Using Liquibase with PostgreSQL

PostgreSQL is an open-source, object-relational database system that supports a large part of the SQL standard and offers many modern features:

• complex queries
• foreign keys
• triggers
• updatable views
• transactional integrity
• multiversion concurrency control

For more information, see the PostgreSQL documentation page.

Supported versions

• 15.X
• 14.X
• 13.X
• 12.X
• 11.X
• 10.X
• 9.X

Verification level

Guaranteed: Community and Commercial functionality has been certified by Liquibase via automated and real-world testing.

Note: A database's verification level indicates how well it works with different features in Liquibase and across different products, such as Liquibase Community and Liquibase Pro. For more information, see Liquibase Database Tutorials.

Prerequisites

• Install Liquibase.
• Create a Liquibase project folder to store all Liquibase files. You can do this manually or with the init project command.
• Create a new Liquibase properties file or use the liquibase.properties file included in the installation package. For more information, see Specifying Properties in a Connection Profile.

Install drivers

To use Liquibase and PostgreSQL, you need the JDBC driver JAR file (Maven download).

The latest version of Liquibase has a pre-installed driver for this database in the liquibase/internal/lib directory. Read more: Adding and Updating Liquibase Drivers.

If you use Maven, you must include the driver JAR as a dependency in your pom.xml file. Read more: Configuring Liquibase Attributes in your Maven POM File.

<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.4.0</version>
</dependency>

Also, you can use the Liquibase PostgreSQL Extension JAR file, which is the vacuum extension that adds an additional changelog tag or command to support vacuuming.

Test your connection

1. Ensure PostgreSQL is configured:
• PostgreSQL
• PostgreSQL on AWS RDS
2. Specify the database URL in the Liquibase properties file. Liquibase does not parse the URL. You can either specify the full database connection string or specify the URL using your database's standard JDBC format:
• PostgreSQL
• PostgreSQL on AWS RDS

3. Create a text file called changelog (.xml, .sql, .json, or .yaml) in your project directory and add a changeset.
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"
	xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext"
	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-latest.xsd
		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">
    <changeSet id="1" author="Liquibase">
    <createTable tableName="test_table">
           <column name="test_id" type="int">
                 <constraints primaryKey="true"/>
           </column>
           <column name="test_column" type="varchar"/>
    </createTable>
    </changeSet>
</databaseChangeLog>

SQL example

-- liquibase formatted sql

-- changeset liquibase:1
CREATE TABLE test_table (test_id INT, test_column VARCHAR(256), PRIMARY KEY (test_id))

Tip: Formatted SQL changelogs generated from Liquibase versions before 4.2 might cause issues because of the lack of space after a double dash ( -- ). To fix this, add a space after the double dash. For example: -- liquibase formatted sql instead of --liquibase formatted sql and -- changeset myname:create-table instead of --changeset myname:create-table

YAML example

databaseChangeLog:
   - changeSet:
       id: 1
       author: Liquibase
       changes:
       - createTable:
           columns:
           - column:
               name: test_column
               type: INT
               constraints:  
                   primaryKey:  true  
                   nullable:  false  
                   tableName: test_table

JSON example

{ 
  "databaseChangeLog": [
  {
	"changeSet": {
	  "id": "1",
      "author": "Liquibase",
	  "changes": [
	    {
		  "createTable": {
		    "columns": [
			{
			  "column": 
		      {
				"name": "test_column",
				"type": "INT",
				"constraints": 
			  {
				"primaryKey": true,
				"nullable": false
				}
				}
			  }]
			,
			"tableName": "test_table"
		  }
		}]
	  }
	}]
  }

4. Navigate to your project folder in the CLI and run the Liquibase status command to see whether the connection is successful:

liquibase --username=test --password=test --changelog-file=<changelog.xml> status

Note: You can pass arguments in the CLI or keep them in the Liquibase properties file.

5. Inspect the SQL with the update-sql command. Then make changes to your database with the update command.

liquibase --changelog-file=<changelog.xml> update-sql
liquibase --changelog-file=<changelog.xml> update

6. From a database UI tool, ensure that your database contains the test_table you added along with the DATABASECHANGELOG table and DATABASECHANGELOGLOCK table.

PostgreSQL

• Check the status by running the pg_isready command. For more information about the options you can specify when running the command, see the pg_isready webpage.
• Specify the database URL in the Liquibase properties file, as follows:

url: jdbc:postgresql://<host>:<port>/<dbname>

Tip: To apply a Liquibase Pro key to your project, add the following property to the Liquibase properties file: liquibaseProLicenseKey: <paste code here>

PostgreSQL on AWS RDS

Check the connection by using any standard SQL client application, including the psql command line utility that is part of a PostgreSQL installation, and running the following:

Linux, macOS, or Unix

psql \
--host=<DB instance endpoint> \
--port=<port> \
--username=<master username> \
--password \
--dbname=<database name>

Windows

psql ^
--host=<DB instance endpoint> ^
--port=<port> ^
--username=<master username> ^
--password ^
--dbname=<database name>

Note: If this is the first time you are connecting to your DB instance, you can try using the default database name postgres for the --dbname option.

Tip: The alternative way is to connect with pgAdmin, which is an open-source administration and development tool for PostgreSQL.

You can find the connection information in the AWS Management Console:

1. Sign in to the AWS Management Console and open the Amazon RDS console.
2. In the upper-right corner of the console, choose the AWS Region of your DB instance.
3. Find the host and port for your DB Instance:
   • Select Databases and choose the needed PostgreSQL DB instance to display the instance details.
   • Select Connectivity & security. You will see all information under Endpoint & Port.

Note: To find the connection information using the AWS CLI, call the describe-db-instances command: aws rds describe-db-instances. Alternatively, you can use the Amazon RDS API DescribeDBInstances operation.

Specify the database URL in the Liquibase properties file, as follows:

url: jdbc:postgresql://<instance_host>:<instance_port>/<database_name>?user=userName&password=password

Example: url: jdbc:postgresql://myinstance.123456789012.us-east-1.rds.amazonaws.com:5432/postgresql?user=user&password=password

Related links

• PostgreSQL Documentation
• Getting Started: Using Liquibase with Azure Postgres
• Using Liquibase and AWS RDS
• Connecting to a DB instance running the PostgreSQL database engine
• Liquibase Change Types
• Concepts
• Liquibase Commands
• Workflows
• Using the PSQL integration and runWith attribute with Liquibase Pro and PostgreSQL