What is a schema registry and GraphQL governance at scale?

A schema registry is a central repository that stores versioned GraphQL schemas and enforces governance policies. Apollo Studio is the most widely used registry — it tracks schema changes over time, validates new schemas against registered client operations (preventing breaking changes), and provides usage analytics showing which fields clients query. Governance at scale involves: establishing a schema review process where proposed changes are reviewed by an API design committee before merging; enforcing naming conventions (camelCase fields, PascalCase types, SCREAMING_SNAKE_CASE enum values) via linting tools like graphql-eslint; maintaining a deprecation lifecycle with SLAs for field removal; documenting all types and fields with descriptions in the SDL (they appear in introspection); and running schema checks in CI with tools like Rover CLI. For federation, each team owns their subgraph schema but the gateway team governs the composition rules and the shared entity types, balancing team autonomy with API coherence.