SSIS Precedence Constraints help guide execution of SSIS Package. They are used to create workflow within SSIS Package and as such essential for successful execution of SSIS Packages. SSIS Precedence Constraints waits till end of the prior step execution before deciding what process should be initiated next.
The SSIS Precedence Constraints relies on constraint value and conditional expression.
- Constraint Value defines the way SSIS Package reacts to the completion of two linked tasks. It looks at the execution finale of the prior tasks and makes a choice how to execute next task. There are three values that you can set:
- Success – task completed successfully and it is marked as green
- Completion – identifies completion of the precedent task and it is marked as blue
- Failure – identifies of prior task fail and it is marked as red
- Conditional Expression can be applied to a precedent constraint and allows determining SSIS Package workflow. SSIS Conditional Expression evaluates for a certain condition and executes package based on that condition. SSIS Conditional Expression has evaluation options that can be set to one of the following:
- Constraint – specifies that only constraint will be followed
- Expression - give ability to write an expression based on the condition
- ExpressionAndConstraint – determines expression and constraints that must be satisfied
- ExpressionOdConstraint – determines expression or constraints that must be satisfied