关于数据库迁移
什么是数据库迁移
数据库迁移（Database Migration）是指对数据库结构进行版本控制的过程，它允许开发团队跟踪数据库模式的变更，并确保在不同环境（开发、测试、生产）中数据库结构的一致性。
为什么需要数据库迁移
在传统的软件开发中，数据库变更通常通过手动执行SQL脚本完成，这种方式存在诸多问题：
版本不一致：不同环境的数据库结构可能不一致
协作困难：多人开发时容易产生冲突
回滚复杂：出现问题时难以快速回滚到之前的版本
缺乏历史记录：无法追踪数据库结构的变更历史
Liquibase
Liquibase 是一个开源的数据库迁移工具，它通过 changelog 文件来管理数据库的变更，支持多种格式（XML、JSON、YAML、SQL）的变更定义，能够与多种数据库系统协同工作。
主要特性：
支持多种数据库（MySQL、PostgreSQL、Oracle等）
多种变更定义格式
回滚支持
与Spring Boot无缝集成
丰富的变更类型支持
Spring Boot 集成 Liquibase
添加依赖
首先，在pom.xml中添加 Liquibase 依赖：
<!-- Liquibase Database Migration --> <dependency> <groupId>org.liquibase</groupId> <artifactId>liquibase-core</artifactId> </dependency>Liquibase比起Flyway，对Springboot的支持更好。使用Springboot3也可以运行，Flyway则在Springboot3里面无法使用。
YML配置
# Liquibase Configuration liquibase: enabled: true change-log: classpath:db/changelog/db.changelog-master.xml drop-first: false default-schema: mqtt定义Liquibase的XML
创建主变更日志文件
在src/main/resources/db/changelog目录下创建主变更日志文件db.changelog-master.yaml：
<?xml version="1.0" encoding="UTF-8"?> <databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.20.xsd"> <!-- Include all changelog files --> <include file="db/changelog/changes/v1.0-initial-schema.xml"/> <include file="db/changelog/changes/v1.1-sample-data.xml"/> </databaseChangeLog>v1.0-initial-schema.xml 初始化数据库结构
<?xml version="1.0" encoding="UTF-8"?> <databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.20.xsd"> <!-- Create mqtt_connection table --> <changeSet id="1" author="mqtt-websocket-bridge"> <createTable tableName="mqtt_connection" remarks="MQTT Connection Table"> <column name="id" type="BIGINT" autoIncrement="true"> <constraints primaryKey="true" nullable="false"/> </column> <column name="client_id" type="VARCHAR(255)" remarks="MQTT Client ID"> <constraints nullable="false" unique="true"/> </column> <column name="broker_url" type="VARCHAR(255)" remarks="MQTT Broker URL"> <constraints nullable="false"/> </column> <column name="username" type="VARCHAR(255)" remarks="Username"/> <column name="password" type="VARCHAR(255)" remarks="Password"/> <column name="keep_alive" type="INT" defaultValue="60" remarks="Keep Alive Interval (seconds)"/> <column name="clean_session" type="TINYINT(1)" defaultValue="1" remarks="Clean Session Flag"/> <column name="protocol_version" type="VARCHAR(50)" defaultValue="MQTT 3.1.1" remarks="Protocol Version"/> <column name="tls_enabled" type="TINYINT(1)" defaultValue="0" remarks="TLS Enabled"/> <column name="status" type="INT" defaultValue="0" remarks="Connection Status (0: disconnected, 1: connected)"/> <column name="connected_at" type="DATETIME" remarks="Connection Timestamp"/> <column name="disconnected_at" type="DATETIME" remarks="Disconnection Timestamp"/> <column name="created_at" type="DATETIME" defaultValueComputed="CURRENT_TIMESTAMP" remarks="Create Time"/> <column name="updated_at" type="DATETIME" defaultValueComputed="CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP" remarks="Update Time"/> <column name="deleted" type="INT" defaultValue="0" remarks="Logical Delete Flag"/> </createTable> <!-- Create indexes for mqtt_connection --> <createIndex indexName="idx_client_id" tableName="mqtt_connection"> <column name="client_id"/> </createIndex> <createIndex indexName="idx_status" tableName="mqtt_connection"> <column name="status"/> </createIndex> <createIndex indexName="idx_created_at" tableName="mqtt_connection"> <column name="created_at"/> </createIndex> </changeSet> <!-- Create mqtt_subscription table --> <changeSet id="2" author="mqtt-websocket-bridge"> <createTable tableName="mqtt_subscription" remarks="MQTT Subscription Table"> <column name="id" type="BIGINT" autoIncrement="true"> <constraints primaryKey="true" nullable="false"/> </column> <column name="client_id" type="VARCHAR(255)" remarks="MQTT Client ID"> <constraints nullable="false"/> </column> <column name="topic" type="VARCHAR(500)" remarks="MQTT Topic"> <constraints nullable="false"/> </column> <column name="qos" type="INT" defaultValue="0" remarks="Quality of Service (0, 1, 2)"/> <column name="subscribed_at" type="DATETIME" defaultValueComputed="CURRENT_TIMESTAMP" remarks="Subscription Timestamp"/> <column name="created_at" type="DATETIME" defaultValueComputed="CURRENT_TIMESTAMP" remarks="Create Time"/> <column name="updated_at" type="DATETIME" defaultValueComputed="CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP" remarks="Update Time"/> <column name="deleted" type="INT" defaultValue="0" remarks="Logical Delete Flag"/> </createTable> <!-- Create indexes for mqtt_subscription --> <createIndex indexName="idx_client_id" tableName="mqtt_subscription"> <column name="client_id"/> </createIndex> <createIndex indexName="idx_topic" tableName="mqtt_subscription"> <column name="topic"/> </createIndex> <createIndex indexName="idx_subscribed_at" tableName="mqtt_subscription"> <column name="subscribed_at"/> </createIndex> <!-- Create unique constraint --> <addUniqueConstraint tableName="mqtt_subscription" columnNames="client_id, topic" constraintName="uk_client_topic"/> </changeSet> <!-- Create mqtt_message table --> <changeSet id="3" author="mqtt-websocket-bridge"> <createTable tableName="mqtt_message" remarks="MQTT Message Table"> <column name="id" type="BIGINT" autoIncrement="true"> <constraints primaryKey="true" nullable="false"/> </column> <column name="client_id" type="VARCHAR(255)" remarks="MQTT Client ID"> <constraints nullable="false"/> </column> <column name="topic" type="VARCHAR(500)" remarks="MQTT Topic"> <constraints nullable="false"/> </column> <column name="payload" type="TEXT" remarks="Message Payload"/> <column name="qos" type="INT" defaultValue="0" remarks="Quality of Service (0, 1, 2)"/> <column name="retained" type="TINYINT(1)" defaultValue="0" remarks="Retained Message Flag"/> <column name="direction" type="VARCHAR(50)" remarks="Message Direction (INBOUND, OUTBOUND)"> <constraints nullable="false"/> </column> <column name="created_at" type="DATETIME" defaultValueComputed="CURRENT_TIMESTAMP" remarks="Create Time"/> <column name="deleted" type="INT" defaultValue="0" remarks="Logical Delete Flag"/> </createTable> <!-- Create indexes for mqtt_message --> <createIndex indexName="idx_client_id" tableName="mqtt_message"> <column name="client_id"/> </createIndex> <createIndex indexName="idx_topic" tableName="mqtt_message"> <column name="topic"/> </createIndex> <createIndex indexName="idx_direction" tableName="mqtt_message"> <column name="direction"/> </createIndex> <createIndex indexName="idx_created_at" tableName="mqtt_message"> <column name="created_at"/> </createIndex> </changeSet> </databaseChangeLog>v1.1-sample-data.xml 初始化数据
<?xml version="1.0" encoding="UTF-8"?> <databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.20.xsd"> <!-- Insert sample connection data --> <changeSet id="4" author="mqtt-websocket-bridge"> <insert tableName="mqtt_connection"> <column name="client_id" value="emqx_NJEONID"/> <column name="broker_url" value="tcp://localhost:1883"/> <column name="username" value=""/> <column name="password" value=""/> <column name="keep_alive" valueNumeric="60"/> <column name="clean_session" valueNumeric="1"/> <column name="protocol_version" value="MQTT 5"/> <column name="status" valueNumeric="0"/> </insert> </changeSet> </databaseChangeLog>
