This chapter was a mixture of various Continuous Delivery aspects that were not covered before. The key takeaways from the chapter are as follows:
- Databases are an essential part of most applications, and should therefore be included in the Continuous Delivery process.
- Database schema changes are stored in the version control system and managed by database migration tools.
- There are two types of database schema changes: backwards-compatible and backwards-incompatible. While the first type is simple, the second requires a bit of overhead (split to multiple migrations spread over time).
- A database should not be the central point of the whole system. The preferred solution is to provide each service with its own database.
- The delivery process should always be prepared for a rollback scenario.
- Three release patterns should always be considered: rolling updates, blue-green...
