Explore topic-wise InterviewSolutions in .

DIMENSION tables are tables in a STAR schema of a data warehouse that contains keys, values, and attributes of DIMENSIONS. A dimension table generally contains the DESCRIPTION or textual information about the facts contained within a FACT table. 

The star schema comprises ONE or more dimensions and one fact table and is considered the simplest data warehouse schema. It is so-called because of its star-like shape, with RADIAL points radiating from a center. A fact table is at the core of the star and DIMENSION TABLES are at its points. The APPROACH is most commonly used to build data warehouses and dimensional data marts.

PARALLEL data processing improves the PERFORMANCE of PowerCenter with the Informatica PowerCenter Partitioning Option. With the partitioning option, a LARGE data set can be DIVIDED into smaller parts that can be processed in parallel, which improves overall performance. In addition to optimizing SESSIONS, it helps improve server performance and efficiency. 

When a mapping contains a LOT of requirements, which are BASED on too many dependencies, it is considered complex. Even with just a few transformations, a mapping can be complex; it doesn't NEED HUNDREDS of transformations. When the requirement has a lot of business requirements and constraints, mapping becomes complex. Complex mapping also encompasses slowly CHANGING dimensions. Complex mapping consists of the following three features.  

• Large and complex requirements
• Complex business logic
• Several transformations

Unlike full data loading, where all data is processed every time the data is loaded, incremental data loading involves loading only selective data (either updated or created new) from the source to the TARGET system. This method provides the following benefits: 

• ETL (Extract, transform, and load) process overhead can be reduced by selectively loading data, reducing runtime overall.
• Several factors can lead to an ETL load process failing or CAUSING errors. The likelihood of risk involved is reduced by the selective processing of the data.
• Data accuracy is PRESERVED in the historical record. Therefore, it BECOMES easy to determine the amount of data processed over time.

Workflow Manager ALLOWS you to CREATE the following types of tasks so that you can design a workflow: 

• Assignment task: A value is assigned to a workflow variable via this task type.
• Command task: This task executes a shell command during workflow execution.
• Control task: It halts or aborts workflow execution.
• Decision task: It describes a condition to be evaluated.
• Email task: This is used during workflow execution to send emails.
• Event-Raise task: This task NOTIFIES Event-Wait about the occurrence of an event.
• Event-Wait task: It waits for an event to COMPLETE before executing the next task.
• Session tasks: These tasks are used to run MAPPINGS created in Designer.
• Timer task: This task waits for an already timed event to occur.

Workflow in Informatica is typically seen as a set of interconnected tasks that all need to execute in a specific order or a proper sequence. In every workflow, a start task, as well as other tasks linked to it, are triggered when it's executed. A workflow represents a business's internal routine practices, GENERATES output data, and performs routine management tasks. The workflow monitor is a component of Informatica that can be used to see how well the workflow is performing. You can create WORKFLOWS both manually and automatically in the Workflow Manager. 

To HELP you develop a workflow, the Workflow Manager OFFERS the following tools:  

• Task Developer: This tool allows you to create workflow tasks.
• Worklet Designer: Worklet designer is an option in Workflow Manager which combines (groups) MULTIPLE tasks together to form a worklet. The term worklet refers to an object that groups multiple tasks together. Unlike workflows, worklets don't include scheduling information. It is possible to nest worklets inside workflows.
• Workflow Designer: This tool creates workflows by connecting tasks to links in the Workflow Designer. While developing a workflow, you can also create tasks in the Workflow Designer.

PowerCenter Integration Service (PCIS) started an operating system PROCESS, known as DTM (Data Transformation MANAGER) process or pmdtm process to run sessions. Its primary ROLE is CREATING and managing THREADS responsible for carrying out session tasks. Among the tasks performed by DTM are:   

• Read the session information
• Form dynamic partitions
• Create partition groups
• Validate code pages
• Run the processing threads
• Run post-session operations
• Send post-session email

In Informatica, TRACING levels determine how much data you want to write to the session LOG as you execute a workflow. Informatica's tracing level is a very IMPORTANT component as it aids in error analysis, locates bugs in the process, and can be set for EVERY transformation. Each transformation property WINDOW contains an option for tracing level. As shown below, there are different types of tracing levels:  

Router and FILTER are types of transformations offered by INFORMATICA. There are a few differences between them as given below:

A mapplet is a reusable object that contains a SET of transformations and is usually created using mapplet DESIGNER. Using it, you can reuse transformation logic ACROSS multiple MAPPINGS. Below are two TYPES of mapplets:  

• Active mapplet: This mapplet is created using an active transformation.
• Passive mapplet: This mapplet is created using a passive transformation.

<P>The Informatica features are accessed via four built-in command-line programs as given below: 

• pmcmd: This command allows you to complete the following tasks:
  • Start workflows.
  • Start workflow from a specific task.
  • Stop, Abort workflows and Sessions.
  • Schedule the workflows.
• infacmd: This command will let you access Informatica application services.
• infasetup: Using this command, you can complete INSTALLATION tasks such as defining a node or a domain.
• pmrep: By using this command, you can list repository objects, create, edit and delete GROUPS, or restore and delete REPOSITORIES. Overall, you can complete repository administration tasks.

In Informatica, a PMCMD command is used as FOLLOWS: 

• Start workflows 
  • pmcmd startworkflow -service informatica-integration-Service -d domain-name -u user-name -p password -f folder-name -w workflow-name 
• Start workflow from a specific task
  • pmcmd startask -service informatica-integration-Service -d domain-name -u user-name -p password -f folder-name -w workflow-name -startfrom task-name 
• Stop workflow and task
  • pmcmd stopworkflow -service informatica-integration-Service -d domain-name -u user-name -p password -f folder-name -w workflow-name 
  • pmcmd stoptask -service informatica-integration-Service -d domain-name -u user-name -p password -f folder-name -w workflow-name task-name 
• Schedule the workflows 
  • pmcmd scheduleworkflow -service informatica-integration-Service -d domain-name -u user-name -p password -f folder-name -w workflow-name 
• Aborting workflow and task
  • pmcmd abortworkflow -service informatica-integration-Service -d domain-name -u user-name -p password -f folder-name -w workflow-name 
  • pmcmd aborttask -service informatica-integration-Service -d domain-name -u user-name -p password -f folder-name -w workflow-name task-name 

There are different TYPES of Informatica lookup CACHES, such as STATIC and DYNAMIC. The following is a list of the caches: 

• Static Cache
• Dynamic Cache
• Persistent Cache
• Shared Cache
• Reached