Hierarchy versus list custom settings
Key Takeaway
Choose a Hierarchy custom setting when the value must change based on who is using the app, or when a formula field must use it. Formula fields can't use List custom settings.
Custom settings store small sets of custom data that apps can read cheaply from the application cache. They come in two types. List custom settings hold the same reference data for everyone in the org. Hierarchy custom settings hold values that can differ by org, profile, or user.
What custom settings are
Custom settings are a type of custom object. You can use them to create custom sets of data, or to associate custom data with the org, a profile, or a user.
Like custom objects, custom settings customize org data. But their data is exposed in the application cache, so you can read it without the cost of repeated database queries.
You can also read custom settings data with a SOQL query, but that works like querying a custom object and doesn't use the application cache. Reading List custom setting data from the application cache avoids SOQL queries that count against governor limits.
These features can use custom settings data:
- Formula fields
- Validation rules
- Flows
- Apex
- SOAP API