- MongoDB: transaction-based, nested, raw data. Scaling: replica set (+ arbiter) vertical, sharding horizontal.
- MySQL: simple relational/UI data where MongoDB is not already in the app.
- Valkey: accelerator / RT layer (Redis-protocol-compatible). No new Redis servers; existing ones migrate. Clients (ext-redis, predis, redis-py) unchanged.
- InfluxDB/Grafana: metrics.
- Zabbix: system, health, and syscheck monitoring.
- DB-link or REST-JSON.
- Adding a third-party package (composer, npm, pip/uv, go module from outside the org git host) needs explicit sign-off, for devs and agents alike: name package, license, and why it is needed.
- Paid/subscription data or processing services need explicit sign-off.
Handling is decided per app; no general rule.