Sunday, November 13, 2011

Informatica Real time Interview Questions



Hi readers. These are the questions which normally i would expect by interviewee to know when i sit in panel. So what i would request my reader’s to start posting your answers to this questions in the discussion forum under informatica technical interview guidance tag and i’ll review them and only valid answers will be kept and rest will be deleted.
  1. Explain your Project?
  2. What are your Daily routines?
  3. How many mapping have you created all together in your project?
  4. In which account does your Project Fall?
  5. What is your Reporting Hierarchy?
  6. How many Complex Mapping’s have you created? Could you please me the situation for which you have developed that Complex mapping?
  7. What is your Involvement in Performance tuning of your Project?
  8. What is the Schema of your Project? And why did you opt for that particular schema?
  9. What are your Roles in this project?
  10. Can I have one situation which you have adopted by which performance has improved dramatically?
  11. Where you Involved in more than two projects simultaneously?
  12. Do you have any experience in the Production support?
  13. What kinds of Testing have you done on your Project (Unit or Integration or System or UAT)? And Enhancement’s were done after testing?
  14. How many Dimension Table are there in your Project and how are they linked to the fact table?
  15. How do we do the Fact Load?
  16. How did you implement CDC in your project?
  17. How does your Mapping in File to Load look like?
  18. How does your Mapping in Load to Stage look like?
  19. How does your Mapping in Stage to ODS look like?
  20. What is the size of your Data warehouse?
  21. What is your Daily feed size and weekly feed size?
  22. Which Approach (Top down or Bottom Up) was used in building your project?
  23. How do you access your source’s (are they Flat files or Relational)?
  24. Have you developed any Stored Procedure or triggers in this project? How did you use them and in which situation?
  25. Did your Project go live? What are the issues that you have faced while moving your project from the Test Environment to the Production Environment?
  26. What is the biggest Challenge that you encountered in this project?
  27. What is the scheduler tool you have used in this project? How did you schedule jobs using it?

ETL Life Cycle



The typical real-life ETL cycle consists of the following execution steps:
1. Cycle initiation
2. Build reference data
3. Extract (from sources)
4. Validate
5. Transform (clean, apply business rules, check for data integrity, create aggregates or disaggregates)
6. Stage (load into staging tables, if used)
7. Audit reports (for example, on compliance with business rules. Also, in case of failure, helps to diagnose/repair)
8. Publish (to target tables)
9. Archive
10. Clean up
Best practices
Four-layered approach for ETL architecture design
  • Functional layer: Core functional ETL processing (extract, transform, and load).
  • Operational management layer: Job-stream definition and management, parameters, scheduling, monitoring, communication and alerting.
  • Audit, balance and control (ABC) layer: Job-execution statistics, balancing and controls, rejects- and error-handling, codes management.
  • Utility layer: Common components supporting all other layers.
Use file-based ETL processing where possible
  • Storage costs relatively little
  • Intermediate files serve multiple purposes:
  • Used for testing and debugging
  • Used for restart and recover processing
  • Used to calculate control statistics
  • Helps to reduce dependencies - enables modular programming.
  • Allows flexibility for job-execution and -scheduling
  • Better performance if coded properly, and can take advantage of parallel processing capabilities when the need arises.
Use data-driven methods and minimize custom ETL coding
  • Parameter-driven jobs, functions, and job-control
  • Code definitions and mapping in database
  • Consideration for data-driven tables to support more complex code-mappings and business-rule application.
Qualities of a good ETL architecture design :
  • Performance
  • Scalable
  • Migratable
  • Recoverable (run_id, ...)
  • Operable (completion-codes for phases, re-running from checkpoints, etc.)
  • Auditable (in two dimensions: business requirements and technical troubleshooting)

Need for Speed: The Run. Limited Edition-CloneDVD (Pc/Multi8)





Need for Speed: The Run. Limited Edition-CloneDVD (Pc/Multi8)
Year 2011 | Pc Game | Eng/Rus/Ger/Spa/Fre/Ita... | Published by: Electronic Arts | Developed by: EA Black Box | 14.73 Gb
Genre: Arcade / Racing (Cars) / 3D Game

Adrenaline junkies and speed fiends will find themselves on the wrong side of the law when they race for their lives in Need for Speed: The Run. This game takes players on a heart-pounding cross-country race from San Francisco to New York. Players are lured into an underground world of illicit, high-stakes racing. The heat is on - and it isn't just the fuzz who are after you. Entering the race is just the beginning as you blow across borders, weave through dense urban traffic, rocket down icy mountain passes and navigate narrow canyons at breakneck speeds. Powered by DICE's state-of-the-art Frostbite 2 engine, Need for Speed: The Run takes the action racing genre to new heights with stunning visuals and car physics that hug the road even at top speeds all built around a gripping storyline. The cars are hot, the racing is intense and the story will have you at the edge of your seat ... all the way from the Golden Gate Bridge to the Empire State building.



Limited Edition - Key Features
You are in a battle for your life. You need an edge because, in The Run, every second counts. Your Limited Edition gives you access to three elite cars and will extend your game play with five exclusive challenges.


* Your Limited Edition Arsenal - The cops will see you in the Lamborghini Aventador, but will it matter? Open up this 700hp untamed beast on the highway and you'll see the fear in your rival's eyes. The Run across the U.S. wouldn't be complete without the Chevrolet Camaro ZL1. When your life is on the line the Camaro will be bullied by no one. Finally, who wouldn't want to drive the most highly anticipated car of 2011? The new Porsche 911 Carrera S and its raw power and pin point handling are exclusive to Need for Speed The Run.
* Your Limited Edition Events - Now that you have your elite cars, five exclusive racing events will put them to the test. The Limited Edition serves up fresh content, new opportunities to battle your friends on Autolog, and the chance to master your driving skills while earning bonus rewards and achievements.


Minimum Requirements
* OS: Windows Vista (Service Pack 2) 32-bit
* Processor: 3.0 GHz Intel Core 2 Duo or AMD Equivalent
* Memory: 3 GB
* Hard Drive: 18 GB
* Graphics card (AMD): 512 MB RAM ATI Radeon 4870 or higher performance
* Graphics card (NVIDIA): 512 MB RAM NVIDIA GeForce 8800 GT or higher performance
* Sound card: DirectX Compatible
* Keyboard
* DVD Rom Drive.


Recommended System Requirements
* OS: Windows 7 (Service Pack 1) 64-bit
* Processor: Quad-core CPU
* Memory: 4 GB
* Hard Drive: 18 GB
* Graphics Card: DirectX 11 compatible with 1024 MB RAM (NVIDIA GeForce GTX 560 or ATI Radeon 6950)
* Sound Card: DirectX Compatible
* Keyboard and Xbox 360 Controller for Windows
* DVD Rom Drive


Screenshot




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Try U R Hand's on Admin-Console

Repository Manager Tasks:

  • Add domain connection information
  • Add and connect to a repository
  • Work with Power Center domain and repository connections
  • Search for repository objects or keywords
  • View object dependencies
  • Compare repository objects
  • Truncate session and workflow log entries
  • View user connections
  • Release locks
  • Exchange metadata with other business intelligence tools

Add a repository to the Navigator, and then configure the domain connection information when we connect to the repository.

1.Adding a Repository to the Navigator :

1. In any of the Power Center Client tools, click Repository > Add.





2. Enter the name of the repository and a valid repository user name.

3. Click OK.

Before we can connect to the repository for the first time, we must configure the Connection information for the domain that the repository belongs to.






Description: clip_image007Description: clip_image008Description: clip_image030Description: clip_image031

2.Configuring a Domain Connection

  1. In a Power Center Client tool, select the Repositories node in the Navigator.
  2. Click Repository > Configure Domains to open the Configure Domains dialog box.
  3. Click the Add button. The Add Domain dialog box appears.
  4. Enter the domain name, gateway host name, and gateway port number.
  5. Click OK to add the domain connection.

3.Connecting to a Repository

  1. Launch a Power Center Client tool.
  2. Select the repository in the Navigator and click Repository > Connect, or double-click the repository.
  3. Enter a valid repository user name and password.
  4. Click Connect.

Click on more button to add, change or view domain information.

Description: clip_image014[1]Description: clip_image015[1]Description: clip_image028[1]Description: clip_image030[1]Description: clip_image031[1]




4.Viewing Object Dependencies

Before we change or delete repository objects, we can view dependencies to see the impact on other objects. For example, before you remove a session, we can find out which workflows use the session. We can view dependencies for repository objects in the Repository Manager, Workflow Manager, and Designer tools.

Steps:

  1. Connect to the repository.
  2. Select the object of use in navigator.
  3. Click Analyze and Select the dependency we want to view.

5.Validating Multiple Objects

We can validate multiple objects in the repository without fetching them into the workspace. We can save and optionally check in objects that change from invalid to valid status as a result of the validation. We can validate sessions, mappings, mapplets, workflows, and worklets.

Steps:

  1. Select the objects you want to validate.
  2. Click Analyze and Select Validate
  3. Select validation options from the Validate Objects dialog box
  4. Click Validate.
  5. Click a link to view the objects in the results group.

6.Comparing Repository Objects

We can compare two repository objects of the same type to identify differences between the objects. For example, we can compare two sessions to check for differences. When we compare two objects, the Repository Manager displays their attributes.

Steps:

  1. In the Repository Manager, connect to the repository.
  2. In the Navigator, select the object you want to compare.
  3. Click Edit > Compare Objects.
  4. Click Compare in the dialog box displayed.Description: clip_image011[2]

7.Truncating Workflow and Session Log Entries

When we configure a session or workflow to archive session logs or workflow logs, the Integration Service saves those logs in local directories. The repository also creates an entry for each saved workflow log and session log. If we move or delete a session log or workflow log from the workflow log directory or session log directory, we can remove the entries from the repository.

Steps:

  1. In the Repository Manager, select the workflow in the Navigator window or in the Main window.
  2. Choose Edit > Truncate Log. The Truncate Workflow Log dialog box appears.
  3. Choose to delete all workflow and session log entries or to delete all workflow and session log entries with an end time before a particular date.
  4. If you want to delete all entries older than a certain date, enter the date and time.
  5. Click OK.

8.Managing User Connections and Locks

In the Repository Manager, we can view and manage the following items:

Repository object locks: The repository locks repository objects and folders by user. The repository creates different types of locks depending on the task. The Repository Service locks and unlocks all objects in the repository.

User connections: Use the Repository Manager to monitor user connections to the repository. We can end connections when necessary.

Types of locks created:

1. In-use lock: Placed on objects we want to view

2. Write-intent lock: Placed on objects we want to modify.

3. Execute lock: Locks objects we want to run, such as workflows and sessions

Steps:

  1. Launch the Repository Manager and connect to the repository.
  2. Click Edit > Show User Connections or Show locks
  3. The locks or user connections will be displayed in a window.
  4. We can do the rest as per our need.

9.Managing Users and Groups

  1. In the Repository Manager, connect to a repository.
  2. Click Security > Manage Users and Privileges.
  3. Click the Groups tab to create Groups. or
  4. Click the Users tab to create Users
  5. Click the Privileges tab to give permissions to groups and users.
  6. Select the options available to add, edit, and remove users and groups.

There are two default repository user groups:

Administrators: This group initially contains two users that are created by default.

The default users are Administrator and the database user that created the repository. We cannot delete these users from the repository or remove them from the Administrators group.

Public: The Repository Manager does not create any default users in the Public group.

10 Working with Folders

We can create, Edit or delete folder as per our need.

  1. In the Repository Manager, connect to a repository.
  2. Click Folder > Create.

Enter the following information:







3. Click ok.

Services Behind Scene

INTEGRATION SERVICE PROCESS

The Integration Service starts an Integration Service process to run and monitor workflows. The Integration Service process accepts requests from the Power Center Client and from pmcmd. It performs the following tasks:

  • Manages workflow scheduling.
  • Locks and reads the workflow.
  • Reads the parameter file.
  • Creates the workflow log.
  • Runs workflow tasks and evaluates the conditional links connecting tasks.
  • Starts the DTM process or processes to run the session.
  • Writes historical run information to the repository.
  • Sends post-session email in the event of a DTM failure.

LOAD BALANCER

The Load Balancer is a component of the Integration Service that dispatches tasks to achieve optimal performance and scalability. When we run a workflow, the Load Balancer dispatches the Session, Command, and predefined Event-Wait tasks within the workflow.

The Load Balancer dispatches tasks in the order it receives them. When the Load Balancer needs to dispatch more Session and Command tasks than the Integration Service can run, it places the tasks it cannot run in a queue. When nodes become available, the Load Balancer dispatches tasks from the queue in the order determined by the workflow service level.

DTM PROCESS

When the workflow reaches a session, the Integration Service process starts the DTM process. The DTM is the process associated with the session task. The DTM process performs the following tasks:

  • Retrieves and validates session information from the repository.
  • Performs pushdown optimization when the session is configured for pushdown optimization.
  • Adds partitions to the session when the session is configured for dynamic partitioning.
  • Expands the service process variables, session parameters, and mapping variables and parameters.
  • Creates the session log.
  • Validates source and target code pages.
  • Verifies connection object permissions.
  • Runs pre-session shell commands, stored procedures, and SQL.
  • Sends a request to start worker DTM processes on other nodes when the session is configured to run on a grid.
  • Creates and run mapping, reader, writer, and transformation threads to extract, transform, and load data.
  • Runs post-session stored procedures, SQL, and shell commands.
  • Sends post-session email.

PROCESSING THREADS

The DTM allocates process memory for the session and divides it into buffers. This is also known as buffer memory. The default memory allocation is 12,000,000 bytes.

The DTM uses multiple threads to process data in a session. The main DTM thread is called the master thread.

The master thread can create the following types of threads:

  • Mapping Threads: One mapping thread for each session.
  • Pre- and Post-Session Threads: One thread created.
  • Reader Threads: One thread for each partition
  • Transformation Threads: One thread for each partition
  • Writer Threads: One thread for each partition

CODE PAGES and DATA MOVEMENT

A code page contains the encoding to specify characters in a set of one or more languages. An encoding is the assignment of a number to a character in the character set.

The Integration Service can move data in either ASCII or Unicode data movement mode. These modes determine how the Integration Service handles character data.

We choose the data movement mode in the Integration Service configuration settings. If we want to move multi byte data, choose Unicode data movement mode.

ASCII Data Movement Mode: In ASCII mode, the Integration Service recognizes 7-bit ASCII and EBCDIC characters and stores each character in a single byte.

Unicode Data Movement Mode: Use Unicode data movement mode when sources or targets use 8-bit or multi byte character sets and contain character data.

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