Liquibase: can it automatically figure out that a rollback is needed instead of an update?

General Discussion
1

I don’t think you are missing anything.

One thing you might take a look at is the liquibase status command. The documentation says it will give you a count of unrun changesets, or a list of unrun changesets with the --verbose option. I don’t know if it will list “extra” changesets (this would be changesets that are marked as applied in the DATABASECHANGELOG table, but that do not exist in the changelog.xml). If it does show the ‘extra’ changesets, you could use that as an indication that rollback might be necessary. 

In that case, you would need to have a workflow where the changelog is packaged with the application, so that when you shipped version 2.0 of the app, it had version 2.0 of the changelog, and version 2.1 of the app had version 2.1 of the changelog. If you roll back the app from 2.1 to 2.0 by just re-installing app 2.0, you might be able to tell using the status command that a rollback of the database was necessary (the db changes for 2.1 would be in the DATABASECHANGELOG table, but not mentioned in the 2.0 changelog) but you would still need the 2.1 changelog (with any custom rollback tags required for the 2.1 ‘go forward changes’) in order to safely roll back the database from 2.1 to 2.0.

Hope this helps,

Steve Donie
Principal Software Engineer
Datical, Inc. http://www.datical.com/

2

Is there a way to make Liquibase figure out whether to run an “update” versus a “rollback”?

When we deploy a set of code in an environment, we want the related DB changes (using Liquibase update) to be applied in lockstep. We may sometimes need to roll back the code deployed, which simply involves deploying an older set of code (the older code overwrites the newer code). However in the case of Liquibase, running an update with an earlier changeset will not do anything since there is nothing new to be applied.  However, the DB still has changes related to the newer Liquibase changeset which might pose a problem (eg if the structure of a table was changed). In this case, we may specifically require to run a “rollback” instead of an “update” which requires human intervention.

Am I missing an option in Liquibase that would make my life easier?

3

Thanks Steve, this helps a lot!

4

Thanks Steve, this helps a lot!