FusionAuth uses Elasticsearch for searching users and entities, both of which can have custom data fields which can have arbitrary data types.

This adds flexibility to your user data model.

This video dives deep into what happens when you create a user with a custom field that has a long data type, and then create another user with the same field but is a string.

It also includes an example of setting "ignore_malformed" on the index and how that affects how you can search for the user and what data you can get back from the user.

You can learn more about ignore_malformed can be found here.

Learn more about the Elasticsearch engine here.