The document discusses database versioning using FlywayDB. It describes how FlywayDB works by maintaining a metadata table to track the current schema version and searching the classpath for SQL or Java-based migration files sorted by version number. Migrations are applied in order to bring the database schema to the desired state. The document also covers executing FlywayDB via the command line, Maven, Ant, Gradle or API and provides examples of migration file naming conventions and syntax.

1. Database versioning
with FlywayDB
Manuel de la Peña
Software Engineer
@mdelapenya

2. Why DB migration tools?

3. Why DB migration tools?
Lots of developers!!!

4. Why DB migration tools?
https://cdn1.iconfinder.com/data/icons/database/PNG/256/Database_3.png
CI
Test
Development
Pre
Pro
Lots of developers!!!

5. …in the code side…
Version Control
Release tool/plugins on CI

6. …but in the Database…

11. Which version is your DB?

13. What we’d love is…

14. What we’d love is…
Recreate DB from scratch
Make it clear the state of the DB
Migrate in a deterministic way!!

15. Database migrations
Made easy

16. How FlywayDB works

17. How FlywayDB works
Metadata table (SCHEMA_VERSION)

18. How FlywayDB works
Metadata table (SCHEMA_VERSION)
Classpath search for migrations

19. How FlywayDB works
Metadata table (SCHEMA_VERSION)
Classpath search for migrations
SQL or Java

20. How FlywayDB works
Metadata table (SCHEMA_VERSION)
Classpath search for migrations
SQL or Java
Sorted by version, and applied in order

21. How FlywayDB works
Metadata table (SCHEMA_VERSION)
Classpath search for migrations
SQL or Java
Compared against current version
Sorted by version, and applied in order

22. How FlywayDB works
Metadata table (SCHEMA_VERSION)
Classpath search for migrations
SQL or Java
Compared against current version
Sorted by version, and applied in order
Checksum change-detection validation

23. Supported DB’s
Oracle
SQL Server
SQL Azure
DB2MySQL
MariaDB
Google Cloud SQL
PostgreSQL
H2
HSQL
Derby Android SQLite

24. Executing FlywayDB
Command Line

25. Executing FlywayDB
Command Line
flyway.properties
jars dir
migrations dir
flyway migrate

26. Executing FlywayDB
Command Line
Maven Plugin

27. Executing FlywayDB
Command Line
Maven Plugin
Ant

28. Executing FlywayDB
Command Line
Maven Plugin
Ant
Gradle

29. Executing FlywayDB
Command Line
Maven Plugin
Ant
Gradle
SBT (Scala Build Tool)

30. Executing FlywayDB
Command Line
Maven Plugin
Ant
Gradle
SBT (Scala Build Tool)
API
Java classes
Spring configuration

31. Migrations

32. Versions
One 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

33. 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

34. SQL Migrations

35. Discovery

36. Discovery
Filesystem locationClasspath location
Automatically at runtime

37. Naming
prefix: Configurable, default: V
version: Dots or underscores separate the parts,
as many parts as you like
separator: Configurable, default: __ (2 underscores)
description: Underscores or spaces to separate
the words
suffix: Configurable, default: .sql

38. Sample SQL versions
V_1__Add_phone_number_to_user.sql
V_2__Remove_picture_to_user.sql
V_3__Add_folders_to_article.sql

39. Syntax

40. Syntax
Single/multiline statements
Single/multiline comments
Placeholder replacements
DB specific extensions

41. Java Migrations

42. ¿Java migrations?

43. ¿Java migrations?
C/LOB changes
Advanced Bulk data operations

44. Discovery
flyway.setLocations(…)

45. Naming
prefix: Always V
version: Underscores separate the parts, as many
parts as you like
separator: __ (2 underscores)
description: Underscores to separate the words

46. Sample Java versions
V_1__Add_phone_number_to_user.java
V_2__Remove_picture_to_user.java
V_3__Add_folders_to_article.java

47. Usage

48. Usage
Implements JdbcMigration
Wraps the migration in a transaction
Extracts the version from class name

49. Advanced usage

50. Advanced usage
MigrationProviderInfo:
redefine prefix, version, separator...

51. Advanced usage
MigrationProviderInfo:
redefine prefix, version, separator...
MigrationChecksumProvider:
getChecksum()

52. Advanced usage
MigrationProviderInfo:
redefine prefix, version, separator...
MigrationChecksumProvider:
getChecksum()
Spring support:
implements SpringJdbcMigration
(JdbcTemplate)

53. Migrating existing databases

54. Steps
1. 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

55. More advanced usage

56. Advanced usage
OSGi support
Cluster migrations in parallel
Multiple schema support
Placeholder replacements ${placeholder}
Before-Hibernate-Export integration

57. Drawbacks

58. Drawbacks
Rollback migrations with destructive changes
Initial schema not retrieved from existing
database
DB-specific code must be separated by locations

59. FlywayDB
Demo

60. Thank you!
Questions?