asmhatreandClaude Sonnet 5
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Companion code for the Flyway vs Liquibase article: checksum validation, out-of-order and repeatable migrations, baselining an existing schema, Flyway Community's undo/diff/deploy stubs, concurrent-startup locking for both tools, Liquibase changeset identity and rollback (auto-generated vs explicit), a verified Liquibase 5.0.3 filename-caching defect, the new OSS license service, the FSL license change, and running both tools against one database. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01Q6XdRjtsp4862EM44T7i9a
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9. Liquibase: anatomy of an update
← 8. Concurrent startup and locking · Index · Next: 10. Rollback: auto-generated vs explicit →
Liquibase's unit of change is a changeset inside a changelog — one YAML (or XML, or JSON,
or SQL) document listing every change in order, rather than one file per change. This module's
main changelog is
db.changelog-master.yaml;
LiquibaseHappyPathTest
uses a small inline one — a createTable changeset, then an insert changeset — run through the
classic Liquibase
facade directly, with no Spring involved, so the mechanics are visible without an application
context in the way.
databasechangelog:
ID | AUTHOR | FILENAME | ORDEREXECUTED | EXECTYPE
-----------------+--------+-------------+---------------+---------
1-create-account | ankurm | master.yaml | 1 | EXECUTED
2-seed-account | ankurm | master.yaml | 2 | EXECUTED
account table:
ID | OWNER
---+------------------
1 | Katherine Johnson
(from docs/output/09-liquibase-happy-path.txt)
DATABASECHANGELOG is Liquibase's equivalent of flyway_schema_history, but the identity of a
changeset is different in kind from Flyway's version numbers: it's the triple of id, author,
and the changelog filename it was declared in. Two changesets with the same id in two
different files are different changesets to Liquibase; the same id twice in the same file
is a configuration error. There is no numeric ordering at all — order comes purely from position
in the changelog, top to bottom.
Going deeper
update()and the newer command-framework path. Liquibase 5's classicLiquibase.update(...)facade internally delegates to aCommandScope/UpdateCommandStepimplementation rather than the older direct-execution path — visible in every stack trace in this module (chapter 11 has a full one). It doesn't change behaviour for straightforward changesets, but it's worth knowing when a stack trace looks unfamiliar next to older Liquibase tutorials.- Liquibase changelog structure (
rel="nofollow") — the full list of supported changelog formats and the changeset identity rules referenced above. - Liquibase also supports preconditions and contexts/labels for conditionally running changesets — out of scope for this module, but the natural next thing to read once changesets and changelogs make sense.