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Get started with Liquibase and Neon

Summary: Connect Liquibase to a Lakebase Postgres database over JDBC to track, deploy, and roll back versioned schema changes defined in XML changelog files. Use this guide when you need to version-control DDL changes against Neon with a repeatable deploy-and-rollback workflow. Covers the liquibase.properties JDBC URL format for Neon and demonstrates the update and rollbackCount commands.

Get started with Liquibase and Neon

Section titled “Get started with Liquibase and Neon”

Learn how to manage schema changes in Neon with Liquibase

Liquibase is an open-source library for tracking, managing, and applying database schema changes. To learn more about Liquibase, refer to the Liquibase documentation.

This guide steps you through installing the Liquibase CLI, configuring Liquibase to connect to a Lakebase Postgres database, deploying a database schema change, and rolling back the schema change. The guide follows the setup described in the Liquibase Get Started.

Prerequisites

Section titled “Prerequisites”
  • A Neon account. See Sign up.
  • A Neon project. See Create your first project.
  • Liquibase requires Java. For Liquibase Java requirements, see Requirements. To check if you have Java installed, run java --version, or java -version on macOS.

Download and extract Liquibase

Section titled “Download and extract Liquibase”

  1. Download the Liquibase CLI from https://www.liquibase.com/download.

  2. Extract the Liquibase files. For example:

    Bash
    cd ~/Downloads
mkdir ~/liquibase
tar -xzvf liquibase-x.yy.z.tar.gz -C ~/liquibase/

  3. Open a command prompt to view the contents of your Liquibase installation:

    Bash
    cd ~/liquibase
ls
ABOUT.txt      GETTING_STARTED.txt  licenses     liquibase.bat
changelog.txt  internal             LICENSE.txt  README.txt
examples       lib                  liquibase    UNINSTALL.txt

Set your path variable

Section titled “Set your path variable”

Add the Liquibase directory to your PATH so that you can run Liquibase commands from any location.

bashrc

Bash
echo 'export PATH=$PATH:/path/to/liquibase' >> ~/.bashrc
source ~/.bashrc

profile

Bash
echo 'export PATH=$PATH:/path/to/liquibase' >> ~/.profile
source ~/.profile

zsh

Bash
echo 'export PATH=$PATH:/path/to/liquibase' >> ~/.zshrc
source ~/.zshrc

Verify your installation

Section titled “Verify your installation”

Verify that the Liquibase installation was successful by running the following command:

Bash
liquibase --version
...
Liquibase Version: x.yy.z
Liquibase Open Source x.yy.z by Liquibase

Prepare a Neon database

Section titled “Prepare a Neon database”

For demonstration purposes, create a blog database in Neon with two tables, posts and authors.

  1. Open the Neon Console.

  2. Select your project.

  3. Select Postgres database > Databases from the sidebar and create a database named blog. For instructions, see Create a database.

  4. Using the Neon SQL Editor, add the following tables:

    SQL
    -- Creating the `authors` table
CREATE TABLE authors (
    author_id SERIAL PRIMARY KEY,
    first_name VARCHAR(100),
    last_name VARCHAR(100),
    email VARCHAR(255) UNIQUE NOT NULL,
    bio TEXT
);

-- Creating the `posts` table
CREATE TABLE posts (
    post_id SERIAL PRIMARY KEY,
    author_id INTEGER REFERENCES authors(author_id),
    title VARCHAR(255) NOT NULL,
    content TEXT,
    published_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Retrieve your Neon database connection string

Section titled “Retrieve your Neon database connection string”

Find your database connection string by clicking the Connect button in the Console nav to open the Connect to your branch modal. Use the selection drop-down menu.

Your Java connection string should look something like the one shown below.

Bash
jdbc:postgresql://ep-cool-darkness-123456.us-east-2.aws.neon.tech/blog?user=alex&password=AbC123dEf

Important: Use a direct (non-pooled) connection string with Liquibase. Neon's pooled connection uses PgBouncer in transaction mode, which doesn't support all session-level operations that schema migration tools rely on, so running migrations over a pooled connection can lead to errors. Make sure the hostname does not include the -pooler suffix (turn the Connection pooling toggle off in the Connect modal). See Connection pooling.

Connect from Liquibase to your Neon database

Section titled “Connect from Liquibase to your Neon database”

  1. Create a directory for your Liquibase project. For example:

    Bash
    mkdir blogdb

  2. Change to your project directory and create a liquibase.properties file.

    Bash
    cd blogdb
touch liquibase.properties

  3. Open the liquibase.properties file in an editor and add entries for a liquibase changelog file and your database url. We'll call the changelog file dbchangelog.xml. You will use this file to define schema changes. For the url, specify the Neon connection string you retrieved previously.

    Bash
    changeLogFile:dbchangelog.xml
url: jdbc:postgresql://ep-cool-darkness-123456.us-east-2.aws.neon.tech/blog?user=alex&password=AbC123dEf&sslmode=require&channel_binding=require

Take a snapshot of your database

Section titled “Take a snapshot of your database”

In this step, you will run the generateChangelog command in your project directory to create a changelog file with the current state of your database. We'll call this file mydatabase_changelog.xml.

Bash
liquibase --changeLogFile=mydatabase_changelog.xml generateChangeLog

You'll get a changelog file for your database that looks something like this:

xml
<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
    <changeSet author="alex (generated)" id="1697969580160-1">
        <createTable tableName="authors">
            <column autoIncrement="true" name="author_id" type="INTEGER">
                <constraints nullable="false" primaryKey="true" primaryKeyName="authors_pkey"/>
            </column>
            <column name="first_name" type="VARCHAR(100)"/>
            <column name="last_name" type="VARCHAR(100)"/>
            <column name="email" type="VARCHAR(255)">
                <constraints nullable="false"/>
            </column>
            <column name="bio" type="TEXT"/>
        </createTable>
    </changeSet>
    <changeSet author="alex (generated)" id="1697969580160-2">
        <createTable tableName="posts">
            <column autoIncrement="true" name="post_id" type="INTEGER">
                <constraints nullable="false" primaryKey="true" primaryKeyName="posts_pkey"/>
            </column>
            <column name="author_id" type="INTEGER"/>
            <column name="title" type="VARCHAR(255)">
                <constraints nullable="false"/>
            </column>
            <column name="content" type="TEXT"/>
            <column defaultValueComputed="CURRENT_TIMESTAMP" name="published_date" type="TIMESTAMP WITHOUT TIME ZONE"/>
        </createTable>
    </changeSet>
    <changeSet author="alex (generated)" id="1697969580160-3">
        <addUniqueConstraint columnNames="email" constraintName="authors_email_key" tableName="authors"/>
    </changeSet>
    <changeSet author="alex (generated)" id="1697969580160-4">
        <addForeignKeyConstraint baseColumnNames="author_id" baseTableName="posts" constraintName="posts_author_id_fkey" deferrable="false" initiallyDeferred="false" onDelete="NO ACTION" onUpdate="NO ACTION" referencedColumnNames="author_id" referencedTableName="authors" validate="true"/>
    </changeSet>
</databaseChangeLog>

Create a schema change

Section titled “Create a schema change”

Now, you can start making database schema changes by creating changesets and adding them to the database changelog file you defined in your liquibase.properties file. A changeset is the basic unit of change in Liquibase.

  1. Create the changelog file where you will add your schema changes:

    Bash
    cd ~/blogdb
touch dbchangelog.xml

  2. Add the following changeset, which adds a comments table to your database. Replace author="alex" id="myIDNumber1234" with your author name and id, which you can retrieve from your changelog file, described in the previous step.

    xml
    <?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"
xmlns:pro="http://www.liquibase.org/xml/ns/pro"
xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.4.xsd
    http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-4.5.xsd">
    <changeSet author="alex" id="myIDNumber1234">
        <createTable tableName="comments">
            <column autoIncrement="true" name="comment_id" type="INTEGER">
                <constraints nullable="false" primaryKey="true" primaryKeyName="comments_pkey"/>
            </column>
            <column name="post_id" type="INTEGER">
                <constraints nullable="false" foreignKeyName="fk_comments_post_id" referencedTableName="posts" referencedColumnNames="post_id"/>
            </column>
            <column name="author_id" type="INTEGER">
                <constraints nullable="false" foreignKeyName="fk_comments_author_id" referencedTableName="authors" referencedColumnNames="author_id"/>
            </column>
            <column name="comment" type="TEXT"/>
            <column name="commented_date" type="TIMESTAMP" defaultValueComputed="CURRENT_TIMESTAMP"/>
        </createTable>
    </changeSet>
</databaseChangeLog>

Deploy your change

Section titled “Deploy your change”

Deploy your database schema change by running the update command:

Bash
liquibase update
Command output

If the command was successful, you'll see output similar to the following:

Bash
Starting Liquibase at 07:33:53 (version 4.24.0 #14062 built at 2023-09-28 12:18+0000)
Liquibase Version: 4.24.0
Liquibase Open Source 4.24.0 by Liquibase
Running Changeset: dbchangelog.xml::myIDNumber1234::AlexL

UPDATE SUMMARY
Run:                          1
Previously run:               0
Filtered out:                 0
-------------------------------
Total change sets:            1

Liquibase: Update has been successful. Rows affected: 1
Liquibase command 'update' was executed successfully.

Info:

When you run a changeset for the first time, Liquibase automatically creates two tracking tables in your database:

You can verify these tables were created by viewing the blog database on the Tables page in the Neon Console. Select Postgres database > Tables from the sidebar.

Rollback a change

Section titled “Rollback a change”

Try rolling back your last change by running the Liquibase rollbackCount command:

Bash
liquibase rollbackCount 1
Command output

If the command was successful, you'll see output similar to the following:

Bash
Starting Liquibase at 07:36:22 (version 4.24.0 #14062 built at 2023-09-28 12:18+0000)
Liquibase Version: 4.24.0
Liquibase Open Source 4.24.0 by Liquibase
Rolling Back Changeset: dbchangelog.xml::myIDNumber1234::AlexL
Liquibase command 'rollbackCount' was executed successfully.

You can verify that creation of the comments table was rolled back viewing the blog database on the Tables page in the Neon Console. Select Postgres database > Tables from the sidebar.

Next steps

Section titled “Next steps”

Learn how to use Liquibase with Neon's database branching feature to set up a developer workflow. See Set up a developer workflow with Liquibase and Neon.

References

Section titled “References”
Section titled “Related docs (Schema Migration)”

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