What statement describes tolerant reads in schema drift handling?

• A. A mechanism to permanently fail on drift.
• B. A mechanism to enforce the current schema only.
• C. A mechanism that allows reading data when the schema has drifted, using defaults or evolving schemas.
• D. A mechanism that removes the data.

Answer: (C)

Tolerant reads are about letting data be read even when the stored schema has drifted. They provide compatibility by applying schema evolution rules, such as filling missing fields with defaults orNulls, mapping new fields, or casting types as needed. This means queries won’t fail just because the schema has changed over time; you can read older data with its original structure while still supporting newer schemas. For example, if a record originally had id and name, and later records add an email field, a tolerant read can return email as null or a default for old data, while still correctly reading newer records that include email. This is why the statement describing tolerant reads is that they allow reading data when the schema has drifted, using defaults or evolving schemas.