What are breaking changes in a data schema?

Breaking changes in a data schema refer to modifications that can disrupt the existing structure and functionality of a database or data model. When there are modifications or deletions of existing fields, they can have a significant impact on applications or systems that depend on that data schema. For instance, if a field is removed or altered in a way that changes its data type, any code or queries that reference that field may fail or return incorrect results, causing potential system errors or inconsistencies.

In contrast, adding new features to the system or making general improvements typically does not qualify as breaking changes, as they generally enhance or extend functionality without affecting existing operations. Similarly, changes aimed at improving user experience or data access that do not involve alterations to existing fields also do not create breaking changes. Thus, the correct choice reflects the critical nature of modifying or deleting fields in a data schema, which can lead to failures in dependent processes or applications.