Column Transforms

Transforms are optional pieces of logic that can be applied to a column to either alter its data or generate new separate data.

Supported Transformations

Coalesce supports all transformation functions supported by Snowflake. Transformation logic can be authored in several ways:

Inline by double-clicking in the Transform field.
Within the Column Editor.
Using Macros to encapsulate logic and reduce code duplication for frequently used transformations.

By default, if no transformation is specified, a column will reference the column specified in the Source column of the Mapping Grid.

The source of a column is typically displayed in the Source column of the Mapping Grid. However, sources can also be defined within transformations.

Source added in the Transformation field:
- The Source cell will be disabled.
- On hover, more information about the source and an explanation for the cell's disabled state are shown.
Source added in transformation using an alias:
- The Source column will show the resolved source and the alias.
- On hover, the alias will be displayed.
Source added in transformation and column referenced using alias and non-alias:
- The same source will be shown twice, with one source indicated as aliased.

When working with column transformations, keep the following best practices in mind:

Data Type Matching: Always set the data type of your column to match the expected output of your transformation.
Use Macros for Repeated Logic: If you find yourself using the same transformation logic frequently, consider creating a Macro to encapsulate that logic and reduce code duplication.
Be Aware of Source Definitions: Pay attention to where sources are defined (in the Source column or within transformations) to avoid conflicts and ensure your transformations behave as expected.
Leverage Aliases: When working with complex transformations, using aliases can make your code more readable and maintainable.