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Control Flow vs Data Flow

  • 18 December 2009
  • Author: BradSchacht
  • Number of views: 66738
  • 0 Comments

After my first day of SSIS training my boss walked into the office and said to me, "how was the first day of class".  To which I responded, "great!"  Then asked me, "so what is the difference between the control flow and data flow?"  This posed a simple, but foundational concept, of SSIS.  There are a few key things to remember when talking about the differences between control flow and data flow, and not just the completely obvious statement: data flow deals with data.  Hopefully if you are beginning in SSIS there will be something in the information below that will help you understand the differences just a little bit better.

Control Flow:

 

  • Process is the key:  precedence constraints control the project flow based on task completion, success or failure
  • Task 1 needs to complete before task 2 begins
  • Smallest unit of the control flow is a task
  • Control flow does not move data from task to task
  • Tasks are run in series if connected with precedence or in parallel
  • Package control flow is made up of containers and tasks connected with precedence constraints to control package flow
Data Flow:
  • Streaming
  • Unlink control flow, multiple components can process data at the same time
  • Smallest unit of the data flow is a component
  • Data flows move data, but are also tasks in the control flow, as such, their success or failure effects how your control flow operates
  • Data is moved and manipulated through transformations
  • Data is passed between each component in the data flow
  • Data flow is made up of source(s), transformations, and destinations.
Hopefully this will help you understand the differences between the control and data flows.

 

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