design: cloud database testing strategy (Snowflake, BigQuery, Redshift, Databricks)

[dtsong]

Problem

5 of 13 drivers (Snowflake, BigQuery, Redshift, Databricks, Oracle) cannot be tested in CI — they require cloud credentials or enterprise licenses. Currently they have zero automated test coverage.

Options to Evaluate

1. Nightly CI with secrets — GitHub Actions secrets for cloud DB credentials, scheduled runs
2. Emulators/mocks — LocalStack (Redshift), BigQuery emulator, etc.
3. Manual acceptance testing — Documented test scripts for contributors to run
4. Hybrid — Dialect unit tests in CI + manual integration tests for releases

Deliverable

Design document or ADR recommending an approach, with cost/complexity/coverage tradeoffs.

Acceptance Criteria

• Strategy document covering all 5 cloud databases
• Cost estimate for CI credentials/infrastructure
• Recommended approach with rationale