Liquibase Preconditions Errors

Preconditions are used to check if the database has all the requirements met for the ChangeSet to run to avoid any future errors, but sometimes there is an error in checking Preconditions and Preconditions fail to execute. since required Preconditions is not checked, now Liquibase doesn't know whether to abort or continue with the ChangeSet.

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
	<changeSet author="wesome" id="1692968322140-1">
		<preConditions>
			<tableExists schemaName="appledb" tableName="apple" />
		</preConditions>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_id" value="1" />
			<column name="apple_name" value="Macintosh" />
			<column name="current_date_time" valueDate="2023-08-25T18:27:48" />
		</insert>
	</changeSet>
</databaseChangeLog>

liquibase.properties (update changeLog File file format with SQL, XML, YAML, JSON as per changelog.mysql.)

changeLogFile=changelog.mysql.xml
liquibase.command.url:jdbc:mysql://localhost:3306/appleDb?createDatabaseIfNotExist=true&autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true
liquibase.command.username : root
liquibase.command.password : rootroot

The above precondition is checking that the apple table should have at least 5 rows, but it results in an error because the apple table doesn't exist.

Running Changeset: changelog.mysql.xml::1692968322140-1::wesome
Unexpected error running Liquibase: Migration failed for changeset changelog.mysql.xml::1692968322140-1::wesome:        
Reason: changelog.mysql.xml : liquibase.precondition.core.RowCountPrecondition@2fd954f : Table 'appledb.apple' doesn't exist
  - Caused by: Precondition Error
  - Caused by: Error executing SQL SELECT COUNT(*) FROM appleDb.apple: Table 'appledb.apple' doesn't exist

Custom message for Preconditions Error

Liquibase provides an onErrorMessage attribute to provide custom messages when an error occurs.

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
	<changeSet author="wesome" id="1692968322140-1">
		<preConditions onErrorMessage="condition fail:- apple table should have minimum 5 rows">
			<rowCount expectedRows="5" tableName="apple" />
		</preConditions>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_id" value="1" />
			<column name="apple_name" value="Macintosh" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
	</changeSet>
</databaseChangeLog>

liquibase.properties (update changeLog File file format with SQL, XML, YAML, JSON as per changelog.mysql.)

changeLogFile=changelog.mysql.xml
liquibase.command.url:jdbc:mysql://localhost:3306/appleDb?createDatabaseIfNotExist=true&autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true
liquibase.command.username : root
liquibase.command.password : rootroot

Preconditions onError attributes

To deal with error scenarios, Liquibase provides an onError attribute, which controls what should happen if Preconditions fails to execute. onError supports CONTINUE, HALT, MARK_RAN, WARN. let's see them one by one.

Preconditions onError Continue

onError=CONTINUE will skip the ChangeSet and will continue with the next ChangeSet. Liquibase will try to execute this ChangeSet on the next update.

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
	<changeSet author="wesome" id="1692968322140-1">
		<preConditions onError="CONTINUE" onErrorMessage="condition fail:- apple table should have minimum 5 rows">
			<rowCount expectedRows="5" tableName="apple" />
		</preConditions>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_id" value="1" />
			<column name="apple_name" value="Macintosh" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
	</changeSet>
	<changeSet author="wesome" id="1692968322140-2">
		<createTable catalogName="appledb" tableName="apple">
			<column autoIncrement="true" name="apple_id" type="BIGINT">
				<constraints nullable="false" primaryKey="true" />
			</column>
			<column name="apple_name" type="VARCHAR(255)" />
		</createTable>
	</changeSet>
</databaseChangeLog>

liquibase.properties (update changeLog File file format with SQL, XML, YAML, JSON as per changelog.mysql.)

changeLogFile=changelog.mysql.xml
liquibase.command.url:jdbc:mysql://localhost:3306/appleDb?createDatabaseIfNotExist=true&autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true
liquibase.command.username : root
liquibase.command.password : rootroot

Preconditions onError Halt

onError=HALT will abort the execution of the entire ChangeLog file. Hallt is the default value of onError.

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
	<changeSet author="wesome" id="1692968322140-1">
		<preConditions onError="HALT" onErrorMessage="condition fail:- apple table should have minimum 5 rows">
			<rowCount expectedRows="5" tableName="apple" />
		</preConditions>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_id" value="1" />
			<column name="apple_name" value="Macintosh" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
	</changeSet>
	<changeSet author="wesome" id="1692968322140-2">
		<createTable catalogName="appledb" tableName="apple">
			<column autoIncrement="true" name="apple_id" type="BIGINT">
				<constraints nullable="false" primaryKey="true" />
			</column>
			<column name="apple_name" type="VARCHAR(255)" />
		</createTable>
	</changeSet>
</databaseChangeLog>

liquibase.properties (update changeLog File file format with SQL, XML, YAML, JSON as per changelog.mysql.)

changeLogFile=changelog.mysql.xml
liquibase.command.url:jdbc:mysql://localhost:3306/appleDb?createDatabaseIfNotExist=true&autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true
liquibase.command.username : root
liquibase.command.password : rootroot

Preconditions onError MARK RAN

onError=MARK_RAN will skip the execution of the current ChangeSet but it will mark the current ChangeSet as executed in DATABASECHANGELOG table, and continue with the next ChangeSet.

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
	<changeSet author="wesome" id="1692968322140-1">
		<preConditions onError="MARK_RAN" onErrorMessage="condition fail:- apple table should have minimum 5 rows">
			<rowCount expectedRows="5" tableName="apple" />
		</preConditions>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_id" value="1" />
			<column name="apple_name" value="Macintosh" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
	</changeSet>
	<changeSet author="wesome" id="1692968322140-2">
		<createTable catalogName="appledb" tableName="apple">
			<column autoIncrement="true" name="apple_id" type="BIGINT">
				<constraints nullable="false" primaryKey="true" />
			</column>
			<column name="apple_name" type="VARCHAR(255)" />
		</createTable>
	</changeSet>
</databaseChangeLog>

liquibase.properties (update changeLog File file format with SQL, XML, YAML, JSON as per changelog.mysql.)

changeLogFile=changelog.mysql.xml
liquibase.command.url:jdbc:mysql://localhost:3306/appleDb?createDatabaseIfNotExist=true&autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true
liquibase.command.username : root
liquibase.command.password : rootroot

Even though the ChangeSet has failed, it still is marked as executed successfully and can be verified by running a query

select * from appledb.DATABASECHANGELOG;

Preconditions onError WARN

onError=WARN will send a warning and continue executing the ChangeSet.

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext" xmlns:pro="http://www.liquibase.org/xml/ns/pro" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd">
	<changeSet author="wesome" id="1692968322140-1">
		<preConditions onError="WARN" onErrorMessage="condition fail:- apple table should have minimum 5 rows">
			<rowCount expectedRows="5" tableName="apple" />
		</preConditions>
		<insert catalogName="appledb" tableName="apple">
			<column name="apple_id" value="1" />
			<column name="apple_name" value="Macintosh" />
			<column name="current_date_time" valueDate="now()" />
		</insert>
	</changeSet>
	<changeSet author="wesome" id="1692968322140-2">
		<createTable catalogName="appledb" tableName="apple">
			<column autoIncrement="true" name="apple_id" type="BIGINT">
				<constraints nullable="false" primaryKey="true" />
			</column>
			<column name="apple_name" type="VARCHAR(255)" />
		</createTable>
	</changeSet>
</databaseChangeLog>

liquibase.properties (update changeLog File file format with SQL, XML, YAML, JSON as per changelog.mysql.)

changeLogFile=changelog.mysql.xml
liquibase.command.url:jdbc:mysql://localhost:3306/appleDb?createDatabaseIfNotExist=true&autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true
liquibase.command.username : root
liquibase.command.password : rootroot