SQL Server Integration Services provides some valuable features to enable you to control the workflow of your SSIS packages at a very granular level. Functionality that you might expect to be available only by scripting can often be accomplished by setting a few properties of a component. In addition, SSIS comes with powerful error-handling capabilities, the ability to log detailed information as the package runs, and debugging functionality that speeds up troubleshooting and design.
This chapter walks you through controlling the package workflow, beginning at the highest level using precedence constraints and then drilling down to event handling. You'll see how trappable events play a role in breakpoints, and how to perform exception handling for bad data in the Data Flow. Finally, you learn how these features can be used for troubleshooting, debugging, and enabling you to build robust SSIS packages.
Precedence constraints are the green, red, and blue connectors in the Control Flow that can be used to handle error conditions and the workflow of a package.
Be aware, precedence constraints look a lot like data paths in the Data Flow, but they are much different. On the one hand, precedence constraints define what tasks should be executed in which order; on the other hand, Data Flow paths define what transformations and destinations data should be routed to. Data Flow paths deal with moving data; precedence constraints deal with ...