Introduction to Liquibase - tool to manage changes in RDBMS.

1. Database change management with
Liquibase
Introduction
Prepared by: Jarosław Szczepankiewicz
Submitted on: 2014-02-11
Version: 1.0
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2. Why should I care about db change management?
Can I quickly setup new instance on DEV / PROD?
What is the state of database on machine X in relation to
application version
Who did last upgrade of db? When?
How can I easily upgrade db to version X
How can i easily downgrade db to version Y
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3. Liquibase promises
Keep changes in special format as portable as possible
between DB versions
Let’s the tool check which changes should be applied to
upgrade the db to specified version
Allow me to rollback changes
Give audit information
Initialize the whole db from the ground
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4. How to start?
Write changes (changesets) in format you like:
XML (with XSD support), YAML, JSON, SQL
Invoke tool
Commandline
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Ant
Maven
Spring / CDI (as part of application lifecycle)

5. Let’s code!
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6. Rollbacks
Most DDL have rollbacks
Insert, drop X not autorollbacked
Can be declared empty (<rollback/>) but watch out!
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7. Parameters
From environment or declared in source
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8. Preconditions (for changesets)
Conditionally execute changeset
AND / OR / NOT available
Custom preconditions available (through interface
implementation)
Dbms, runningAs, changeSetExecuted, columnExists,
tableExists, viewExists, foreignKeyConstraintExists, indexExists,
sequenceExists
On changelog (applied to all files) or changeset level
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9. Custom SQL
Can specify „normal” instruction + rollback
Can be conditionally executed based on dbms type
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10. Not enough refactorings?
Create your own refactoring class and invoke from changeset
(liquibase.change.custom.CustomTaskChange,
liquibase.change.custom.CustomSqlRollback)
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11. Your project has already DB?
Generate changelog / sets from existing db
Not all features supported (triggers, procedures)
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DIFF
Check the difference between databases using content
analysing rather than changelog table history
Not recommended (limited abilities) but sometime usefull
Report mode (list) or changeset mode (*.xml)

13. DBDoc
Document state + history of changelog / db in javalike style
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14. Extensions
Hibernate – analyze db + mapping and generate diff
MS SQL / Oracle / Postgresql extensions
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…

15. Thank you
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