diff command

The diff command in Liquibase allows you to compare two databases of the same type, or different types, to one another.

Uses

The diff command is typically used at the completion of a project to verify all expected changes are in the changelog or to detect drift between a model schema and a database's actual schema. The diff command is also useful for the following tasks:

  • Finding missing objects between one database and another
  • Seeing that a change was made to your database
  • Finding unexpected items in your database

Running the diff command

Running the diff command requires two URLs:

  • referenceURL – the source for the comparison. The referenceURL attribute represents your source database which is the starting point and the basis for the database you want to compare.

  • url – the target of the comparison. The URL attribute stands for your target database which you want to compare to the source database. You typically perform actions and run the commands against this database

To compare two databases:

  • The first option is to run the diff command and pass the parameters needed for your source database and target database. You can do this by running the following:
liquibase
--outputFile=mydiff.txt
--driver=oracle.jdbc.OracleDriver
--classpath=ojdbc14.jar
--url="jdbc:oracle:thin:@<IP OR HOSTNAME>:<PORT>:<SERVICE NAME OR SID>"
--username=<USERNAME>
--password=<PASSWORD>
--referenceUrl="jdbc:oracle:thin:@<IP OR HOSTNAME>:<PORT>:<SERVICE NAME OR SID>"
--referenceUsername=<USERNAME>
--referencePassword=<PASSWORD>
				
diff

See the snapshot command documentation for an example of using a snapshot file as one of the databases being used in the command.

Note: When running diff against two different databases, the class path property should reference both .jar files. Use the path separator that is correct for your operating system (a semicolon on Windows, a colon on Mac or Linux).

Example: classpath: ojdbc7.jar:postgresql-42.2.8.jar

  • Alternatively, configure the liquibase.properties file to include your driver, class path, and URL for both databases. Run the following command:
liquibase --outputFile=mydiff.txt diff

Note: For information on how to configure your liquibase.properties file, view the Creating and configuring a liquibase.properties file topic.

Diff Results:
Reference Database: MYSCHEMA2 @ jdbc:oracle:thin:@localhost:1521:ORCL (Default Schema: MYSCHEMA2)
Comparison Database: MYSCHEMA @ jdbc:oracle:thin:@localhost:1521:ORCL (Default Schema: MYSCHEMA)
Compared Schemas: MYSCHEMA2 -> MYSCHEMA
Product Name: EQUAL
Product Version: EQUAL
Missing Catalog(s): NONE
Unexpected Catalog(s): NONE
Changed Catalog(s): NONE
Missing Check Constraint(s): NONE
Unexpected Check Constraint(s): NONE
Changed Check Constraint(s): NONE
Missing Column(s): NONE
Unexpected Column(s):
	MYSCHEMA.DEPARTMENT.ACTIVE
	MYSCHEMA.SERVICETECH.ACTIVE
	MYSCHEMA.SERVICETECH2.ACTIVE
	MYSCHEMA.SERVICETECH3.ACTIVE
	MYSCHEMA.VIEW1.ACTIVE
	MYSCHEMA.DATABASECHANGELOG.AUTHOR
	MYSCHEMA.DATABASECHANGELOG.COMMENTS
	MYSCHEMA.DATABASECHANGELOG.CONTEXTS
	MYSCHEMA.DATABASECHANGELOG.DATEEXECUTED
	MYSCHEMA.DATABASECHANGELOG.DEPLOYMENT_ID
	MYSCHEMA.DATABASECHANGELOG.DESCRIPTION
	MYSCHEMA.DATABASECHANGELOG.EXECTYPE
	MYSCHEMA.DATABASECHANGELOG.FILENAME
	MYSCHEMA.DATABASECHANGELOG.ID
	MYSCHEMA.DATABASECHANGELOGLOCK.ID
	MYSCHEMA.DEPARTMENT.ID
	MYSCHEMA.SERVICETECH.ID
	MYSCHEMA.SERVICETECH2.ID
	MYSCHEMA.SERVICETECH3.ID
	MYSCHEMA.VIEW1.ID
	MYSCHEMA.DATABASECHANGELOG.LABELS
	MYSCHEMA.DATABASECHANGELOG.LIQUIBASE
	MYSCHEMA.DATABASECHANGELOGLOCK.LOCKED
	MYSCHEMA.DATABASECHANGELOGLOCK.LOCKEDBY
	MYSCHEMA.DATABASECHANGELOGLOCK.LOCKGRANTED
	MYSCHEMA.DATABASECHANGELOG.MD5SUM
	MYSCHEMA.DEPARTMENT.NAME
	MYSCHEMA.SERVICETECH.NAME
	MYSCHEMA.SERVICETECH2.NAME
	MYSCHEMA.SERVICETECH3.NAME
	MYSCHEMA.VIEW1.NAME
	MYSCHEMA.DATABASECHANGELOG.ORDEREXECUTED
	MYSCHEMA.DATABASECHANGELOG.TAG
Changed Column(s): NONE
Missing Database Package(s): NONE
Unexpected Database Package(s): NONE
Changed Database Package(s): NONE
Missing Database Package Body(s): NONE
Unexpected Database Package Body(s): NONE
Changed Database Package Body(s): NONE
Missing Foreign Key(s): NONE
Unexpected Foreign Key(s): NONE
Changed Foreign Key(s): NONE
Missing Function(s): NONE
Unexpected Function(s): NONE
Changed Function(s): NONE
Missing Index(s): NONE
Unexpected Index(s):
	PK_DATABASECHANGELOGLOCK UNIQUE  ON MYSCHEMA.DATABASECHANGELOGLOCK(ID)
	PK_DEPARTMENT UNIQUE  ON MYSCHEMA.DEPARTMENT(ID)
	PK_SERVICETECH UNIQUE  ON MYSCHEMA.SERVICETECH(ID)
	PK_SERVICETECH2 UNIQUE  ON MYSCHEMA.SERVICETECH2(ID)
	PK_SERVICETECH3 UNIQUE  ON MYSCHEMA.SERVICETECH3(ID)
Changed Index(s): NONE
Missing Java Class(s): NONE
Unexpected Java Class(s): NONE
Changed Java Class(s): NONE
Missing Java Source(s): NONE
Unexpected Java Source(s): NONE
Changed Java Source(s): NONE
Missing Primary Key(s): NONE
Unexpected Primary Key(s):
	PK_DATABASECHANGELOGLOCK on MYSCHEMA.DATABASECHANGELOGLOCK(ID)
	PK_DEPARTMENT on MYSCHEMA.DEPARTMENT(ID)
	PK_SERVICETECH on MYSCHEMA.SERVICETECH(ID)
	PK_SERVICETECH2 on MYSCHEMA.SERVICETECH2(ID)
	PK_SERVICETECH3 on MYSCHEMA.SERVICETECH3(ID)
Changed Primary Key(s): NONE
Missing Sequence(s): NONE
Unexpected Sequence(s): NONE
Changed Sequence(s): NONE
Missing Stored Procedure(s): NONE
Unexpected Stored Procedure(s): NONE
Changed Stored Procedure(s): NONE
Missing Synonym(s): NONE
Unexpected Synonym(s): NONE
Changed Synonym(s): NONE
Missing Table(s): NONE
Unexpected Table(s):
	DATABASECHANGELOG
	DATABASECHANGELOGLOCK
	DEPARTMENT
	SERVICETECH
	SERVICETECH2
	SERVICETECH3
Changed Table(s): NONE
Missing Trigger(s): NONE
Unexpected Trigger(s): NONE
Changed Trigger(s): NONE
Missing Unique Constraint(s): NONE
Unexpected Unique Constraint(s): NONE
Changed Unique Constraint(s): NONE
Missing View(s): NONE
Unexpected View(s):
	VIEW1
Changed View(s): NONE
Liquibase command 'diff' was executed successfully.

The diff command produces a list of categories along with one of the following descriptions:

  • Missing: there are objects on your source database (referenceURL) that are not on your target database (URL).
  • Unexpected: there are objects on your target database (URL) that are not on your source database (referenceURL).
  • Changed: the object as it exists on the source database (referenceURL) is different than as it exists in the target database (URL).

Note: The changed description will not specify the type of change applied to your database. Run the diffChangeLog command to generate a changelog that will apply the changes to the target database.

Liquibase Community diff categories:

  • Catalog
  • Column
  • Foreign Key
  • Index
  • Primary Key
  • Schema
  • Sequence
  • Procedure
  • Unique Constraints
  • View

Liquibase Pro diff categories:

  • Check Constraint
  • Package
  • Package Body
  • Function
  • Trigger
  • Synonyms

Note: Liquibase does not currently check datatype length.

Filtering diff types

Liquibase allows you to use diffType attribute to filter the types of objects you want to compare. Multiple filters can be added to the attribute as a comma separated list. If no diffTypes are specified, all objects are considered.

Example: liquibase --diffTypes=tables,indexes,views diff 

Diff Results:
Reference Database: MYSCHEMA2 @ jdbc:oracle:thin:@localhost:1521:ORCL (Default Schema: MYSCHEMA2)
Comparison Database: MYSCHEMA @ jdbc:oracle:thin:@localhost:1521:ORCL (Default Schema: MYSCHEMA)
Compared Schemas: MYSCHEMA2 -> MYSCHEMA
Product Name: EQUAL
Product Version: EQUAL
Missing Index(s): NONE
Unexpected Index(s):
	PK_DATABASECHANGELOGLOCK UNIQUE  ON MYSCHEMA.DATABASECHANGELOGLOCK(ID)
	PK_DEPARTMENT UNIQUE  ON MYSCHEMA.DEPARTMENT(ID)
	PK_SERVICETECH UNIQUE  ON MYSCHEMA.SERVICETECH(ID)
	PK_SERVICETECH2 UNIQUE  ON MYSCHEMA.SERVICETECH2(ID)
	PK_SERVICETECH3 UNIQUE  ON MYSCHEMA.SERVICETECH3(ID)
Changed Index(s): NONE
Missing Table(s): NONE
Unexpected Table(s):
	DATABASECHANGELOG
	DATABASECHANGELOGLOCK
	DEPARTMENT
	SERVICETECH
	SERVICETECH2
	SERVICETECH3
Changed Table(s): NONE
Missing View(s): NONE
Unexpected View(s):
	VIEW1
Changed View(s): NONE
Liquibase command 'diff' was executed successfully.

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