Federated Query Layer

The federated query layer introduces a single SQL-like interface across D1, Hyperdrive/Postgres, Iceberg/R2, and KV-backed datasets.

Routing Rules

• Prefix-based:

  • d1.table_name → D1
  • pg.table_name → Hyperdrive
  • iceberg.table_name → Iceberg catalog
  • kv.* → KV backend

• Query hint comment override:

  • -- @backend: d1

Security & Validation

• Admin query endpoints must enforce SELECT-only allowlists.
• Validate query origins and access tier before execution.
• Clamp row limits.

Example Queries

-- @backend: iceberg
SELECT * FROM iceberg.compilation_events WHERE status = 'error';

SELECT key, value FROM kv.cache WHERE key LIKE 'source:%';

Extending Backends

1. Implement IQueryEngine.
2. Register backend in createQueryRouter(...).
3. Add routing convention (prefix or hint policy).
4. Update docs with operational constraints.