Database migration with flyway
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This document discusses using the Flyway tool to manage database schema migrations. Flyway allows defining SQL scripts to update the database schema and records the changes in a schema version table. The document provides instructions on setting up Flyway for a project, running migrations with Flyway, and the process for adding new migrations when making changes to data models.
Database migration with flyway
- 2. What's the problem? Provide upgrades of applications and databases to our customers Some customers require SQL scripts to run via DB admin tools, e.g. Oracle (sqlplus) We don't have database schemas that reflect what's been applied in terms of updates - always the newest We don't really understand what Hibernate is doing to create/modify tables based on our persistent objects, we rely on it for optimization, indexes etc...
- 3. Database Migrations Structure SQL scripts for creation of the schema, updates of the schema accordingly Use a tool to run these migrations: ● In a specific order ● Against a specific database (MySQL, Oracle) ● Recording the actions in a schema version table Lots of tools that do this
- 4. Flyway Allows us to do migrations: ● From a shell script ● Programmatically ● When Spring starts ● Using Maven as a build tool
- 5. Introducing Flyway into your project Has been done for MIF - there's a dbtool folder in the source structure. We can provide a template in SVN that can be used. 1. Download the dbtool structure 2. Generate an export of the schema that Hibernate has created for your project
- 6. Introducing Flyway into your project 3. Tweak/optimise if necessary 4. Run the following command: ./flyway.sh init
- 7. Introducing Flyway into your project This creates the SCHEMA_VERSION table: mysql> desc SCHEMA_VERSION; +-----------------+--------------+------+-----+-------------------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------------+--------------+------+-----+-------------------+-------+ | version | varchar(20) | NO | PRI | NULL | | | description | varchar(100) | YES | | NULL | | | type | varchar(10) | NO | | NULL | | | script | varchar(200) | NO | UNI | NULL | | | checksum | int(11) | YES | | NULL | | | installed_by | varchar(30) | NO | | NULL | | | installed_on | timestamp | NO | | CURRENT_TIMESTAMP | | | execution_time | int(11) | YES | | NULL | | | state | varchar(15) | NO | | NULL | | | current_version | tinyint(1) | NO | MUL | NULL | | +-----------------+--------------+------+-----+-------------------+-------+
- 8. Performing a migration Assume you've added a new script in the <dbname>/sql folder of dbtool Run: ./flyway.sh migrate This will run the script and record the action in the SCHEMA_VERSION table.
- 9. Flyway dbtool structure ├── mysql │ ├── conf │ │ └── flyway.properties │ ├── flyway.cmd │ ├── flyway.sh │ ├── jars │ │ └── mysql-connector-java-5.1.14.jar │ └── sql │ ├── V1__MIFBaseSchema.sql │ └── V2__JOB.DATE_ACKNOWLEDGED.sql └── oracle ├── conf │ └── flyway.properties ├── flyway.cmd ├── flyway.sh ├── jars │ └── ojdbc14-10.2.0.5.jar └── sql
- 10. Process Change Need to change the way we develop persistent objects with Hibernate As well as changing an object we also need to provide a migration script (and a rollback script) Put it in the <dbname>/sql folder. ls -Al mysql/sql V1__MIFBaseSchema.sql V2__JOB.DATE_ACKNOWLEDGED.sql
- 11. Example Change a persistent object to add a new field Write a script with the appropriate ALTER TABLE ADD COLUMN statement. Write the rollback script Test