Liquibase migration for data bases
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The document discusses the importance of database migration and the tools used, specifically Liquibase, for managing database schema changes and initial data. It covers the structure of database changes, how Liquibase works with various database types, and the formats supported for changesets and changelogs. Additionally, it outlines recommendations and peculiarities associated with using Liquibase for effective database version control.
![how it works
•Changeslog (JSON){
databaseChangeLog: [
"changeSet": {
"id": "addColumn-example",
"author": "liquibase-docs",
"changes": [
{
"addColumn": {
"catalogName": "cat",
"columns": [
{
"column": {
"name": "address",
"type": "varchar(255)“
}
}]
,
"schemaName": "public",
"tableName": "person"
}
}]
}](https://image.slidesharecdn.com/liquibase-160112185556/85/Liquibase-migration-for-data-bases-15-320.jpg)
![how it works
- Changesets uniquely identified by [Author, ID, File path]
- Liquibase tracks changeset execution in a special table
- Lock table to prevent concurrent Liquibase invocations
- Modified changesets are detected via checksums](https://image.slidesharecdn.com/liquibase-160112185556/85/Liquibase-migration-for-data-bases-16-320.jpg)
![how it works
CLI commands:
update [Count, Tag]
rollback [Count, Data, Tag]
generateChangeLog --diffTypes=tables, views,
columns, indexes, foreignkeys, primarykeys,
uniqueconstraints, data
diff --referenceUrl=<value>
status --verbose
updateSQL ...](https://image.slidesharecdn.com/liquibase-160112185556/85/Liquibase-migration-for-data-bases-18-320.jpg)
Liquibase migration for data bases
- 1. source control for your DB
- 2. why Data Base migration: Data base structure: - Tables, constrains, indexes; Data base data: - Initial data like list of post codes, statuses for order, etc. Data base logic: - stored procedures, triggers, functions
- 3. why Data Base migration: Data base structure: - Tables, constrains, indexes; Data base data: - Initial data like list of post codes, statuses for order, etc. Data base logic: - stored procedures, triggers, functions v1.0.0
- 4. why Data Base migration: Data base structure: - Tables, constrains, indexes; Data base data: - Initial data like list of post codes, statuses for order, etc. Data base logic: - stored procedures, triggers, functions v1.2.1 v1.0.0
- 5. why Data Base migration: Data base structure: - Tables, constrains, indexes; Data base data: - Initial data like list of post codes, statuses for order, etc. Data base logic: - stored procedures, triggers, functions v1.2.1 v1.6.0 v1.0.0
- 6. why Data Base migration: Data base structure: - Tables, constrains, indexes; Data base data: - Initial data like list of post codes, statuses for order, etc. Data base logic: - stored procedures, triggers, functions v1.2.1 v1.6.0 v2.0.1 v1.0.0
- 7. why Data Base migration: Data base structure: - Tables, constrains, indexes; Data base data: - Initial data like list of post codes, statuses for order, etc. Data base logic: - stored procedures, triggers, functions v1.2.1 v1.6.0 v2.0.1 v1.0.0
- 8. What Liquibase : •Apache license •Started in 2006 (active)
- 9. What Liquibase : •Database migration for Java; •Can be used as •Ant, Maven or Gradle plugin, •as CLI tool; • as part of the system : •Servlet Listener •Spring Listener •JEE CDI Listener
- 10. how it works •Supports multiple database types: MySQL, PostgreSQL, Oracle, MsSql, Sybase_Enterprise, Sybase_Anywhere , DB2, Apache_Derby, HSQL, H2, Informix, Firebird, SQLite
- 11. how it works Changes are grouped into changesets: • Change(s) that should be applied atomically Changesets are grouped into changelogs: •Files managed in version control
- 12. how it works Supports XML, YAML, JSON (DSL for database changes) and SQL formats: •Create Table, Add PK, Add FK, Add Column, Add Index, … •Drop Table, Drop PK, Drop FK, Drop Column, Drop Index, … •Insert, Update, Delete, …
- 13. how it works •Changeslog (XML): <databaseChangeLog xmlns=…> <changeSet author="liquibase-docs“ id="addColumn-example"> <addColumn catalogName="cat“ schemaName="public" tableName="person"> <column name="address" type="varchar(255)"/> </addColumn> </changeSet> <changeSet> ….</changeset> <changeSet> ….</changeset> </databaseChangeLog>
- 14. how it works •Changeslog (YAML): databaseChangeLog: changeSet: id: addColumn-example author: liquibase-docs changes: - addColumn: catalogName: cat columns: - column: name: address type: varchar(255) schemaName: public tableName: person
- 15. how it works •Changeslog (JSON){ databaseChangeLog: [ "changeSet": { "id": "addColumn-example", "author": "liquibase-docs", "changes": [ { "addColumn": { "catalogName": "cat", "columns": [ { "column": { "name": "address", "type": "varchar(255)“ } }] , "schemaName": "public", "tableName": "person" } }] }
- 16. how it works - Changesets uniquely identified by [Author, ID, File path] - Liquibase tracks changeset execution in a special table - Lock table to prevent concurrent Liquibase invocations - Modified changesets are detected via checksums
- 18. how it works CLI commands: update [Count, Tag] rollback [Count, Data, Tag] generateChangeLog --diffTypes=tables, views, columns, indexes, foreignkeys, primarykeys, uniqueconstraints, data diff --referenceUrl=<value> status --verbose updateSQL ...
- 19. let us try it DDLv1
- 20. DDL v2 v1 Init data, new column (source) let us try it
- 21. how it works DDL v2 v3 v1 Init data, new column (source) Move values in separate table let us try it
- 22. let us try it DDL v2 v3 v1 Init data, new column (source) Move values in separate table
- 24. how it works Spring config (embedded in your application): <dependency> <groupId>org.liquibase</groupId> <artifactId>liquibase-core</artifactId> <version>${liquibase.version}</version> </dependency> <bean id="liquibase" class="liquibase.integration.spring.SpringLiquibase"> <property name="dataSource" ref="myDataSource" /> <property name="changeLog" value="classpath:db-changelog.xml" /> <!-- contexts specifies the runtime contexts to use. --> <property name="contexts" value="test, production" /> </bean>
- 25. how it works Spring Boot config (embedded in your application ): <dependency> <groupId>org.liquibase</groupId> <artifactId>liquibase-core</artifactId> <version>${liquibase.version}</version> </dependency> none https://github.com/spring-projects/spring-boot/tree/master/spring-boot-samples/spring-boot-sample-liquibase
- 26. how it works •Also: <changeSet id="4" dbms="oracle"> <sqlFile path="5.sql"/> </changeSet> <changeSet id="5" context="test"> <sqlFile path="5.sql"/> </changeSet> <changeSet id="6" failOnError="false"> <sqlFile path="6.sql"/> </changeSet>
- 27. how it works •Also: <preConditions> <dbms type="oracle" /> <runningAs username="SYSTEM" /> </preConditions> <changeSet id="1" author="bob"> <preConditions onFail="WARN"> <sqlCheck expectedResult="0"> select count(*) from oldtable </sqlCheck> </preConditions> <comment>Comments should go after preCondition. If they are before then liquibase usually gives error.</comment> <dropTable tableName="oldtable"/> </changeSet>
- 28. recommendations • it is better to have each change in separate changes ; • Document changesets with <comment> tag; • Folders structure should reflect migration structure com example db changelog db.changelog-master.xml db.changelog-1.0.xml db.changelog-1.1.xml db.changelog-2.0.xml
- 29. peculiarities •if you do roll back, Liquibase deletes the log line about the update from databasechangelog table, and after that Liguibase does not know any more that this change was applied and reverted; •all changes are applied sequentially, so we can not apply/rollback separate mediate changes; •no straightforward way of customizing warn/error messages;
- 30. peculiarities •Each change set has an “id” and “author” attribute which, along with the directory and file name of the the change log file, uniquely identifies it. Dark side of it is that running the same change set using relative and absolute path will be considered as different changesets! For example we have file /home/user/changelog-0.1.0.xml First we execute: $ liquibase --changeLogFile=/home/user/changelog-0.1.0.xml and then if we try to execute $ liquibase --changeLogFile=changelog-0.1.0.xml
- 31. The end Thank you for attention Q & A r.uholnikov@levi9.com