Database compatibility across versions

There is no guarantee that a database created with an older version of Terracotta will work with a newer version. This means that upgrading an existing deployment of Terracotta can be a bit of a pain, since every dataset in the deployment must be re-ingested into a new database.

We could make this a bit easier, by making a migrate-db command, which takes an old db and creates a new one by re-ingesting everything using the keys and paths in the old db. Additionally, we could have an option for simply forcing a version bump in the db without re-ingesting (like --force-version-bump or so) for power-users who know that the new version is compatible with their database. This could be nice for large deployments, where re-ingesting everything might take days.

The release notes should also specify whether or not the new version is compatible with databases from the previous version.

[dionhaefner]

AFAICT this is not really a major concern for all practical purposes. Feel free to re-open if I’m mistaken.

[mrpgraae]

Thanks for the clarification.

Yes, part of my point is that migration scripts are probably not particularly useful for us. Incompatibility always means we need to re-compute metadata.

Good, we are on the same page then 😄