Surrogate Key Generator stage
The Surrogate Key Generator stage is a processing stage that generates surrogate key columns and maintains the key source.
A surrogate key is a unique primary key that is not derived from the data that it represents, therefore changes to the data do not change the primary key. In a star schema database, surrogate keys are used to join a fact table to a dimension table.
The Surrogate Key Generator stage can have a single input link, a single output link, both an input link and an output link, or no links. Job design depends on the purpose of the stage.
You can use a Surrogate Key Generator stage to perform the following tasks:
- Create or delete the key source before other jobs run
- Update a state file with a range of key values
- Generate surrogate key columns and pass them to the next stage in the job
- View the contents of the state file
Generated keys are unsigned 64-bit integers. The key source can be a state file.
You can use the Surrogate Key Generator stage to update a state file.
When you double-click the stage, the details pane opens. The details pane has three tabs:
- This tab is always present and is used to specify general information about the stage.
- This tab is where you specify the details about the single input set from which you are selecting rows.
- This tab is where you specify details about the processed data that is being output from the stage.