches?
Can you use the maping parameters or variables created in one maping into another maping?
Waht are main advantages and purpose of using Normalizer Transformation in Informatica?
Narmalizer Transformation is used mainly with COBOL sources where most of the time data is stored in de-normalized format. Also, Normalizer transformation can be used to create multiple rows from a single row of data
Can any one explain real time complain mappings or complex transformations in Informatica.
Specially in Sales Domain.
Most complex logic we use is denormalization. We dont have any Denormalizer transformation in INformatica. So we will have to use an aggregator followed by an expression. Apart from this, we use most of the complexicity in expression transformation involving lot of nested IIF's and Decode statements...another one is the union tranformation and joiner.
What is Micro Strategy? Why is it used for? Can any one explain in detail about it?
Micro strategy is again an BI tool whicl is a HOLAP... u can create 2 dimensional report and also cubes in here.......basically a reporting tool. IT HAS A FULL RANGE OF REPORTING ON WEB ALSO IN WINDOWS.
What are the real time problems generally come up while doing/running mapping/any transformation?can any body explain with example.
May be you will encounter with connection faliure, other then that i don't think so, cuzserver will handle all the syntex errors and Invalid mappings.

what are the difference between view and materialized view?
Materialized views are schema objects that can be used to summarize, precompute, replicate, and distribute data. E.g. to construct a data warehouse.
A materialized view provides indirect access to table data by storing the results of a query in a separate schema object. Unlike an ordinary view, which does not take up any storage space or contain any data
What are the different threads in DTM process?
Master thread: Creates and manages all other threads
Maping thread: One maping thread will be creates for each session.Fectchs session and maping information.
Pre and post session threads: This will be created to perform pre and post session operations.
Reader thread: One thread will be created for each partition of a source.It reads data from source.
Writer thread: It will be created to load data to the target.
Transformation thread: It will be created to tranform data.
what r the settiings that u use to cofigure the joiner transformation?
Master and detail source
Type of join
Condition of the join
the Joiner transformation supports the following join types, which you set in the Properties tab:
Normal (Default)
Master Outer
Detail Outer
Full Outer
What is difference between maplet and reusable transformation?
Maplet: one or more transformations
Reusable transformation: only one transformation
Define maping and sessions?
Maping: It is a set of source and target definitions linked by transformation objects that define the rules for transformation.
Session : It is a set of instructions that describe how and when to move data from source to targets.
What are the mapping paramaters and maping variables?
Maping parameter represents a constant value that You can define before running a session.A mapping parameter retains the same value throughout the entire session.
When you use the maping parameter ,U declare and use the parameter in a maping or maplet.Then define the value of parameter in a parameter file for the session.
Unlike a mapping parameter,a maping variable represents a value that can change throughout the session.The informatica server saves the value of maping variable to the
repository at the end of session run and uses that value next time you run the session.
What are the tasks that Loadmanger process will do?
Manages the session and batch scheduling: Whe you start the informatica server the load maneger launches and queries the repository for a list of sessions configured to run
on the informatica server.When you configure the session the loadmanager maintains list of list of sessions and session start times.When you sart a session loadmanger fetches the session information from the repository to perform the validations and verifications prior to starting DTM process.
Locking and reading the session: When the informatica server starts a session lodamaager locks the session from the repository.Locking prevents you starting the session again and again.
Reading the parameter file: If the session uses a parameter files,loadmanager reads the parameter file and verifies that the session level parematers are declared in the file
Verifies permission and privelleges: When the sesson starts load manger checks whether or not the user have privelleges to run the session.
Creating log files: Loadmanger creates logfile contains the status of session.

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