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:

Stage
This tab is always present and is used to specify general information about the stage.
Input
This tab is where you specify the details about the single input set from which you are selecting rows.
Output
This tab is where you specify details about the processed data that is being output from the stage.