# 7. Why there is no undo

[← 6. Baselining an existing database](06-baselining-an-existing-database.md) · [Index](../README.md) · Next: [8. Concurrent startup and locking →](08-concurrent-startup-and-locking.md)

`Flyway` (the Community, Apache-2.0-licensed `flyway-core` artifact this module depends on) has a
public method called `undo()`. It compiles. Its Javadoc reads like every other command. Nothing
in its signature suggests it won't work — and that's exactly the trap:
[`FlywayUndoTest`](../src/test/java/com/ankurm/dbmigrations/flyway/FlywayUndoTest.java) migrates a
real database, then calls `flyway.undo()` on it, and the call throws at runtime:

```
flyway.undo() threw: org.flywaydb.core.internal.license.FlywayRedgateEditionRequiredException
message: Flyway Redgate Edition Required: undo is not supported by OSS Edition
Download Redgate Edition for free: https://rd.gt/3GGIXhh
```

(from [`docs/output/06-flyway-undo-teams-required.txt`](output/06-flyway-undo-teams-required.txt))

`undo` isn't a special case singled out for this article — it's one of a whole family of commands
that ship as compiled, callable, do-nothing stubs in the Community jar.
[`FlywayCommunityCommandSurfaceTest`](../src/test/java/com/ankurm/dbmigrations/flyway/FlywayCommunityCommandSurfaceTest.java)
doesn't take that on faith either: it opens the actual `flyway-core` jar on the test classpath at
runtime and lists every class under `org.flywaydb.core.internal.proprietaryStubs`, so this list is
read off the artifact Maven Central serves, not copied from a marketing page:

```
- auth
- check
- deploy
- diff
- difftext
- generate
- licensingconfigurationextensionstub.class
- model
- offlinepermitconfigurationextensionstub.class
- pattokenconfigurationextensionstub.class
- prepare
- undo
```

(from [`docs/output/07-flyway-proprietary-stub-commands.txt`](output/07-flyway-proprietary-stub-commands.txt))

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  <text x="170" y="42" text-anchor="middle">flyway-core (Community, Apache-2.0)</text>
  <text x="40" y="65" font-size="12">migrate() ✓ real</text>
  <text x="40" y="85" font-size="12">baseline() ✓ real</text>
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  <text x="40" y="125" font-size="12">undo() — compiles, throws at runtime</text>
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  <text x="535" y="120" text-anchor="middle">FlywayRedgateEditionRequiredException</text>
  <text x="535" y="138" text-anchor="middle" font-size="11">only at the moment undo() is called</text>
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The practical consequence: a compile-time check, a code review, or an IDE's autocomplete cannot
tell you that `undo()` needs a Redgate Teams or Enterprise license. Only calling it — or reading
the bytecode this test reads — does. For everyday rollback needs on the Community edition, the
honest options are the ones Flyway's own OSS command set actually supports: write and ship a new,
forward-only migration that reverses the change, or restore from a backup taken before the
migration ran. Both are less elegant than `flyway undo`, and both actually work on the free jar.

## Going deeper

- [Flyway editions comparison](https://www.red-gate.com/products/flyway/editions/) (`rel="nofollow"`) — the vendor's own breakdown of which commands need which tier.
- **This is not a licensing violation to work around.** The stub classes exist so a Community user who calls one of these APIs gets a clear runtime exception naming the required edition, rather than a `NoSuchMethodError` or a silent no-op — it's arguably the more honest of the two ways to gate a feature.
- Liquibase's own commercial/community split works differently — chapter [12](12-the-oss-license-service.md) verifies what actually happens on the Community jar's license-checking path, and it is not a stub-and-throw pattern at all.