Creating expressions
Compose allows you to create data transformations in several different places according to your needs. A transformation can either be a filter (i.e. excluding certain data) or an expression (i.e. manipulating a single record). The table below lists the places where transformations can be created and provides reasons for creating the transformation in each of the specified places.
Changes in a dimension expression or lookup of a column in a dimension are not updated retroactively. In order to update historical data, you would need to reload the data which could take a long time depending on the number of records and their history.
Where the Transformation is Created | Reasons to Create a Transformation There | When the Transformation is Applied |
---|---|---|
Replicate |
|
Before the data reaches the landing zone. |
Model |
|
Applied as an update to the staging tables after creating the mappings. |
Data Warehouse |
|
Between the landing zone and the staging zone. |
Data Mart |
|
Between the data warehouse and the data mart. |
See also Defining reusable transformations.
The following topics describe the Expression Builder: