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.
- 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
- 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.