Overview

Summary	Uses `pt-online-schema-change` in order to add or drop columns.
Current Version	1.0.0
Author	Andreas Dangel (adangel [at] users.sf.net)
Issue Tracking	https://github.com/adangel/liquibase-percona/issues
Source Repository	https://github.com/adangel/liquibase-percona.git
Maven Coordinates	com.github.adangel.liquibase.ext:liquibase-percona
Supported Database	MySQL

News

October 19, 2014

1.0.0

	File	Modified

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Readme

Supported Databases

MySQL is the only supported database. The extension checks whether it is being run against a MySQL database. If not, it falls back to the default AddColumn/DropColumn change of liquibase-core.

Liquibase version(s) tested against

Liquibase 3.2.0

Example

This changeset

<changeSet id="2" author="Alice">
    <addColumn tableName="person">
        <column name="address" type="varchar(255)"/>
    </addColumn>
</changeSet>

will execute the following command:

pt-online-schema-change --alter="ADD COLUMN address VARCHAR(255)" --host=127.0.0.1 --port=3306 --user=root --password=** --execute D=testdb,t=person

Configuration

The extension supports the following java system properties:

liquibase.percona.failIfNoPT: true/false. Default: false. If set to true, the database upate will fail, if the command pt-online-schema-change is not found. This can be used, to enforce, that percona toolkit is used.
liquibase.percona.noAlterSqlDryMode: true/false. Default: false. When running updateSQL or rollbackSQL in order to generate a migration SQL file, the command line, that would be executed, will be added as a comment. In addition, the SQL statements (as produced by liquibase-core) will also be generated and output into the migration file. This allows to simply execute the generated migration SQL to perform an update. However, the Percona toolkit won't be used. If this property is set to true, then no such SQL statements will be output into the migration file.

Notes

The non-locking update is achieved using triggers. First a new temporary table is created, including the added or dropped columns. Then the data is copied in chunks. While to copy is in progress, any newly created or deleted or updated rows are copied, too. This is done by adding triggers to the original table. After the copy is finished, the original table is dropped and the temporary table is renamed.

This means, that pt-online-schema-change cannot be used, if the table already uses triggers.

The command pt-online-schema-change is searched only on the PATH.

Building this extension

Simply run mvn clean install.

In order to execute the integration tests, run mvn clean install -Prun-its. Please note, that a MySQL server/Percona server is needed. See the properties config_... in pom.xml for connection details.

Percona Online Schema Change