SQL Upgrade Scripts

The database schema for the Dataverse Software is constantly evolving and we have adopted a tool called Flyway to help keep your development environment up to date and in working order. As you make changes to the database schema (changes to @Entity classes), you must write SQL upgrade scripts when needed and follow Flyway file naming conventions.

Location of SQL Upgrade Scripts

src/main/resources/db/migration is the directory where we keep SQL upgrade scripts for Flyway to find.

In the past (before adopting Flyway) we used to keep SQL upgrade scripts in scripts/database/upgrades. These scripts can still be used as reference but no new scripts should be added there.

How to Determine if You Need to Create a SQL Upgrade Script

If you are creating a new database table (which maps to an @Entity in JPA), you do not need to create or update a SQL upgrade script. The reason for this is that we use create-tables in src/main/resources/META-INF/persistence.xml so that new tables are automatically created by the app server when you deploy your war file.

If you are doing anything other than creating a new database table such as adding a column to an existing table, you must create or update a SQL upgrade script.

How to Create a SQL Upgrade Script

We assume you have already read the Version Control section and have been keeping your feature branch up to date with the “develop” branch.

Create a new SQL file in the src/main/resources/db/migration directory and put a short, meaningful comment at the top. Make the filename something like V6.1.0.1.sql. In this example 6.1 represents the current version of Dataverse, with the last digit representing number of the script for that version. (The zero in this example is a placeholder in case the current version has a third number like 6.1.1.) Should a newer version be merged while you work on your pull request (PR), you must update your script to the next available number such as V6.1.0.2.sql.

Previously, we used longer, more descriptive file naming conventions supported by Flyway. However, this approach occasionally led to inadvertent merging of multiple scripts with the same version, such as V6.0.0.1__0000-wonderful-pr.sql and V6.0.0.1__0001-lovely-pr.sql where V6.0.0.1 must be unique. After careful consideration, we agreed to adopt the convention mentioned above for naming files. This helps us detect conflicts before merging a PR, preventing the develop branch from being undeployable due to a Flyway conflict. For more information on Flyway file naming conventions, see https://documentation.red-gate.com/fd/migrations-184127470.html

The SQL migration script you wrote will be part of the war file and executed when the war file is deployed. To see a history of Flyway database migrations that have been applied, look at the flyway_schema_history table.

As with any task related to the development of the Dataverse Software, if you need any help writing SQL upgrade scripts, please reach out using any of the channels mentioned under “Getting Help” in the Introduction section.


Renaming SQL Upgrade Scripts

Please note that if you need to rename your script (because a new version of the Dataverse Software was released, for example), you will see the error “FlywayException: Validate failed: Detected applied migration not resolved locally” when you attempt to deploy and deployment will fail.

To resolve this problem, delete the old migration from the flyway_schema_history table and attempt to redeploy.