FOLIO Liquibase Migration Guidelines

1. Folder Structure

Preferred Layout

The preferred structure is versioned — each release gets its own folder and aggregator file:

src/main/resources/db/changelog/
├── changelog-master.xml
└── changes/
    ├── changelog-v1.0.xml
    ├── v1.0/
    │   ├── create-table-foo.xml
    │   └── add-index-foo-bar.xml
    ├── changelog-v2.0.xml
    └── v2.0/
        └── alter-table-foo-add-column-baz.xml

Preferred structure rules:

• changelog-master.xml includes only version aggregators (changes/changelog-vX.Y.xml)
• Each changelog-vX.Y.xml includes only files from changes/vX.Y/
• Create a new vX.Y/ directory and changelog-vX.Y.xml for each module release
• All <include> elements use relativeToChangelogFile="true"

changelog-master.xml example:

<?xml version="1.0" encoding="UTF-8"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
                   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                   xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
                   https://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">

  <include file="/changes/changelog-v1.0.xml" relativeToChangelogFile="true"/>
  <include file="/changes/changelog-v2.0.xml" relativeToChangelogFile="true"/>
</databaseChangeLog>

changes/changelog-v2.0.xml example:

<databaseChangeLog ...>
  <include file="/changes/v2.0/create-table-foo.xml" relativeToChangelogFile="true"/>
  <include file="/changes/v2.0/alter-table-foo-add-column-bar.xml" relativeToChangelogFile="true"/>
</databaseChangeLog>

Working with Existing Modules

Before creating new files, check the existing changelog structure in the module. Always follow the layout already in use — do not reorganize or introduce a different structure mid-project.

• If the module uses changelog-master.xml with per-version aggregators → follow that pattern
• If the module uses a flat changelog-master.xml with direct <include> entries → continue adding entries directly there
• If the module uses different naming or nesting → match what is already there

When starting a brand new module with no existing migrations, use the preferred structure above.

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2. Changeset ID Naming Convention

Format

<JIRA-TICKET>@@<scope>-<action>-<target>[-<detail>]

Allowed Values

Part	Values
scope	schema, data, refactor, fix
action	create, alter, drop, rename, migrate, backfill, seed, cleanup, enforce
target	table-<name>, column-<table>-<col>, index-<name>, fk-<from>-to-<to>, type-<name>
detail	(optional) specific intent, e.g. add-not-null, add-metadata-fields

Style Rules

• Lowercase only
• Kebab-case only (no underscores, no spaces)
• ASCII only — no : characters
• Use imperative verbs (not gerunds or past tense)
• IDs are immutable after release — never rename a released changeset ID

✅ Good Examples

MYMOD-101@@schema-create-table-item
MYMOD-102@@schema-alter-table-item-add-column-status
MYMOD-103@@schema-create-index-item-status
MYMOD-104@@schema-create-fk-item-to-location
MYMOD-105@@data-seed-item-default-status
MYMOD-106@@data-migrate-rule-to-specification-rule-metadata-fields
MYMOD-107@@schema-enforce-column-item-id-not-null
MYMOD-108@@schema-create-type-status-enum

❌ Bad Examples

MYMOD-101@@CreateItemTable          # PascalCase, no scope/action
MYMOD-101@@schema:create:table      # colons not allowed
MYMOD-101@@schema-creating-table    # gerund
MYMOD-101@@schema-created-table     # past tense
item-table                          # missing JIRA ticket and @@

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3. Changeset Structure

Every changeset must include:

1. <comment> — describes what the changeset does and why

<changeSet id="MYMOD-42@@schema-create-table-item" author="john_doe">
  <comment>Create item table for inventory storage</comment>

  <createTable tableName="item">
    ...
  </createTable>
</changeSet>

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4. FOLIO Standard Column Types

Use these types consistently across all FOLIO modules:

Purpose	Type
Primary key / foreign key (UUID)	uuid
Short string	varchar(36) – varchar(250)
Long string	varchar(2500) or text
JSON blob	jsonb
Timestamp	datetime
Boolean flag	bool
Version counter (optimistic locking)	integer
Single character code	char

Metadata Columns

Before adding metadata columns to a new table, ask the user whether they are needed. Not all tables require audit tracking.

If the user confirms, include:

<column name="created_date" type="DATETIME">
  <constraints nullable="false"/>
</column>
<column name="updated_date" type="DATETIME">
  <constraints nullable="false"/>
</column>
<column name="created_by_user_id" type="uuid">
  <constraints nullable="false"/>
</column>
<column name="updated_by_user_id" type="uuid">
  <constraints nullable="false"/>
</column>

---

5. Common Change Patterns

Create Table

<changeSet id="MYMOD-10@@schema-create-table-item" author="jane_doe">
  <comment>Create item table</comment>

  <createTable tableName="item">
    <column name="id" type="UUID">
      <constraints nullable="false" primaryKey="true" primaryKeyName="pk_item"/>
    </column>
    <column name="barcode" type="varchar(250)"/>
    <column name="status" type="varchar(36)">
      <constraints nullable="false"/>
    </column>
    <column name="data" type="jsonb"/>
    <column name="_version" type="integer"/>
    <column name="created_date" type="DATETIME"><constraints nullable="false"/></column>
    <column name="updated_date" type="DATETIME"><constraints nullable="false"/></column>
    <column name="created_by_user_id" type="uuid"><constraints nullable="false"/></column>
    <column name="updated_by_user_id" type="uuid"><constraints nullable="false"/></column>
  </createTable>
</changeSet>

Add Foreign Key

<changeSet id="MYMOD-10@@schema-create-fk-item-to-location" author="jane_doe">
  <comment>Add FK from item to location</comment>

  <addForeignKeyConstraint
    baseTableName="item"
    baseColumnNames="location_id"
    referencedTableName="location"
    referencedColumnNames="id"
    constraintName="fk_item_location_id"/>
</changeSet>

Create Index

<changeSet id="MYMOD-11@@schema-create-index-item-status" author="jane_doe">
  <comment>Create B-tree index on item.status for lookup performance</comment>

  <createIndex tableName="item" indexName="idx_item_status">
    <column name="status"/>
  </createIndex>
</changeSet>

Add Column

<changeSet id="MYMOD-15@@schema-alter-table-item-add-column-effective-location-id" author="jane_doe">
  <comment>Add effective_location_id column to item table</comment>

  <addColumn tableName="item">
    <column name="effective_location_id" type="UUID"/>
  </addColumn>
</changeSet>

Data Migration / Seed

<changeSet id="MYMOD-20@@data-seed-item-default-status" author="jane_doe">
  <comment>Set default status 'Available' for items with null status</comment>

  <sql>
    UPDATE item
    SET status = 'Available'
    WHERE status IS NULL;
  </sql>
</changeSet>

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6. Anti-Patterns to Avoid

❌ Missing comment — no context for reviewers or future developers

<!-- BAD -->
<changeSet id="MYMOD-2@@schema-alter-table-item-add-column-bar" author="foo">
  <addColumn tableName="item">...</addColumn>
</changeSet>

❌ Renaming a released changeset ID — breaks Liquibase checksum validation in all deployed environments

❌ Multiple unrelated changes in one changeset — makes rollback and debugging harder; one logical change per changeset

❌ Using runOnChange="true" on schema changesets — only acceptable for stored procedures/views, never for DDL