variable and parameters

Question

Hi

what is the difference between variable and parameters in adf

Answer 1

Parameters:

• Purpose: Parameters are values you pass into a pipeline at the start of execution. They remain constant during the pipeline's runtime and cannot be changed after the execution begins.
• Scope: They are pipeline-scoped, meaning they can be accessed throughout the pipeline but are set only once, when the pipeline is triggered.
• Use Case: Think of parameters as inputs to a pipeline that determine how it will behave. For example, you might pass the file name or a date range as parameters to a pipeline. Example:A pipeline that copies data from a file in Blob Storage. The file name is passed as a parameter, so different file names can be used each time the pipeline is triggered.

    
    "parameters": {
    
    "fileName": {
    
      "type": "string",
    
      "defaultValue": "defaultFileName.csv"
    
    }
    
    }
    
  

Variables:

• Purpose: Variables store values that can change during the pipeline's runtime. You can set or modify the value of a variable within different activities in the pipeline.
• Scope: Variables are also pipeline-scoped but can be updated at different points in the pipeline execution.
• Use Case: Think of variables as values that might change during pipeline execution. For example, you might want to track the status of a loop or dynamically update a value during runtime. Example:
  • A pipeline that processes multiple files. You can use a variable to keep track of which file is being processed in a loop.

  
    "variables": {
  
      "currentFile": {
  
        "type": "string",
  
        "defaultValue": ""
  
      }
  
    }
  
  

Key Difference:

• Parameters: Set once at the start of the pipeline and remain constant.
• Variables: Can be changed during the pipeline’s execution.

Useful Links:

1. ADF Parameters and Variables
2. How to use parameters in ADF
3. Azure Data Factory Variables

These resources provide step-by-step guides to help you work with parameters and variables in ADF.

Answer 2

@Vineet S

Thanks for reaching out to Microsoft Q&A.

In Azure Data Factory (ADF), parameters and variables serve distinct purposes, and understanding their differences is crucial for effective pipeline management. Here’s a breakdown:

Parameters

• Definition: Parameters are defined at the pipeline or activity level and are used to pass values into a pipeline at runtime.
• Modification: They cannot be changed during the execution of the pipeline. Once set, their values remain constant throughout the run.
• Usage: Parameters are typically used to control the behavior of the pipeline, such as specifying connection strings or file paths. They allow for dynamic configurations, enabling the same pipeline to be reused with different inputs.
• Example: If you have a parameter named SourceConnectionString, you can pass different connection strings when triggering the pipeline, allowing it to connect to various databases without modifying the pipeline itself.

Variables

• Definition: Variables are internal values that can be defined and modified within the pipeline during its execution.
• Modification: Unlike parameters, variables can be changed at any point in the pipeline using activities like “Set Variable.”
• Usage: They are useful for storing intermediate results, performing calculations, or controlling the flow of execution based on conditions.
• Example: You might create a variable called totalSales to store the result of a calculation during the pipeline run, which can then be used in subsequent activities.

Summary

• Scope: Parameters are external and fixed during execution, while variables are internal and flexible.
• Purpose: Use parameters for configuration and input, and variables for data manipulation and flow control.

Hope this helps. Do let us know if you any further queries.

---

If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.