Flywaydb

Database versioning with FlywayDBManuel de la Peña Software Engineer @mdelapenya

Why DB migration tools?


Lots of developers!!!


https://cdn1.iconfinder.com/data/icons/database/PNG/256/Database_3.png

CI

Test

Development

Pre

Pro

Lots of developers!!!

…in the code side…

Version Control

Release tool/plugins on CI

…but in the Database…

Which version is your DB?

What we’d love is…

What we’d love is…

Recreate DB from scratch

Make it clear the state of the DB

Migrate in a deterministic way!!

Database migrationsMade easy

How FlywayDB works

How FlywayDB worksMetadata table (SCHEMA_VERSION)

How FlywayDB worksMetadata table (SCHEMA_VERSION)Classpath search for migrations


SQL or Java


SQL or JavaSorted by version, and applied in order


SQL or Java

Compared against current versionSorted by version, and applied in order


SQL or Java

Compared against current versionSorted by version, and applied in order

Checksum change-detection validation

Supported DB’sOracle

SQL ServerSQL Azure

DB2MySQLMariaDB

Google Cloud SQL

PostgreSQL

H2

HSQL

Derby Android SQLite

Executing FlywayDBCommand Line

Executing FlywayDBCommand Line flyway.properties

jars dirmigrations dirflyway migrate


Maven Plugin


Maven Plugin

Ant


Maven Plugin

Ant

Gradle


Maven Plugin

Ant

Gradle

SBT (Scala Build Tool)


Maven Plugin

Ant

Gradle

SBT (Scala Build Tool)

API Java classesSpring configuration

Migrations

VersionsOne or more numeric parts

Separated by a dots or an underscore

Underscores are replaced by dots at runtime

Leading zeros are ignored on each part

Version examples

1

001

5.2

5_2 (5.2 at runtime)

205.68

1.2.3.4.5.6.7.8.9

20130115113556

2013.1.15.11.35.56

2013.01.15.11.35.56

SQL Migrations

Discovery

Discovery

Filesystem locationClasspath location

Automatically at runtime

Namingprefix: Configurable, default: Vversion: Dots or underscores separate the parts, as many parts as you likeseparator: Configurable, default: __ (2 underscores)description: Underscores or spaces to separate the wordssuffix: Configurable, default: .sql

Sample SQL versions

V_1__Add_phone_number_to_user.sqlV_2__Remove_picture_to_user.sqlV_3__Add_folders_to_article.sql

Syntax

SyntaxSingle/multiline statements

Single/multiline comments

Placeholder replacements

DB specific extensions

Java Migrations

¿Java migrations?

¿Java migrations?

C/LOB changes

Advanced Bulk data operations

Discovery

flyway.setLocations(…)

Namingprefix: Always Vversion: Underscores separate the parts, as many parts as you likeseparator: __ (2 underscores)description: Underscores to separate the words

Sample Java versions

V_1__Add_phone_number_to_user.javaV_2__Remove_picture_to_user.javaV_3__Add_folders_to_article.java

Usage

UsageImplements JdbcMigration

Wraps the migration in a transaction

Extracts the version from class name

Advanced usage

Advanced usageMigrationProviderInfo:

redefine prefix, version, separator...



MigrationChecksumProvider: getChecksum()



MigrationChecksumProvider: getChecksum()

Spring support: implements SpringJdbcMigration

(JdbcTemplate)

Migrating existing databases

Steps1. Take a DDL from production 2. Add inserts for all reference data you need 3. Give relevant version number

(V1__Base-.version.sql) 4. Clean all databases 5. Remove their contents with flyway:clean 6. Align databases with production 7. Exactly the same DDL 8. The objects they migrate must be identical to

what is present in production. 9. Give databases initial version

More advanced usage

Advanced usageOSGi support

Cluster migrations in parallel

Multiple schema support

Placeholder replacements ${placeholder}

Before-Hibernate-Export integration

Drawbacks

Drawbacks

Rollback migrations with destructive changes

Initial schema not retrieved from existing database

DB-specific code must be separated by locations

FlywayDBDemo

Thank you!Questions?

Flywaydb

Technology