NOTE: Unions, joins, and lookups are performed on a snapshot of the second dataset. If that dataset changes subsequently, its changes are not reflected in the joined dataset.
A union operation concatenates multiple datasets together. An example is below.
To union your dataset to another, click the Tools menu in the Transformer page. Then, click Union. See enter
union in the Choose a transformation textbox in the recipe panel. See Recipe Panel.
See Union Page.
A join operation brings together two datasets based on a column that appears in both datasets and contains the same unique values used to identify records. Based on the values in this column, called the primary key, records in the second dataset are joined to records in the first dataset. As part of the join definition, you may select the fields from both datasets to include, filtering out any duplicated or unnecessary fields in the combined dataset.
- A join is useful for pulling in selected fields from a second dataset based on matches of key values. These operations can be expensive to execute but can generate a much wider range of output datasets.
To join your dataset to with another, click the Tools menu in the Transformer page. Then, click Join. See enter
joinn in the Choose a transformation textbox in the recipe panel. See Recipe Panel.
See Join Page.
A lookup operation is used to pull in reference fields from another dataset based on the values contained in a selected column of the first dataset. These second datasets are typically static or changing infrequently.
NOTE: If a value in the column from the first dataset does not appear in the second dataset, the there is no corresponding value in the generated
When to use:
- Lookups are useful for referencing shared datasets whose meaning must be consistent across multiple datasets. You can use lookups to pull in customer or product master data (Customer name, address, etc.) based on CustomerId or ProductId values.
To perform a lookup from a column in your dataset, click open the caret next to the column name. Then, click column drop-down and select Lookup.... See Lookup Wizard.