feat: add a pluggable JDBC dialect layer with MySQL support

Fold Flyway V1-V7 into per-dialect baselines and resolve Boot 3/4 Flyway customizer types without a DataSource creation cycle.

Co-authored-by: Cursor <cursoragent@cursor.com>

README.md

@@ -10,11 +10,11 @@
 |---|---|
 | `ordo-api` | 公共模型与 `OrdoEngine` 端口 |
 | `ordo-core` | 运行时（`DefaultOrdoEngine` / `InMemoryOrdoEngine`） |
-| `ordo-storage-jdbc` | JDBC 存储 + Flyway 迁移（V1–V7） |
+| `ordo-storage-jdbc` | JDBC 存储 + 按方言 Flyway 基线（PostgreSQL / MySQL） |
 | `ordo-spring-boot-starter` | Spring Boot 自动装配（JDBC + Flyway） |
 | `ordo-example` | 内存引擎示例 |
 
-存储实现面向 **PostgreSQL**（测试可用 H2 PostgreSQL 兼容模式）。Starter **不携带** JDBC 驱动，宿主自行加入 `postgresql` 或 `h2`。Spring Boot 4 还需额外引入 `spring-boot-starter-flyway`，否则迁移不会跑。
+存储实现通过 dialect 层支持 **PostgreSQL** 与 **MySQL**（测试可用 H2 PostgreSQL 兼容模式）。Starter **不携带** JDBC 驱动，宿主自行加入 `postgresql`、`mysql-connector-j` 或 `h2`。Spring Boot 4 还需额外引入 `spring-boot-starter-flyway`，否则迁移不会跑。
 
 ## 能力
 
@@ -29,7 +29,7 @@
 - 审计时间线：`ProcessEvent` + `queryHistory`
 - 扩展点：`AssigneeResolver`、`RoutingCondition`、`ActionHandler`、`OrdoEventListener`
 
-开发计划：MySQL 方言、可选 REST + 目录 SPI。设计器为独立产品（不进本仓库），待 REST 与目录之后。多租户 **暂不在计划中**。见 [docs/roadmap.md](docs/roadmap.md)。
+开发计划：可选 REST + 目录 SPI。设计器为独立产品（不进本仓库），待 REST 与目录之后。多租户 **暂不在计划中**。见 [docs/roadmap.md](docs/roadmap.md)。
 
 详细用法（定义 JSON、扩展点、异常、查询、ACTION/审计语义）见 **[docs/usage.md](docs/usage.md)**。对外行为变更时同步更新该文档。
 
@@ -100,8 +100,10 @@ ordo.approve(manager.id(), "maria", "ok");
 ```yaml
 ordo:
   enabled: true
+  jdbc:
+    dialect:     # 可选 postgresql / mysql；空则按 DataSource 探测
   definitions:
-    location: classpath*:ordo/*.json   # 默认值；启动时 replace 加载
+    location: classpath*:ordo/*.json   # 默认值；启动时 publish 加载
 ```
 
 宿主提供 Bean 即可覆盖默认值：

docs/roadmap.md

@@ -7,7 +7,7 @@
 ## 已完成
 
 - ANY/ALL 会签/或签
-- JDBC 存储（PostgreSQL）+ Flyway V1–V7
+- JDBC 存储（PostgreSQL / MySQL）+ 按方言 Flyway 基线
 - 定义不可变多版本：`publish`；实例锁定 `definitionVersion`
 - 条件路由 `StepTransition` + `RoutingCondition`
 - ACTION + `ActionHandler`；执行记录持久化
@@ -22,10 +22,6 @@
 
 下列能力已纳入计划，尚未实现。实现顺序可按依赖调整，但范围本身不从计划中拿掉。
 
-### MySQL 方言
-
-当前 JDBC DDL/冲突处理面向 PostgreSQL。计划增加 MySQL 方言（及对应测试），通过 dialect 层扩展，而不是只支持一种库。
-
 ### 可选 REST + 目录 SPI
 
 引擎入口仍是 `OrdoEngine`。计划提供**可选、极薄**的 REST 适配（例如独立 starter），带 OpenAPI，覆盖定义读写/解析校验、实例与任务查询，不包含鉴权、RBAC、业务表单。

docs/usage.md

@@ -12,7 +12,7 @@ Ordo 是嵌入宿主进程的审批引擎，入口是 `OrdoEngine`。
 
 产品边界：不做业务表单、用户体系、多租户；不内置设计器 UI。业务字段放在 `ProcessContext`（不可变 `Map<String, Object>`）。当前也**没有** REST；HTTP 仍由宿主自建。计划中的可选 REST 与独立设计器见 [roadmap.md](roadmap.md)。
 
-开发计划（尚未提供，见 [roadmap.md](roadmap.md)）：MySQL 方言、可选 REST + 目录 SPI。
+开发计划（尚未提供，见 [roadmap.md](roadmap.md)）：可选 REST + 目录 SPI。
 
 ## 2. 模块与接入
 
@@ -20,11 +20,11 @@ Ordo 是嵌入宿主进程的审批引擎，入口是 `OrdoEngine`。
 |---|---|
 | `ordo-api` | 始终：模型与 `OrdoEngine` |
 | `ordo-core` | 内存引擎 / 自己装配 `DefaultOrdoEngine` |
-| `ordo-storage-jdbc` | JDBC 持久化（PostgreSQL；测试可用 H2 PostgreSQL 模式） |
+| `ordo-storage-jdbc` | JDBC 持久化（PostgreSQL、MySQL；测试可用 H2 PostgreSQL 模式） |
 | `ordo-spring-boot-starter` | Spring Boot 自动装配 |
 | `ordo-example` | `LeaveRequestExample` 内存演示 |
 
-Starter **不携带** JDBC 驱动。生产加 `org.postgresql:postgresql`。Spring Boot 4 还需 `spring-boot-starter-flyway`，否则 Flyway 迁移不会执行。
+Starter **不携带** JDBC 驱动。生产按库添加 `org.postgresql:postgresql` 或 `com.mysql:mysql-connector-j`。Spring Boot 4 还需 `spring-boot-starter-flyway`，否则 Flyway 迁移不会执行。
 
 先 `mvn install` 本仓库，宿主再依赖 `0.0.1-SNAPSHOT`。
 
@@ -60,6 +60,8 @@ OrdoEngine ordo = new InMemoryOrdoEngine();
 ```yaml
 ordo:
   enabled: true
+  jdbc:
+    dialect:     # 可选 postgresql / mysql；空则按 DataSource 探测
   definitions:
     location: classpath*:ordo/*.json   # 启动时对每个 JSON 调用 publish
   due:
@@ -345,12 +347,14 @@ ACTION 成功事件发生在提交之后，因此排在同轮事务内写入的
 
 ## 12. 存储
 
-Flyway 脚本在 `ordo-storage-jdbc` 的 `db/migration`（V1–V7）。表包括流程头 `ordo_process`、按 `(id, version)` 存储的定义/步骤/候选人/转移、实例（含 `definition_version`）、任务、`ordo_process_event`、`ordo_action_execution`。
+Flyway 脚本按方言分目录：`db/postgresql/migration`、`db/mysql/migration`（各一份当前 schema 的 `V1__baseline.sql`）。未设置 `spring.flyway.locations` 时，starter 按探测到的方言指向对应目录。已有 `flyway_schema_history` 的开发库需清空后重跑。表包括流程头 `ordo_process`、按 `(id, version)` 存储的定义/步骤/候选人/转移、实例（含 `definition_version`）、任务、`ordo_process_event`、`ordo_action_execution`。
+
+自定义方言：实现 `SqlDialect` 并用 `META-INF/services` 注册，或提供 `SqlDialect` Bean。新增列时每个已支持方言目录各加一条迁移。
 
 多 JVM 共享同一库时，多步写入走 `TransactionExecutor`，完成任务/实例用条件更新（仍 PENDING / 仍 RUNNING 才改），避免双花。
 
 ## 13. 未提供能力
 
-开发计划中（见 [roadmap.md](roadmap.md)）：MySQL 方言、可选 REST + 目录 SPI。独立设计器不进本仓库，等 REST 与目录之后再做。
+开发计划中（见 [roadmap.md](roadmap.md)）：可选 REST + 目录 SPI。独立设计器不进本仓库，等 REST 与目录之后再做。
 
 暂不在计划中：多租户、设计器 UI。当前 REST 由宿主自建。

ordo-spring-boot-autoconfigure/pom.xml

@@ -58,6 +58,14 @@
             <groupId>org.flywaydb</groupId>
             <artifactId>flyway-core</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-database-postgresql</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-mysql</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-configuration-processor</artifactId>

ordo-spring-boot-autoconfigure/src/main/java/com/jetlumen/ordo/spring/OrdoFlywayAutoConfiguration.java

@@ -0,0 +1,123 @@
+package com.jetlumen.ordo.spring;
+
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
+import org.flywaydb.core.Flyway;
+import org.flywaydb.core.api.configuration.FluentConfiguration;
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.AutoConfigureBefore;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.core.env.Environment;
+
+import javax.sql.DataSource;
+import java.lang.reflect.Proxy;
+
+/**
+ * Points Flyway at the dialect migration directory before Flyway runs.
+ * Host {@code spring.flyway.locations} is left unchanged when set.
+ *
+ * <p>Does not inject {@link DataSource} or {@link SqlDialect} at bean-creation time
+ * (that would cycle with DataSource → Flyway → customizer). Dialect is resolved inside
+ * {@code customize} from the FluentConfiguration DataSource / {@code ordo.jdbc.dialect}.
+ *
+ * <p>FlywayConfigurationCustomizer moved between Boot 3 and Boot 4; a reflective
+ * {@link FactoryBean} supplies a proxy for whichever type is on the classpath.
+ */
+@AutoConfiguration
+@ConditionalOnProperty(prefix = "ordo", name = "enabled", havingValue = "true", matchIfMissing = true)
+@ConditionalOnClass({DataSource.class, Flyway.class})
+@ConditionalOnBean(DataSource.class)
+@AutoConfigureAfter(name = {
+        "org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration",
+        "org.springframework.boot.jdbc.autoconfigure.DataSourceAutoConfiguration"
+})
+@AutoConfigureBefore(name = {
+        "org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration",
+        "org.springframework.boot.flyway.autoconfigure.FlywayAutoConfiguration"
+})
+@EnableConfigurationProperties(OrdoProperties.class)
+public class OrdoFlywayAutoConfiguration {
+
+    private static final String[] FLYWAY_CUSTOMIZER_TYPES = {
+            "org.springframework.boot.flyway.autoconfigure.FlywayConfigurationCustomizer",
+            "org.springframework.boot.autoconfigure.flyway.FlywayConfigurationCustomizer"
+    };
+
+    @Bean
+    @ConditionalOnClass(name = "org.flywaydb.core.api.configuration.FluentConfiguration")
+    public FactoryBean<Object> ordoFlywayConfigurationCustomizer(
+            OrdoProperties ordoProperties, Environment environment) {
+        Class<?> customizerType = resolveFlywayCustomizerType();
+        if (customizerType == null) {
+            return null;
+        }
+        return new FlywayLocationsCustomizerFactoryBean(customizerType, ordoProperties, environment);
+    }
+
+    static Class<?> resolveFlywayCustomizerType() {
+        ClassLoader classLoader = OrdoFlywayAutoConfiguration.class.getClassLoader();
+        for (String name : FLYWAY_CUSTOMIZER_TYPES) {
+            try {
+                return Class.forName(name, false, classLoader);
+            } catch (ClassNotFoundException ignored) {
+                // Boot 3 vs Boot 4
+            }
+        }
+        return null;
+    }
+
+    private static final class FlywayLocationsCustomizerFactoryBean implements FactoryBean<Object> {
+        private final Class<?> customizerType;
+        private final OrdoProperties ordoProperties;
+        private final Environment environment;
+
+        private FlywayLocationsCustomizerFactoryBean(Class<?> customizerType, OrdoProperties ordoProperties,
+                                                     Environment environment) {
+            this.customizerType = customizerType;
+            this.ordoProperties = ordoProperties;
+            this.environment = environment;
+        }
+
+        @Override
+        public Object getObject() {
+            return Proxy.newProxyInstance(customizerType.getClassLoader(), new Class<?>[] {customizerType},
+                    (proxy, method, args) -> {
+                        String name = method.getName();
+                        if ("customize".equals(name) && args != null && args.length == 1) {
+                            applyLocations((FluentConfiguration) args[0]);
+                            return null;
+                        }
+                        if ("equals".equals(name)) {
+                            return proxy == args[0];
+                        }
+                        if ("hashCode".equals(name)) {
+                            return System.identityHashCode(proxy);
+                        }
+                        if ("toString".equals(name)) {
+                            return "OrdoFlywayLocationsCustomizer";
+                        }
+                        throw new UnsupportedOperationException(method.toString());
+                    });
+        }
+
+        private void applyLocations(FluentConfiguration configuration) {
+            if (environment.containsProperty("spring.flyway.locations")) {
+                return;
+            }
+            SqlDialect dialect = SqlDialects.resolve(configuration.getDataSource(),
+                    ordoProperties.getJdbc().getDialect());
+            configuration.locations(dialect.flywayLocations());
+        }
+
+        @Override
+        public Class<?> getObjectType() {
+            return customizerType;
+        }
+    }
+}

ordo-spring-boot-autoconfigure/src/main/java/com/jetlumen/ordo/spring/OrdoJdbcAutoConfiguration.java

@@ -19,6 +19,8 @@ import com.jetlumen.ordo.storage.jdbc.JdbcProcessDefinitionRepository;
 import com.jetlumen.ordo.storage.jdbc.JdbcProcessHistoryRepository;
 import com.jetlumen.ordo.storage.jdbc.JdbcProcessInstanceRepository;
 import com.jetlumen.ordo.storage.jdbc.JdbcTransactionExecutor;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
@@ -49,7 +51,8 @@ import java.time.Clock;
         "org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration",
         // Spring Boot 4.x locations (JDBC/Flyway autoconfiguration moved to dedicated modules)
         "org.springframework.boot.jdbc.autoconfigure.DataSourceAutoConfiguration",
-        "org.springframework.boot.flyway.autoconfigure.FlywayAutoConfiguration"
+        "org.springframework.boot.flyway.autoconfigure.FlywayAutoConfiguration",
+        "com.jetlumen.ordo.spring.OrdoFlywayAutoConfiguration"
 })
 @EnableConfigurationProperties(OrdoProperties.class)
 public class OrdoJdbcAutoConfiguration {
@@ -78,6 +81,12 @@ public class OrdoJdbcAutoConfiguration {
         return ActionHandler.noop();
     }
 
+    @Bean
+    @ConditionalOnMissingBean
+    public SqlDialect ordoSqlDialect(DataSource dataSource, OrdoProperties ordoProperties) {
+        return SqlDialects.resolve(dataSource, ordoProperties.getJdbc().getDialect());
+    }
+
     @Bean
     @ConditionalOnMissingBean
     @DependsOnDatabaseInitialization
@@ -93,32 +102,37 @@ public class OrdoJdbcAutoConfiguration {
 
     @Bean
     @ConditionalOnMissingBean
-    public ProcessDefinitionRepository ordoProcessDefinitionRepository(JdbcConnectionProvider connectionProvider) {
-        return new JdbcProcessDefinitionRepository(connectionProvider);
+    public ProcessDefinitionRepository ordoProcessDefinitionRepository(
+            JdbcConnectionProvider connectionProvider, SqlDialect ordoSqlDialect) {
+        return new JdbcProcessDefinitionRepository(connectionProvider, ordoSqlDialect);
     }
 
     @Bean
     @ConditionalOnMissingBean
-    public ProcessInstanceRepository ordoProcessInstanceRepository(JdbcConnectionProvider connectionProvider) {
-        return new JdbcProcessInstanceRepository(connectionProvider);
+    public ProcessInstanceRepository ordoProcessInstanceRepository(
+            JdbcConnectionProvider connectionProvider, SqlDialect ordoSqlDialect) {
+        return new JdbcProcessInstanceRepository(connectionProvider, ordoSqlDialect);
     }
 
     @Bean
     @ConditionalOnMissingBean
-    public ApprovalTaskRepository ordoApprovalTaskRepository(JdbcConnectionProvider connectionProvider) {
-        return new JdbcApprovalTaskRepository(connectionProvider);
+    public ApprovalTaskRepository ordoApprovalTaskRepository(
+            JdbcConnectionProvider connectionProvider, SqlDialect ordoSqlDialect) {
+        return new JdbcApprovalTaskRepository(connectionProvider, ordoSqlDialect);
     }
 
     @Bean
     @ConditionalOnMissingBean
-    public ProcessHistoryRepository ordoProcessHistoryRepository(JdbcConnectionProvider connectionProvider) {
-        return new JdbcProcessHistoryRepository(connectionProvider);
+    public ProcessHistoryRepository ordoProcessHistoryRepository(
+            JdbcConnectionProvider connectionProvider, SqlDialect ordoSqlDialect) {
+        return new JdbcProcessHistoryRepository(connectionProvider, ordoSqlDialect);
     }
 
     @Bean
     @ConditionalOnMissingBean
-    public ActionExecutionRepository ordoActionExecutionRepository(JdbcConnectionProvider connectionProvider) {
-        return new JdbcActionExecutionRepository(connectionProvider);
+    public ActionExecutionRepository ordoActionExecutionRepository(
+            JdbcConnectionProvider connectionProvider, SqlDialect ordoSqlDialect) {
+        return new JdbcActionExecutionRepository(connectionProvider, ordoSqlDialect);
     }
 
     @Bean

ordo-spring-boot-autoconfigure/src/main/java/com/jetlumen/ordo/spring/OrdoProperties.java

@@ -11,6 +11,7 @@ public class OrdoProperties {
 
     private final Definitions definitions = new Definitions();
     private final Due due = new Due();
+    private final Jdbc jdbc = new Jdbc();
 
     public boolean isEnabled() {
         return enabled;
@@ -28,6 +29,10 @@ public class OrdoProperties {
         return due;
     }
 
+    public Jdbc getJdbc() {
+        return jdbc;
+    }
+
     public static class Definitions {
         private String location = "classpath*:ordo/*.json";
 
@@ -52,4 +57,17 @@ public class OrdoProperties {
             this.pollMs = pollMs;
         }
     }
+
+    public static class Jdbc {
+        /** Explicit dialect id ({@code postgresql}, {@code mysql}). Empty means detect from the DataSource. */
+        private String dialect;
+
+        public String getDialect() {
+            return dialect;
+        }
+
+        public void setDialect(String dialect) {
+            this.dialect = dialect;
+        }
+    }
 }

ordo-spring-boot-autoconfigure/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -1 +1,2 @@
+com.jetlumen.ordo.spring.OrdoFlywayAutoConfiguration
 com.jetlumen.ordo.spring.OrdoJdbcAutoConfiguration

ordo-spring-boot-autoconfigure/src/test/java/com/jetlumen/ordo/spring/OrdoJdbcAutoConfigurationTest.java

@@ -13,6 +13,7 @@ import com.jetlumen.ordo.api.ProcessInstance;
 import com.jetlumen.ordo.api.RoutingCondition;
 import com.jetlumen.ordo.api.query.PageRequest;
 import com.jetlumen.ordo.api.repository.ProcessDefinitionRepository;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
 import org.junit.jupiter.api.Test;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration;
@@ -34,7 +35,8 @@ class OrdoJdbcAutoConfigurationTest {
 
     private final ApplicationContextRunner withDataSourceRunner = new ApplicationContextRunner()
             .withConfiguration(AutoConfigurations.of(
-                    DataSourceAutoConfiguration.class, FlywayAutoConfiguration.class, OrdoJdbcAutoConfiguration.class))
+                    DataSourceAutoConfiguration.class, OrdoFlywayAutoConfiguration.class,
+                    FlywayAutoConfiguration.class, OrdoJdbcAutoConfiguration.class))
             .withPropertyValues(
                     "spring.datasource.url=jdbc:h2:mem:ordo_" + UUID.randomUUID()
                             + ";MODE=PostgreSQL;DATABASE_TO_LOWER=TRUE;DB_CLOSE_DELAY=-1",
@@ -47,6 +49,7 @@ class OrdoJdbcAutoConfigurationTest {
     void assemblesJdbcBackedEngineWhenDataSourceIsPresent() {
         withDataSourceRunner.run(context -> {
             assertThat(context).hasSingleBean(OrdoEngine.class);
+            assertThat(context.getBean(SqlDialect.class).id()).isEqualTo("postgresql");
             OrdoEngine engine = context.getBean(OrdoEngine.class);
 
             engine.publish(LEAVE_REQUEST);
@@ -60,6 +63,12 @@ class OrdoJdbcAutoConfigurationTest {
         });
     }
 
+    @Test
+    void honoursExplicitMysqlDialect() {
+        withDataSourceRunner.withPropertyValues("ordo.jdbc.dialect=mysql", "spring.flyway.enabled=false")
+                .run(context -> assertThat(context.getBean(SqlDialect.class).id()).isEqualTo("mysql"));
+    }
+
     @Test
     void backsOffWhenNoDataSourceBeanIsPresent() {
         withoutDataSourceRunner.run(context ->

ordo-spring-boot-starter/pom.xml

@@ -47,16 +47,22 @@
         <!--
             Flyway 10+ split PostgreSQL support out of flyway-core into this dialect
             module. It is required for migrations to run against PostgreSQL; H2 support
-            remains bundled in flyway-core so tests need nothing extra.
+            remains bundled in flyway-core so tests need nothing extra. flyway-mysql is
+            required for MySQL / MariaDB.
         -->
         <dependency>
             <groupId>org.flywaydb</groupId>
             <artifactId>flyway-database-postgresql</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-mysql</artifactId>
+        </dependency>
         <!--
             No JDBC driver is bundled. Add the driver for your target database yourself, e.g.:
-              org.postgresql:postgresql   (production)
-              com.h2database:h2           (tests / local dev)
+              org.postgresql:postgresql
+              com.mysql:mysql-connector-j
+              com.h2database:h2
         -->
     </dependencies>
 

ordo-storage-jdbc/pom.xml

@@ -32,6 +32,11 @@
             <artifactId>postgresql</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.mysql</groupId>
+            <artifactId>mysql-connector-j</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter</artifactId>

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/JdbcActionExecutionRepository.java

@@ -5,6 +5,8 @@ import com.jetlumen.ordo.api.ActionExecutionStatus;
 import com.jetlumen.ordo.api.query.Page;
 import com.jetlumen.ordo.api.query.PageRequest;
 import com.jetlumen.ordo.api.repository.ActionExecutionRepository;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
 import com.jetlumen.ordo.storage.jdbc.mapper.ActionExecutionMapper;
 
 import java.sql.Connection;
@@ -28,9 +30,15 @@ public final class JdbcActionExecutionRepository implements ActionExecutionRepos
                     + " WHERE id = ? AND status = 'PENDING'";
 
     private final JdbcConnectionProvider connectionProvider;
+    private final SqlDialect dialect;
 
     public JdbcActionExecutionRepository(JdbcConnectionProvider connectionProvider) {
+        this(connectionProvider, SqlDialects.postgresql());
+    }
+
+    public JdbcActionExecutionRepository(JdbcConnectionProvider connectionProvider, SqlDialect dialect) {
         this.connectionProvider = Objects.requireNonNull(connectionProvider, "connectionProvider must not be null");
+        this.dialect = Objects.requireNonNull(dialect, "dialect must not be null");
     }
 
     @Override
@@ -71,8 +79,8 @@ public final class JdbcActionExecutionRepository implements ActionExecutionRepos
         try {
             long total = PageSupport.count(connection,
                     "SELECT COUNT(*) FROM ordo_action_execution WHERE instance_id = ?", List.of(instanceId));
-            String sql = "SELECT " + COLUMNS + " FROM ordo_action_execution WHERE instance_id = ?"
-                    + " ORDER BY started_at ASC, id ASC LIMIT ? OFFSET ?";
+            String sql = dialect.limit("SELECT " + COLUMNS + " FROM ordo_action_execution WHERE instance_id = ?"
+                    + " ORDER BY started_at ASC, id ASC");
             List<ActionExecution> content = new ArrayList<>();
             try (PreparedStatement select = connection.prepareStatement(sql)) {
                 select.setString(1, instanceId);

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/JdbcApprovalTaskRepository.java

@@ -6,6 +6,8 @@ import com.jetlumen.ordo.api.query.PageRequest;
 import com.jetlumen.ordo.api.query.TaskQuery;
 import com.jetlumen.ordo.api.repository.ApprovalTaskRepository;
 import com.jetlumen.ordo.storage.jdbc.PageSupport.WhereClause;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
 import com.jetlumen.ordo.storage.jdbc.mapper.ApprovalTaskMapper;
 
 import java.sql.Connection;
@@ -47,17 +49,25 @@ public final class JdbcApprovalTaskRepository implements ApprovalTaskRepository
     private static final String CLAIM_IF_DUE =
             "UPDATE ordo_approval_task SET due_at = NULL WHERE id = ? AND status = 'PENDING' AND assignee = ?"
                     + " AND due_at IS NOT NULL AND due_at <= ?";
-    private static final String SELECT_DUE_PENDING =
+    private static final String SELECT_DUE_PENDING_BASE =
             "SELECT " + TASK_COLUMNS + " FROM ordo_approval_task WHERE status = 'PENDING' AND due_at IS NOT NULL"
-                    + " AND due_at <= ? ORDER BY due_at, id LIMIT ?";
+                    + " AND due_at <= ? ORDER BY due_at, id";
     private static final String TASK_COLUMNS_QUALIFIED =
             "t.id, t.instance_id, t.step_id, t.task_name, t.assignee, t.status, t.created_at, t.completed_at,"
                     + " t.action_actor, t.action_comment, t.action_at, t.due_at";
 
     private final JdbcConnectionProvider connectionProvider;
+    private final SqlDialect dialect;
+    private final String selectDuePending;
 
     public JdbcApprovalTaskRepository(JdbcConnectionProvider connectionProvider) {
+        this(connectionProvider, SqlDialects.postgresql());
+    }
+
+    public JdbcApprovalTaskRepository(JdbcConnectionProvider connectionProvider, SqlDialect dialect) {
         this.connectionProvider = Objects.requireNonNull(connectionProvider, "connectionProvider must not be null");
+        this.dialect = Objects.requireNonNull(dialect, "dialect must not be null");
+        this.selectDuePending = dialect.limit(SELECT_DUE_PENDING_BASE, false);
     }
 
     @Override
@@ -153,7 +163,7 @@ public final class JdbcApprovalTaskRepository implements ApprovalTaskRepository
             throw new IllegalArgumentException("limit must be positive");
         }
         Connection connection = connectionProvider.getConnection();
-        try (PreparedStatement select = connection.prepareStatement(SELECT_DUE_PENDING)) {
+        try (PreparedStatement select = connection.prepareStatement(selectDuePending)) {
             select.setTimestamp(1, Timestamp.from(now));
             select.setInt(2, limit);
             try (ResultSet resultSet = select.executeQuery()) {
@@ -197,8 +207,8 @@ public final class JdbcApprovalTaskRepository implements ApprovalTaskRepository
         try {
             long total = PageSupport.count(connection,
                     "SELECT COUNT(*) FROM ordo_approval_task t" + where.sql(), where.params());
-            String sql = "SELECT " + TASK_COLUMNS_QUALIFIED + " FROM ordo_approval_task t" + where.sql()
-                    + " ORDER BY t.created_at DESC, t.id DESC LIMIT ? OFFSET ?";
+            String sql = dialect.limit("SELECT " + TASK_COLUMNS_QUALIFIED + " FROM ordo_approval_task t" + where.sql()
+                    + " ORDER BY t.created_at DESC, t.id DESC");
             List<ApprovalTask> content = new ArrayList<>();
             try (PreparedStatement select = connection.prepareStatement(sql)) {
                 int index = PageSupport.bindParams(select, where.params());

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/JdbcProcessDefinitionRepository.java

@@ -6,6 +6,8 @@ import com.jetlumen.ordo.api.StepTransition;
 import com.jetlumen.ordo.api.query.Page;
 import com.jetlumen.ordo.api.query.PageRequest;
 import com.jetlumen.ordo.api.repository.ProcessDefinitionRepository;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
 import com.jetlumen.ordo.storage.jdbc.mapper.ApprovalStepMapper;
 import com.jetlumen.ordo.storage.jdbc.mapper.ApprovalStepMapper.StepRow;
 import com.jetlumen.ordo.storage.jdbc.mapper.StepTransitionMapper;
@@ -30,8 +32,8 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
             "INSERT INTO ordo_process (id, current_version, name) VALUES (?, ?, ?)";
     private static final String UPDATE_PROCESS =
             "UPDATE ordo_process SET current_version = ?, name = ? WHERE id = ?";
-    private static final String LOCK_PROCESS =
-            "SELECT current_version FROM ordo_process WHERE id = ? FOR UPDATE";
+    private static final String LOCK_PROCESS_BASE =
+            "SELECT current_version FROM ordo_process WHERE id = ?";
     private static final String INSERT_DEFINITION =
             "INSERT INTO ordo_process_definition (id, version, name, created_at) VALUES (?, ?, ?, ?)";
     private static final String INSERT_STEP =
@@ -56,20 +58,32 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
     private static final String SELECT_TRANSITIONS =
             "SELECT from_step_id, to_step_id, condition_key, priority FROM ordo_step_transition "
                     + "WHERE definition_id = ? AND definition_version = ? ORDER BY from_step_id, priority";
-    private static final String SELECT_LATEST_PAGE =
+    private static final String SELECT_LATEST_PAGE_BASE =
             "SELECT p.id, p.current_version, d.name FROM ordo_process p"
                     + " JOIN ordo_process_definition d ON d.id = p.id AND d.version = p.current_version"
-                    + " ORDER BY p.id LIMIT ? OFFSET ?";
+                    + " ORDER BY p.id";
     private static final String COUNT_PROCESSES = "SELECT COUNT(*) FROM ordo_process";
-    private static final String SELECT_VERSIONS_PAGE =
-            "SELECT version, name FROM ordo_process_definition WHERE id = ? ORDER BY version DESC LIMIT ? OFFSET ?";
+    private static final String SELECT_VERSIONS_PAGE_BASE =
+            "SELECT version, name FROM ordo_process_definition WHERE id = ? ORDER BY version DESC";
     private static final String COUNT_VERSIONS =
             "SELECT COUNT(*) FROM ordo_process_definition WHERE id = ?";
 
     private final JdbcConnectionProvider connectionProvider;
+    private final SqlDialect dialect;
+    private final String lockProcess;
+    private final String selectLatestPage;
+    private final String selectVersionsPage;
 
     public JdbcProcessDefinitionRepository(JdbcConnectionProvider connectionProvider) {
+        this(connectionProvider, SqlDialects.postgresql());
+    }
+
+    public JdbcProcessDefinitionRepository(JdbcConnectionProvider connectionProvider, SqlDialect dialect) {
         this.connectionProvider = Objects.requireNonNull(connectionProvider, "connectionProvider must not be null");
+        this.dialect = Objects.requireNonNull(dialect, "dialect must not be null");
+        this.lockProcess = dialect.forUpdate(LOCK_PROCESS_BASE);
+        this.selectLatestPage = dialect.limit(SELECT_LATEST_PAGE_BASE);
+        this.selectVersionsPage = dialect.limit(SELECT_VERSIONS_PAGE_BASE);
     }
 
     @Override
@@ -147,7 +161,7 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
         try {
             long total = PageSupport.count(connection, COUNT_PROCESSES, List.of());
             List<ProcessDefinition> content = new ArrayList<>();
-            try (PreparedStatement select = connection.prepareStatement(SELECT_LATEST_PAGE)) {
+            try (PreparedStatement select = connection.prepareStatement(selectLatestPage)) {
                 select.setInt(1, pageRequest.size());
                 select.setInt(2, pageRequest.offset());
                 List<int[]> versions = new ArrayList<>();
@@ -177,7 +191,7 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
         try {
             long total = PageSupport.count(connection, COUNT_VERSIONS, List.of(definitionId));
             List<Integer> versionNumbers = new ArrayList<>();
-            try (PreparedStatement select = connection.prepareStatement(SELECT_VERSIONS_PAGE)) {
+            try (PreparedStatement select = connection.prepareStatement(selectVersionsPage)) {
                 select.setString(1, definitionId);
                 select.setInt(2, pageRequest.size());
                 select.setInt(3, pageRequest.offset());
@@ -254,8 +268,8 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
         return new ProcessDefinition(definitionId, version, name, steps, transitions);
     }
 
-    private static Integer lockCurrentVersion(Connection connection, String definitionId) throws SQLException {
-        try (PreparedStatement select = connection.prepareStatement(LOCK_PROCESS)) {
+    private Integer lockCurrentVersion(Connection connection, String definitionId) throws SQLException {
+        try (PreparedStatement select = connection.prepareStatement(lockProcess)) {
             select.setString(1, definitionId);
             try (ResultSet resultSet = select.executeQuery()) {
                 return resultSet.next() ? resultSet.getInt("current_version") : null;
@@ -284,7 +298,7 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
         }
     }
 
-    private static boolean insertProcessRow(Connection connection, String id, int version, String name)
+    private boolean insertProcessRow(Connection connection, String id, int version, String name)
             throws SQLException {
         try (PreparedStatement insert = connection.prepareStatement(INSERT_PROCESS)) {
             insert.setString(1, id);
@@ -293,7 +307,7 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
             insert.executeUpdate();
             return true;
         } catch (SQLException e) {
-            if (isDuplicateKey(e)) {
+            if (dialect.isDuplicateKey(e)) {
                 return false;
             }
             throw e;
@@ -370,7 +384,4 @@ public final class JdbcProcessDefinitionRepository implements ProcessDefinitionR
         }
     }
 
-    private static boolean isDuplicateKey(SQLException e) {
-        return "23505".equals(e.getSQLState());
-    }
 }

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/JdbcProcessHistoryRepository.java

@@ -4,6 +4,8 @@ import com.jetlumen.ordo.api.ProcessEvent;
 import com.jetlumen.ordo.api.query.Page;
 import com.jetlumen.ordo.api.query.PageRequest;
 import com.jetlumen.ordo.api.repository.ProcessHistoryRepository;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
 import com.jetlumen.ordo.storage.jdbc.mapper.ProcessEventMapper;
 
 import java.sql.Connection;
@@ -23,9 +25,15 @@ public final class JdbcProcessHistoryRepository implements ProcessHistoryReposit
                     + " VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
 
     private final JdbcConnectionProvider connectionProvider;
+    private final SqlDialect dialect;
 
     public JdbcProcessHistoryRepository(JdbcConnectionProvider connectionProvider) {
+        this(connectionProvider, SqlDialects.postgresql());
+    }
+
+    public JdbcProcessHistoryRepository(JdbcConnectionProvider connectionProvider, SqlDialect dialect) {
         this.connectionProvider = Objects.requireNonNull(connectionProvider, "connectionProvider must not be null");
+        this.dialect = Objects.requireNonNull(dialect, "dialect must not be null");
     }
 
     @Override
@@ -50,8 +58,8 @@ public final class JdbcProcessHistoryRepository implements ProcessHistoryReposit
         try {
             long total = PageSupport.count(connection,
                     "SELECT COUNT(*) FROM ordo_process_event WHERE instance_id = ?", List.of(instanceId));
-            String sql = "SELECT " + COLUMNS + " FROM ordo_process_event WHERE instance_id = ?"
-                    + " ORDER BY occurred_at ASC, id ASC LIMIT ? OFFSET ?";
+            String sql = dialect.limit("SELECT " + COLUMNS + " FROM ordo_process_event WHERE instance_id = ?"
+                    + " ORDER BY occurred_at ASC, id ASC");
             List<ProcessEvent> content = new ArrayList<>();
             try (PreparedStatement select = connection.prepareStatement(sql)) {
                 select.setString(1, instanceId);

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/JdbcProcessInstanceRepository.java

@@ -7,6 +7,8 @@ import com.jetlumen.ordo.api.query.Page;
 import com.jetlumen.ordo.api.query.PageRequest;
 import com.jetlumen.ordo.api.repository.ProcessInstanceRepository;
 import com.jetlumen.ordo.storage.jdbc.PageSupport.WhereClause;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
 import com.jetlumen.ordo.storage.jdbc.mapper.ProcessInstanceMapper;
 
 import java.sql.Connection;
@@ -31,13 +33,21 @@ public final class JdbcProcessInstanceRepository implements ProcessInstanceRepos
     private static final String SELECT_INSTANCE =
             "SELECT id, definition_id, definition_version, initiator, status, context_json, started_at, finished_at"
                     + " FROM ordo_process_instance WHERE id = ?";
-    private static final String EXISTS_RUNNING =
-            "SELECT 1 FROM ordo_process_instance WHERE definition_id = ? AND status = ? LIMIT 1";
+    private static final String EXISTS_RUNNING_BASE =
+            "SELECT 1 FROM ordo_process_instance WHERE definition_id = ? AND status = ?";
 
     private final JdbcConnectionProvider connectionProvider;
+    private final SqlDialect dialect;
+    private final String existsRunning;
 
     public JdbcProcessInstanceRepository(JdbcConnectionProvider connectionProvider) {
+        this(connectionProvider, SqlDialects.postgresql());
+    }
+
+    public JdbcProcessInstanceRepository(JdbcConnectionProvider connectionProvider, SqlDialect dialect) {
         this.connectionProvider = Objects.requireNonNull(connectionProvider, "connectionProvider must not be null");
+        this.dialect = Objects.requireNonNull(dialect, "dialect must not be null");
+        this.existsRunning = dialect.limit(EXISTS_RUNNING_BASE, false);
     }
 
     @Override
@@ -88,9 +98,10 @@ public final class JdbcProcessInstanceRepository implements ProcessInstanceRepos
     @Override
     public boolean existsRunning(String definitionId) {
         Connection connection = connectionProvider.getConnection();
-        try (PreparedStatement select = connection.prepareStatement(EXISTS_RUNNING)) {
+        try (PreparedStatement select = connection.prepareStatement(existsRunning)) {
             select.setString(1, definitionId);
             select.setString(2, ProcessStatus.RUNNING.name());
+            select.setInt(3, 1);
             try (ResultSet resultSet = select.executeQuery()) {
                 return resultSet.next();
             }
@@ -124,9 +135,9 @@ public final class JdbcProcessInstanceRepository implements ProcessInstanceRepos
         try {
             long total = PageSupport.count(connection,
                     "SELECT COUNT(*) FROM ordo_process_instance" + where.sql(), where.params());
-            String sql = "SELECT id, definition_id, definition_version, initiator, status, context_json, started_at,"
-                    + " finished_at FROM ordo_process_instance" + where.sql()
-                    + " ORDER BY started_at DESC, id DESC LIMIT ? OFFSET ?";
+            String sql = dialect.limit("SELECT id, definition_id, definition_version, initiator, status, context_json,"
+                    + " started_at, finished_at FROM ordo_process_instance" + where.sql()
+                    + " ORDER BY started_at DESC, id DESC");
             List<ProcessInstance> content = new ArrayList<>();
             try (PreparedStatement select = connection.prepareStatement(sql)) {
                 int index = PageSupport.bindParams(select, where.params());

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/dialect/LimitOffsetSqlDialect.java

@@ -0,0 +1,19 @@
+package com.jetlumen.ordo.storage.jdbc.dialect;
+
+abstract class LimitOffsetSqlDialect implements SqlDialect {
+
+    @Override
+    public final String limit(String sql) {
+        return limit(sql, true);
+    }
+
+    @Override
+    public final String limit(String sql, boolean offset) {
+        return offset ? sql + " LIMIT ? OFFSET ?" : sql + " LIMIT ?";
+    }
+
+    @Override
+    public final String forUpdate(String sql) {
+        return sql + " FOR UPDATE";
+    }
+}

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/dialect/MysqlSqlDialect.java

@@ -0,0 +1,38 @@
+package com.jetlumen.ordo.storage.jdbc.dialect;
+
+import java.sql.DatabaseMetaData;
+import java.sql.SQLException;
+import java.util.Locale;
+
+/** MySQL / MariaDB (and H2 {@code MODE=MySQL}) dialect. */
+public final class MysqlSqlDialect extends LimitOffsetSqlDialect {
+
+    static final String ID = "mysql";
+
+    @Override
+    public String id() {
+        return ID;
+    }
+
+    @Override
+    public boolean supports(DatabaseMetaData metaData) throws SQLException {
+        String product = metaData.getDatabaseProductName();
+        if (product != null) {
+            String lower = product.toLowerCase(Locale.ROOT);
+            if (lower.contains("mysql") || lower.contains("mariadb")) {
+                return true;
+            }
+        }
+        return PostgresSqlDialect.isH2Mode(metaData, "MYSQL");
+    }
+
+    @Override
+    public boolean isDuplicateKey(SQLException exception) {
+        return "23000".equals(exception.getSQLState()) && exception.getErrorCode() == 1062;
+    }
+
+    @Override
+    public String[] flywayLocations() {
+        return new String[] {"classpath:db/mysql/migration"};
+    }
+}

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/dialect/PostgresSqlDialect.java

@@ -0,0 +1,52 @@
+package com.jetlumen.ordo.storage.jdbc.dialect;
+
+import java.sql.DatabaseMetaData;
+import java.sql.SQLException;
+import java.util.Locale;
+
+/** PostgreSQL (and H2 {@code MODE=PostgreSQL}) dialect. */
+public final class PostgresSqlDialect extends LimitOffsetSqlDialect {
+
+    static final String ID = "postgresql";
+
+    @Override
+    public String id() {
+        return ID;
+    }
+
+    @Override
+    public boolean supports(DatabaseMetaData metaData) throws SQLException {
+        String product = metaData.getDatabaseProductName();
+        if (product != null && product.toLowerCase(Locale.ROOT).contains("postgresql")) {
+            return true;
+        }
+        return isH2Mode(metaData, "POSTGRESQL");
+    }
+
+    @Override
+    public boolean isDuplicateKey(SQLException exception) {
+        return "23505".equals(exception.getSQLState());
+    }
+
+    @Override
+    public String[] flywayLocations() {
+        return new String[] {"classpath:db/postgresql/migration"};
+    }
+
+    static boolean isH2Mode(DatabaseMetaData metaData, String mode) throws SQLException {
+        String product = metaData.getDatabaseProductName();
+        if (product == null || !product.equalsIgnoreCase("H2")) {
+            return false;
+        }
+        String url = metaData.getURL();
+        if (url != null && url.toUpperCase(Locale.ROOT).contains("MODE=" + mode)) {
+            return true;
+        }
+        // H2's DatabaseMetaData.getURL() often omits MODE=; read the runtime setting instead.
+        try (var statement = metaData.getConnection().createStatement();
+             var resultSet = statement.executeQuery(
+                     "SELECT SETTING_VALUE FROM INFORMATION_SCHEMA.SETTINGS WHERE SETTING_NAME = 'MODE'")) {
+            return resultSet.next() && mode.equalsIgnoreCase(resultSet.getString(1));
+        }
+    }
+}

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/dialect/SqlDialect.java

@@ -0,0 +1,29 @@
+package com.jetlumen.ordo.storage.jdbc.dialect;
+
+import java.sql.DatabaseMetaData;
+import java.sql.SQLException;
+
+/**
+ * Database-specific SQL fragments and Flyway locations for JDBC storage.
+ * Additional dialects can be supplied via {@link java.util.ServiceLoader}.
+ */
+public interface SqlDialect {
+
+    String id();
+
+    boolean supports(DatabaseMetaData metaData) throws SQLException;
+
+    boolean isDuplicateKey(SQLException exception);
+
+    /** Appends {@code LIMIT ? OFFSET ?}. */
+    String limit(String sql);
+
+    /**
+     * Appends a row limit. When {@code offset} is {@code true}, also binds {@code OFFSET ?}.
+     */
+    String limit(String sql, boolean offset);
+
+    String forUpdate(String sql);
+
+    String[] flywayLocations();
+}

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/dialect/SqlDialects.java

@@ -0,0 +1,78 @@
+package com.jetlumen.ordo.storage.jdbc.dialect;
+
+import javax.sql.DataSource;
+import java.sql.Connection;
+import java.sql.DatabaseMetaData;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+import java.util.Objects;
+import java.util.ServiceLoader;
+import java.util.stream.Collectors;
+
+/** Loads {@link SqlDialect} implementations and resolves one for a DataSource or explicit id. */
+public final class SqlDialects {
+
+    private SqlDialects() {
+    }
+
+    public static List<SqlDialect> load() {
+        List<SqlDialect> dialects = new ArrayList<>();
+        ServiceLoader.load(SqlDialect.class, SqlDialect.class.getClassLoader()).forEach(dialects::add);
+        if (dialects.isEmpty()) {
+            dialects.add(new PostgresSqlDialect());
+            dialects.add(new MysqlSqlDialect());
+        }
+        return List.copyOf(dialects);
+    }
+
+    public static SqlDialect postgresql() {
+        return new PostgresSqlDialect();
+    }
+
+    public static SqlDialect mysql() {
+        return new MysqlSqlDialect();
+    }
+
+    /**
+     * Resolves a dialect. A non-blank {@code dialectId} wins; otherwise the DataSource metadata
+     * is matched against registered dialects.
+     */
+    public static SqlDialect resolve(DataSource dataSource, String dialectId) {
+        List<SqlDialect> dialects = load();
+        if (dialectId != null && !dialectId.isBlank()) {
+            return byId(dialects, dialectId);
+        }
+        Objects.requireNonNull(dataSource, "dataSource must not be null");
+        try (Connection connection = dataSource.getConnection()) {
+            return detect(dialects, connection.getMetaData());
+        } catch (SQLException e) {
+            throw new IllegalStateException("failed to detect ordo JDBC dialect", e);
+        }
+    }
+
+    static SqlDialect byId(List<SqlDialect> dialects, String dialectId) {
+        String wanted = dialectId.trim().toLowerCase(Locale.ROOT);
+        return dialects.stream()
+                .filter(dialect -> dialect.id().equalsIgnoreCase(wanted))
+                .findFirst()
+                .orElseThrow(() -> new IllegalArgumentException(
+                        "unknown ordo JDBC dialect '" + dialectId + "'; known: " + ids(dialects)));
+    }
+
+    static SqlDialect detect(List<SqlDialect> dialects, DatabaseMetaData metaData) throws SQLException {
+        for (SqlDialect dialect : dialects) {
+            if (dialect.supports(metaData)) {
+                return dialect;
+            }
+        }
+        String product = metaData.getDatabaseProductName();
+        throw new IllegalStateException(
+                "no ordo JDBC dialect for " + product + "; known: " + ids(dialects));
+    }
+
+    private static String ids(List<SqlDialect> dialects) {
+        return dialects.stream().map(SqlDialect::id).collect(Collectors.joining(", "));
+    }
+}

ordo-storage-jdbc/src/main/resources/META-INF/services/com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect

@@ -0,0 +1,2 @@
+com.jetlumen.ordo.storage.jdbc.dialect.PostgresSqlDialect
+com.jetlumen.ordo.storage.jdbc.dialect.MysqlSqlDialect

ordo-storage-jdbc/src/main/resources/db/migration/V1__create_ordo_tables.sql

@@ -1,48 +0,0 @@
--- Ordo approval workflow tables (v1). Target database: PostgreSQL.
--- The DDL sticks to portable types so the same script also runs on H2 in
--- PostgreSQL compatibility mode, which the integration tests use.
-
-CREATE TABLE ordo_process_definition (
-    id   VARCHAR(64)  PRIMARY KEY,
-    name VARCHAR(255) NOT NULL
-);
-
-CREATE TABLE ordo_approval_step (
-    definition_id VARCHAR(64)  NOT NULL,
-    step_id       VARCHAR(64)  NOT NULL,
-    step_name     VARCHAR(255) NOT NULL,
-    assignee      VARCHAR(255) NOT NULL,
-    step_order    INTEGER      NOT NULL,
-    PRIMARY KEY (definition_id, step_id),
-    CONSTRAINT fk_approval_step_definition FOREIGN KEY (definition_id) REFERENCES ordo_process_definition (id)
-);
-
-CREATE TABLE ordo_process_instance (
-    id            VARCHAR(36)  PRIMARY KEY,
-    definition_id VARCHAR(64)  NOT NULL,
-    initiator     VARCHAR(255) NOT NULL,
-    status        VARCHAR(32)  NOT NULL,
-    context_json  TEXT         NOT NULL,
-    started_at    TIMESTAMP    NOT NULL,
-    finished_at   TIMESTAMP,
-    CONSTRAINT fk_process_instance_definition FOREIGN KEY (definition_id) REFERENCES ordo_process_definition (id)
-);
-
-CREATE TABLE ordo_approval_task (
-    id             VARCHAR(36)  PRIMARY KEY,
-    instance_id    VARCHAR(36)  NOT NULL,
-    step_id        VARCHAR(64)  NOT NULL,
-    task_name      VARCHAR(255) NOT NULL,
-    assignee       VARCHAR(255) NOT NULL,
-    status         VARCHAR(32)  NOT NULL,
-    created_at     TIMESTAMP    NOT NULL,
-    completed_at   TIMESTAMP,
-    action_actor   VARCHAR(255),
-    action_comment TEXT,
-    action_at      TIMESTAMP,
-    CONSTRAINT fk_approval_task_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
-);
-
-CREATE INDEX idx_approval_task_instance ON ordo_approval_task (instance_id);
-CREATE INDEX idx_approval_task_status_assignee ON ordo_approval_task (status, assignee);
-CREATE INDEX idx_process_instance_definition ON ordo_process_instance (definition_id);

ordo-storage-jdbc/src/main/resources/db/migration/V2__add_step_candidates_and_policy.sql

@@ -1,23 +0,0 @@
--- Adds multi-candidate (any/all) approval step support.
--- A step no longer has a single fixed assignee; instead it has one or more
--- candidates in ordo_step_candidate, and a policy column decides whether any
--- single candidate approval is enough (ANY) or every candidate must approve (ALL).
-
-ALTER TABLE ordo_approval_step ADD COLUMN policy VARCHAR(16) NOT NULL DEFAULT 'ANY';
-
-CREATE TABLE ordo_step_candidate (
-    definition_id   VARCHAR(64)  NOT NULL,
-    step_id         VARCHAR(64)  NOT NULL,
-    candidate       VARCHAR(255) NOT NULL,
-    candidate_order INTEGER      NOT NULL,
-    PRIMARY KEY (definition_id, step_id, candidate),
-    CONSTRAINT fk_step_candidate_step FOREIGN KEY (definition_id, step_id)
-        REFERENCES ordo_approval_step (definition_id, step_id)
-);
-
--- Migrate any existing single-assignee steps into the new candidate table before
--- the now-unused column is dropped.
-INSERT INTO ordo_step_candidate (definition_id, step_id, candidate, candidate_order)
-SELECT definition_id, step_id, assignee, 0 FROM ordo_approval_step;
-
-ALTER TABLE ordo_approval_step DROP COLUMN assignee;

ordo-storage-jdbc/src/main/resources/db/migration/V3__add_step_transitions.sql

@@ -1,12 +0,0 @@
-CREATE TABLE ordo_step_transition (
-    definition_id VARCHAR(64)  NOT NULL,
-    from_step_id  VARCHAR(64)  NOT NULL,
-    to_step_id    VARCHAR(64),
-    condition_key VARCHAR(255),
-    priority      INTEGER      NOT NULL,
-    PRIMARY KEY (definition_id, from_step_id, priority),
-    CONSTRAINT fk_transition_from FOREIGN KEY (definition_id, from_step_id)
-        REFERENCES ordo_approval_step (definition_id, step_id),
-    CONSTRAINT fk_transition_to FOREIGN KEY (definition_id, to_step_id)
-        REFERENCES ordo_approval_step (definition_id, step_id)
-);

ordo-storage-jdbc/src/main/resources/db/migration/V4__add_step_kind_and_action_key.sql

@@ -1,3 +0,0 @@
--- Adds ACTION step kind and an optional action_key (host ActionHandler lookup).
-ALTER TABLE ordo_approval_step ADD COLUMN kind VARCHAR(16) NOT NULL DEFAULT 'APPROVAL';
-ALTER TABLE ordo_approval_step ADD COLUMN action_key VARCHAR(255);

ordo-storage-jdbc/src/main/resources/db/migration/V5__add_process_event_and_action_execution.sql

@@ -1,29 +0,0 @@
--- Process history events and ACTION-step execution records.
-
-CREATE TABLE ordo_process_event (
-    id           VARCHAR(36)  PRIMARY KEY,
-    instance_id  VARCHAR(36)  NOT NULL,
-    task_id      VARCHAR(36),
-    step_id      VARCHAR(64),
-    event_type   VARCHAR(32)  NOT NULL,
-    actor        VARCHAR(255),
-    detail       TEXT,
-    occurred_at  TIMESTAMP    NOT NULL,
-    CONSTRAINT fk_process_event_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
-);
-
-CREATE INDEX idx_process_event_instance_time ON ordo_process_event (instance_id, occurred_at, id);
-
-CREATE TABLE ordo_action_execution (
-    id             VARCHAR(36)  PRIMARY KEY,
-    instance_id    VARCHAR(36)  NOT NULL,
-    step_id        VARCHAR(64)  NOT NULL,
-    action_key     VARCHAR(255) NOT NULL,
-    status         VARCHAR(32)  NOT NULL,
-    error_message  TEXT,
-    started_at     TIMESTAMP    NOT NULL,
-    finished_at    TIMESTAMP,
-    CONSTRAINT fk_action_execution_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
-);
-
-CREATE INDEX idx_action_execution_instance ON ordo_action_execution (instance_id);

ordo-storage-jdbc/src/main/resources/db/migration/V6__add_step_due.sql

@@ -1,8 +0,0 @@
--- SLA / due escalation: task due_at plus step due policy columns.
-ALTER TABLE ordo_approval_task ADD COLUMN due_at TIMESTAMP;
-CREATE INDEX idx_approval_task_status_due ON ordo_approval_task (status, due_at);
-
-ALTER TABLE ordo_approval_step ADD COLUMN due_after VARCHAR(32);
-ALTER TABLE ordo_approval_step ADD COLUMN due_then VARCHAR(16);
-ALTER TABLE ordo_approval_step ADD COLUMN due_to VARCHAR(255);
-ALTER TABLE ordo_approval_step ADD COLUMN due_action VARCHAR(255);

ordo-storage-jdbc/src/main/resources/db/migration/V7__definition_versions.sql

@@ -1,96 +0,0 @@
-CREATE TABLE ordo_process (
-    id               VARCHAR(64)  PRIMARY KEY,
-    current_version  INTEGER      NOT NULL,
-    name             VARCHAR(255) NOT NULL
-);
-
-INSERT INTO ordo_process (id, current_version, name)
-SELECT id, 1, name FROM ordo_process_definition;
-
-ALTER TABLE ordo_process_instance DROP CONSTRAINT fk_process_instance_definition;
-ALTER TABLE ordo_approval_step DROP CONSTRAINT fk_approval_step_definition;
-ALTER TABLE ordo_step_candidate DROP CONSTRAINT fk_step_candidate_step;
-ALTER TABLE ordo_step_transition DROP CONSTRAINT fk_transition_from;
-ALTER TABLE ordo_step_transition DROP CONSTRAINT fk_transition_to;
-
-CREATE TABLE ordo_process_definition_v7 (
-    id         VARCHAR(64)  NOT NULL,
-    version    INTEGER      NOT NULL,
-    name       VARCHAR(255) NOT NULL,
-    created_at TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
-    PRIMARY KEY (id, version)
-);
-
-INSERT INTO ordo_process_definition_v7 (id, version, name)
-SELECT id, 1, name FROM ordo_process_definition;
-
-DROP TABLE ordo_process_definition;
-ALTER TABLE ordo_process_definition_v7 RENAME TO ordo_process_definition;
-
-CREATE TABLE ordo_approval_step_v7 (
-    definition_id      VARCHAR(64)  NOT NULL,
-    definition_version INTEGER      NOT NULL,
-    step_id            VARCHAR(64)  NOT NULL,
-    step_name          VARCHAR(255) NOT NULL,
-    step_order         INTEGER      NOT NULL,
-    policy             VARCHAR(16)  NOT NULL,
-    kind               VARCHAR(16)  NOT NULL,
-    action_key         VARCHAR(255),
-    due_after          VARCHAR(32),
-    due_then           VARCHAR(16),
-    due_to             VARCHAR(255),
-    due_action         VARCHAR(255),
-    PRIMARY KEY (definition_id, definition_version, step_id),
-    CONSTRAINT fk_approval_step_definition FOREIGN KEY (definition_id, definition_version)
-        REFERENCES ordo_process_definition (id, version)
-);
-
-INSERT INTO ordo_approval_step_v7 (definition_id, definition_version, step_id, step_name, step_order, policy, kind,
-    action_key, due_after, due_then, due_to, due_action)
-SELECT definition_id, 1, step_id, step_name, step_order, policy, kind, action_key, due_after, due_then, due_to,
-    due_action
-FROM ordo_approval_step;
-
-DROP TABLE ordo_approval_step;
-ALTER TABLE ordo_approval_step_v7 RENAME TO ordo_approval_step;
-
-CREATE TABLE ordo_step_candidate_v7 (
-    definition_id      VARCHAR(64)  NOT NULL,
-    definition_version INTEGER      NOT NULL,
-    step_id            VARCHAR(64)  NOT NULL,
-    candidate          VARCHAR(255) NOT NULL,
-    candidate_order    INTEGER      NOT NULL,
-    PRIMARY KEY (definition_id, definition_version, step_id, candidate),
-    CONSTRAINT fk_step_candidate_step FOREIGN KEY (definition_id, definition_version, step_id)
-        REFERENCES ordo_approval_step (definition_id, definition_version, step_id)
-);
-
-INSERT INTO ordo_step_candidate_v7 (definition_id, definition_version, step_id, candidate, candidate_order)
-SELECT definition_id, 1, step_id, candidate, candidate_order FROM ordo_step_candidate;
-
-DROP TABLE ordo_step_candidate;
-ALTER TABLE ordo_step_candidate_v7 RENAME TO ordo_step_candidate;
-
-CREATE TABLE ordo_step_transition_v7 (
-    definition_id      VARCHAR(64)  NOT NULL,
-    definition_version INTEGER      NOT NULL,
-    from_step_id       VARCHAR(64)  NOT NULL,
-    to_step_id         VARCHAR(64),
-    condition_key      VARCHAR(255),
-    priority           INTEGER      NOT NULL,
-    PRIMARY KEY (definition_id, definition_version, from_step_id, priority),
-    CONSTRAINT fk_transition_from FOREIGN KEY (definition_id, definition_version, from_step_id)
-        REFERENCES ordo_approval_step (definition_id, definition_version, step_id),
-    CONSTRAINT fk_transition_to FOREIGN KEY (definition_id, definition_version, to_step_id)
-        REFERENCES ordo_approval_step (definition_id, definition_version, step_id)
-);
-
-INSERT INTO ordo_step_transition_v7 (definition_id, definition_version, from_step_id, to_step_id, condition_key, priority)
-SELECT definition_id, 1, from_step_id, to_step_id, condition_key, priority FROM ordo_step_transition;
-
-DROP TABLE ordo_step_transition;
-ALTER TABLE ordo_step_transition_v7 RENAME TO ordo_step_transition;
-
-ALTER TABLE ordo_process_instance ADD COLUMN definition_version INTEGER DEFAULT 1 NOT NULL;
-ALTER TABLE ordo_process_instance ADD CONSTRAINT fk_process_instance_definition
-    FOREIGN KEY (definition_id, definition_version) REFERENCES ordo_process_definition (id, version);

ordo-storage-jdbc/src/main/resources/db/mysql/migration/V1__baseline.sql

@@ -0,0 +1,125 @@
+-- Ordo schema baseline (MySQL / MariaDB).
+
+CREATE TABLE ordo_process (
+    id               VARCHAR(64)  NOT NULL,
+    current_version  INTEGER      NOT NULL,
+    name             VARCHAR(255) NOT NULL,
+    PRIMARY KEY (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE ordo_process_definition (
+    id         VARCHAR(64)  NOT NULL,
+    version    INTEGER      NOT NULL,
+    name       VARCHAR(255) NOT NULL,
+    created_at DATETIME(3)  NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+    PRIMARY KEY (id, version)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE ordo_approval_step (
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    step_id            VARCHAR(64)  NOT NULL,
+    step_name          VARCHAR(255) NOT NULL,
+    step_order         INTEGER      NOT NULL,
+    policy             VARCHAR(16)  NOT NULL,
+    kind               VARCHAR(16)  NOT NULL,
+    action_key         VARCHAR(255),
+    due_after          VARCHAR(32),
+    due_then           VARCHAR(16),
+    due_to             VARCHAR(255),
+    due_action         VARCHAR(255),
+    PRIMARY KEY (definition_id, definition_version, step_id),
+    CONSTRAINT fk_approval_step_definition FOREIGN KEY (definition_id, definition_version)
+        REFERENCES ordo_process_definition (id, version)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE ordo_step_candidate (
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    step_id            VARCHAR(64)  NOT NULL,
+    candidate          VARCHAR(255) NOT NULL,
+    candidate_order    INTEGER      NOT NULL,
+    PRIMARY KEY (definition_id, definition_version, step_id, candidate),
+    CONSTRAINT fk_step_candidate_step FOREIGN KEY (definition_id, definition_version, step_id)
+        REFERENCES ordo_approval_step (definition_id, definition_version, step_id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE ordo_step_transition (
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    from_step_id       VARCHAR(64)  NOT NULL,
+    to_step_id         VARCHAR(64),
+    condition_key      VARCHAR(255),
+    priority           INTEGER      NOT NULL,
+    PRIMARY KEY (definition_id, definition_version, from_step_id, priority),
+    CONSTRAINT fk_transition_from FOREIGN KEY (definition_id, definition_version, from_step_id)
+        REFERENCES ordo_approval_step (definition_id, definition_version, step_id),
+    CONSTRAINT fk_transition_to FOREIGN KEY (definition_id, definition_version, to_step_id)
+        REFERENCES ordo_approval_step (definition_id, definition_version, step_id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE ordo_process_instance (
+    id                 VARCHAR(36)  NOT NULL,
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    initiator          VARCHAR(255) NOT NULL,
+    status             VARCHAR(32)  NOT NULL,
+    context_json       TEXT         NOT NULL,
+    started_at         DATETIME(3)  NOT NULL,
+    finished_at        DATETIME(3),
+    PRIMARY KEY (id),
+    CONSTRAINT fk_process_instance_definition FOREIGN KEY (definition_id, definition_version)
+        REFERENCES ordo_process_definition (id, version)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE ordo_approval_task (
+    id             VARCHAR(36)  NOT NULL,
+    instance_id    VARCHAR(36)  NOT NULL,
+    step_id        VARCHAR(64)  NOT NULL,
+    task_name      VARCHAR(255) NOT NULL,
+    assignee       VARCHAR(255) NOT NULL,
+    status         VARCHAR(32)  NOT NULL,
+    created_at     DATETIME(3)  NOT NULL,
+    completed_at   DATETIME(3),
+    action_actor   VARCHAR(255),
+    action_comment TEXT,
+    action_at      DATETIME(3),
+    due_at         DATETIME(3),
+    PRIMARY KEY (id),
+    CONSTRAINT fk_approval_task_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE INDEX idx_approval_task_instance ON ordo_approval_task (instance_id);
+CREATE INDEX idx_approval_task_status_assignee ON ordo_approval_task (status, assignee);
+CREATE INDEX idx_approval_task_status_due ON ordo_approval_task (status, due_at);
+CREATE INDEX idx_process_instance_definition ON ordo_process_instance (definition_id);
+
+CREATE TABLE ordo_process_event (
+    id           VARCHAR(36)  NOT NULL,
+    instance_id  VARCHAR(36)  NOT NULL,
+    task_id      VARCHAR(36),
+    step_id      VARCHAR(64),
+    event_type   VARCHAR(32)  NOT NULL,
+    actor        VARCHAR(255),
+    detail       TEXT,
+    occurred_at  DATETIME(3)  NOT NULL,
+    PRIMARY KEY (id),
+    CONSTRAINT fk_process_event_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE INDEX idx_process_event_instance_time ON ordo_process_event (instance_id, occurred_at, id);
+
+CREATE TABLE ordo_action_execution (
+    id             VARCHAR(36)  NOT NULL,
+    instance_id    VARCHAR(36)  NOT NULL,
+    step_id        VARCHAR(64)  NOT NULL,
+    action_key     VARCHAR(255) NOT NULL,
+    status         VARCHAR(32)  NOT NULL,
+    error_message  TEXT,
+    started_at     DATETIME(3)  NOT NULL,
+    finished_at    DATETIME(3),
+    PRIMARY KEY (id),
+    CONSTRAINT fk_action_execution_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE INDEX idx_action_execution_instance ON ordo_action_execution (instance_id);

ordo-storage-jdbc/src/main/resources/db/postgresql/migration/V1__baseline.sql

@@ -0,0 +1,120 @@
+-- Ordo schema baseline (PostgreSQL / H2 MODE=PostgreSQL).
+
+CREATE TABLE ordo_process (
+    id               VARCHAR(64)  PRIMARY KEY,
+    current_version  INTEGER      NOT NULL,
+    name             VARCHAR(255) NOT NULL
+);
+
+CREATE TABLE ordo_process_definition (
+    id         VARCHAR(64)  NOT NULL,
+    version    INTEGER      NOT NULL,
+    name       VARCHAR(255) NOT NULL,
+    created_at TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (id, version)
+);
+
+CREATE TABLE ordo_approval_step (
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    step_id            VARCHAR(64)  NOT NULL,
+    step_name          VARCHAR(255) NOT NULL,
+    step_order         INTEGER      NOT NULL,
+    policy             VARCHAR(16)  NOT NULL,
+    kind               VARCHAR(16)  NOT NULL,
+    action_key         VARCHAR(255),
+    due_after          VARCHAR(32),
+    due_then           VARCHAR(16),
+    due_to             VARCHAR(255),
+    due_action         VARCHAR(255),
+    PRIMARY KEY (definition_id, definition_version, step_id),
+    CONSTRAINT fk_approval_step_definition FOREIGN KEY (definition_id, definition_version)
+        REFERENCES ordo_process_definition (id, version)
+);
+
+CREATE TABLE ordo_step_candidate (
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    step_id            VARCHAR(64)  NOT NULL,
+    candidate          VARCHAR(255) NOT NULL,
+    candidate_order    INTEGER      NOT NULL,
+    PRIMARY KEY (definition_id, definition_version, step_id, candidate),
+    CONSTRAINT fk_step_candidate_step FOREIGN KEY (definition_id, definition_version, step_id)
+        REFERENCES ordo_approval_step (definition_id, definition_version, step_id)
+);
+
+CREATE TABLE ordo_step_transition (
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    from_step_id       VARCHAR(64)  NOT NULL,
+    to_step_id         VARCHAR(64),
+    condition_key      VARCHAR(255),
+    priority           INTEGER      NOT NULL,
+    PRIMARY KEY (definition_id, definition_version, from_step_id, priority),
+    CONSTRAINT fk_transition_from FOREIGN KEY (definition_id, definition_version, from_step_id)
+        REFERENCES ordo_approval_step (definition_id, definition_version, step_id),
+    CONSTRAINT fk_transition_to FOREIGN KEY (definition_id, definition_version, to_step_id)
+        REFERENCES ordo_approval_step (definition_id, definition_version, step_id)
+);
+
+CREATE TABLE ordo_process_instance (
+    id                 VARCHAR(36)  PRIMARY KEY,
+    definition_id      VARCHAR(64)  NOT NULL,
+    definition_version INTEGER      NOT NULL,
+    initiator          VARCHAR(255) NOT NULL,
+    status             VARCHAR(32)  NOT NULL,
+    context_json       TEXT         NOT NULL,
+    started_at         TIMESTAMP    NOT NULL,
+    finished_at        TIMESTAMP,
+    CONSTRAINT fk_process_instance_definition FOREIGN KEY (definition_id, definition_version)
+        REFERENCES ordo_process_definition (id, version)
+);
+
+CREATE TABLE ordo_approval_task (
+    id             VARCHAR(36)  PRIMARY KEY,
+    instance_id    VARCHAR(36)  NOT NULL,
+    step_id        VARCHAR(64)  NOT NULL,
+    task_name      VARCHAR(255) NOT NULL,
+    assignee       VARCHAR(255) NOT NULL,
+    status         VARCHAR(32)  NOT NULL,
+    created_at     TIMESTAMP    NOT NULL,
+    completed_at   TIMESTAMP,
+    action_actor   VARCHAR(255),
+    action_comment TEXT,
+    action_at      TIMESTAMP,
+    due_at         TIMESTAMP,
+    CONSTRAINT fk_approval_task_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
+);
+
+CREATE INDEX idx_approval_task_instance ON ordo_approval_task (instance_id);
+CREATE INDEX idx_approval_task_status_assignee ON ordo_approval_task (status, assignee);
+CREATE INDEX idx_approval_task_status_due ON ordo_approval_task (status, due_at);
+CREATE INDEX idx_process_instance_definition ON ordo_process_instance (definition_id);
+
+CREATE TABLE ordo_process_event (
+    id           VARCHAR(36)  PRIMARY KEY,
+    instance_id  VARCHAR(36)  NOT NULL,
+    task_id      VARCHAR(36),
+    step_id      VARCHAR(64),
+    event_type   VARCHAR(32)  NOT NULL,
+    actor        VARCHAR(255),
+    detail       TEXT,
+    occurred_at  TIMESTAMP    NOT NULL,
+    CONSTRAINT fk_process_event_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
+);
+
+CREATE INDEX idx_process_event_instance_time ON ordo_process_event (instance_id, occurred_at, id);
+
+CREATE TABLE ordo_action_execution (
+    id             VARCHAR(36)  PRIMARY KEY,
+    instance_id    VARCHAR(36)  NOT NULL,
+    step_id        VARCHAR(64)  NOT NULL,
+    action_key     VARCHAR(255) NOT NULL,
+    status         VARCHAR(32)  NOT NULL,
+    error_message  TEXT,
+    started_at     TIMESTAMP    NOT NULL,
+    finished_at    TIMESTAMP,
+    CONSTRAINT fk_action_execution_instance FOREIGN KEY (instance_id) REFERENCES ordo_process_instance (id)
+);
+
+CREATE INDEX idx_action_execution_instance ON ordo_action_execution (instance_id);

ordo-storage-jdbc/src/test/java/com/jetlumen/ordo/storage/jdbc/JdbcMysqlIntegrationTest.java

@@ -0,0 +1,282 @@
+package com.jetlumen.ordo.storage.jdbc;
+
+import com.jetlumen.ordo.api.ActionHandler;
+import com.jetlumen.ordo.api.ApprovalStep;
+import com.jetlumen.ordo.api.ApprovalTask;
+import com.jetlumen.ordo.api.AssigneeResolver;
+import com.jetlumen.ordo.api.OrdoEngine;
+import com.jetlumen.ordo.api.ProcessContext;
+import com.jetlumen.ordo.api.ProcessDefinition;
+import com.jetlumen.ordo.api.ProcessInstance;
+import com.jetlumen.ordo.api.ProcessStatus;
+import com.jetlumen.ordo.api.RoutingCondition;
+import com.jetlumen.ordo.api.TaskAction;
+import com.jetlumen.ordo.api.TaskStatus;
+import com.jetlumen.ordo.core.DefaultOrdoEngine;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialect;
+import com.jetlumen.ordo.storage.jdbc.dialect.SqlDialects;
+import com.mysql.cj.jdbc.MysqlDataSource;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.Assumptions;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import javax.sql.DataSource;
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.time.Clock;
+import java.time.Instant;
+import java.time.ZoneOffset;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Optional MySQL counterpart of {@link JdbcPostgresIntegrationTest}.
+ *
+ * <p>Configured with {@code -Dordo.test.mysql.*} or {@code ORDO_TEST_MYSQL_*};
+ * defaults {@code localhost:3306}, user/password {@code root}. Skipped when
+ * MySQL is unreachable.
+ */
+class JdbcMysqlIntegrationTest {
+    private static final String DATABASE = "ordo_test";
+    private static final Instant NOW = Instant.parse("2026-03-03T10:00:00Z");
+    private static final SqlDialect DIALECT = SqlDialects.mysql();
+
+    private static DataSource dataSource;
+    private JdbcConnectionProvider connectionProvider;
+
+    @BeforeAll
+    static void setUpDatabase() throws SQLException {
+        MysqlDataSource rootDataSource = newDataSource("");
+        String reachabilityProblem = null;
+        try (Connection ignored = rootDataSource.getConnection()) {
+            // probe
+        } catch (SQLException e) {
+            reachabilityProblem = e.getMessage();
+        }
+        Assumptions.assumeTrue(reachabilityProblem == null,
+                "MySQL not reachable at " + config("ordo.test.mysql.host", "ORDO_TEST_MYSQL_HOST", "localhost")
+                        + ":" + config("ordo.test.mysql.port", "ORDO_TEST_MYSQL_PORT", "3306")
+                        + " — skipping MySQL integration tests (" + reachabilityProblem + ")");
+
+        try (Connection connection = rootDataSource.getConnection(); Statement statement = connection.createStatement()) {
+            statement.execute("DROP DATABASE IF EXISTS " + DATABASE);
+            statement.execute("CREATE DATABASE " + DATABASE + " CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci");
+        }
+
+        MysqlDataSource schemaDataSource = newDataSource(DATABASE);
+        JdbcTestSupport.applySchema(schemaDataSource, JdbcTestSupport.MYSQL_BASELINE);
+        dataSource = schemaDataSource;
+    }
+
+    @AfterAll
+    static void tearDownDatabase() {
+        if (dataSource == null) {
+            return;
+        }
+        MysqlDataSource rootDataSource = newDataSource("");
+        try (Connection connection = rootDataSource.getConnection(); Statement statement = connection.createStatement()) {
+            statement.execute("DROP DATABASE IF EXISTS " + DATABASE);
+        } catch (SQLException e) {
+            // leftover ordo_test is dropped on the next run
+        }
+    }
+
+    @BeforeEach
+    void setUp() {
+        connectionProvider = new JdbcConnectionProvider(dataSource);
+    }
+
+    @Test
+    void engineCompletesASequentialApprovalProcessOverMysql() {
+        OrdoEngine engine = newEngine(AssigneeResolver.direct());
+        engine.publish(ProcessDefinition.linear("leave-mysql", "Leave request", List.of(
+                ApprovalStep.single("manager", "Manager approval", "maria"),
+                ApprovalStep.single("hr", "HR approval", "henry"))));
+
+        ProcessInstance instance = engine.start("leave-mysql", "alice",
+                new ProcessContext(Map.of("requestId", "LEAVE-2026-001", "days", 5)));
+        ApprovalTask managerTask = engine.findPendingTasksByInstanceId(instance.id()).get(0);
+        engine.approve(managerTask.id(), "maria", "ok");
+        ApprovalTask hrTask = engine.findPendingTasksByInstanceId(instance.id()).get(0);
+        engine.approve(hrTask.id(), "henry", "ok");
+
+        ProcessInstance finished = engine.findInstance(instance.id()).orElseThrow();
+        assertEquals(ProcessStatus.APPROVED, finished.status());
+        assertEquals(NOW, finished.finishedAt());
+        assertEquals("LEAVE-2026-001", finished.context().value("requestId").orElseThrow());
+    }
+
+    @Test
+    void publishIsIdempotentForTheSameGraphAndVersionsAChangedGraph() {
+        JdbcProcessDefinitionRepository repository =
+                new JdbcProcessDefinitionRepository(connectionProvider, DIALECT);
+        ProcessDefinition definition = ProcessDefinition.linear("leave-dup-mysql", "Leave request",
+                List.of(ApprovalStep.single("manager", "Manager approval", "maria")));
+
+        assertEquals(1, repository.publish(definition).version());
+        assertEquals(1, repository.publish(definition).version());
+        assertEquals(2, repository.publish(ProcessDefinition.linear("leave-dup-mysql", "Second attempt",
+                List.of(ApprovalStep.single("manager", "Manager approval", "maria")))).version());
+        assertEquals("Second attempt", repository.findLatest("leave-dup-mysql").orElseThrow().name());
+        assertEquals("Leave request", repository.find("leave-dup-mysql", 1).orElseThrow().name());
+    }
+
+    @Test
+    void rejectsDuplicateInstanceIdsViaTheDatabaseUniqueConstraint() {
+        new JdbcProcessDefinitionRepository(connectionProvider, DIALECT).publish(ProcessDefinition.linear(
+                "leave-dup-inst-mysql", "Leave request",
+                List.of(ApprovalStep.single("manager", "Manager approval", "maria"))));
+        JdbcProcessInstanceRepository repository =
+                new JdbcProcessInstanceRepository(connectionProvider, DIALECT);
+        ProcessInstance instance = new ProcessInstance("inst-dup-mysql", "leave-dup-inst-mysql", 1, "alice",
+                ProcessStatus.RUNNING, NOW, null, ProcessContext.empty());
+        repository.insert(instance);
+
+        assertThrows(JdbcStorageException.class, () -> repository.insert(instance));
+    }
+
+    @Test
+    void storesTimestampsAtMillisecondPrecision() {
+        new JdbcProcessDefinitionRepository(connectionProvider, DIALECT).publish(ProcessDefinition.linear(
+                "leave-time-mysql", "Leave request",
+                List.of(ApprovalStep.single("manager", "Manager approval", "maria"))));
+        JdbcProcessInstanceRepository repository =
+                new JdbcProcessInstanceRepository(connectionProvider, DIALECT);
+
+        Instant milliAligned = Instant.parse("2026-01-15T09:00:00.123Z");
+        repository.insert(new ProcessInstance("inst-time-1", "leave-time-mysql", 1, "alice",
+                ProcessStatus.RUNNING, milliAligned, null, ProcessContext.empty()));
+        assertEquals(milliAligned, repository.findById("inst-time-1").orElseThrow().startedAt());
+
+        Instant withMicros = Instant.parse("2026-01-15T09:00:00.123456Z");
+        repository.insert(new ProcessInstance("inst-time-2", "leave-time-mysql", 1, "alice",
+                ProcessStatus.RUNNING, withMicros, null, ProcessContext.empty()));
+        assertEquals(milliAligned, repository.findById("inst-time-2").orElseThrow().startedAt());
+    }
+
+    @Test
+    void onlyOneOfTwoConcurrentCompletionsWinsOnMysql() throws Exception {
+        new JdbcProcessDefinitionRepository(connectionProvider, DIALECT).publish(ProcessDefinition.linear(
+                "leave-race-mysql", "Leave request",
+                List.of(ApprovalStep.single("manager", "Manager approval", "maria"))));
+        JdbcProcessInstanceRepository instanceRepository =
+                new JdbcProcessInstanceRepository(connectionProvider, DIALECT);
+        instanceRepository.insert(new ProcessInstance("inst-race-mysql", "leave-race-mysql", 1, "alice",
+                ProcessStatus.RUNNING, NOW, null, ProcessContext.empty()));
+
+        JdbcApprovalTaskRepository taskRepository =
+                new JdbcApprovalTaskRepository(connectionProvider, DIALECT);
+        ApprovalTask pending = new ApprovalTask("task-race-mysql", "inst-race-mysql", "manager",
+                "Manager approval", "maria", TaskStatus.PENDING, NOW, null, null, null);
+        taskRepository.save(pending);
+        Instant completedAt = NOW.plusSeconds(30);
+
+        CountDownLatch start = new CountDownLatch(1);
+        CountDownLatch done = new CountDownLatch(2);
+        AtomicInteger wins = new AtomicInteger();
+        Thread first = new Thread(() -> attempt(start, done, wins, completedTask(pending, "first", completedAt),
+                taskRepository));
+        Thread second = new Thread(() -> attempt(start, done, wins, completedTask(pending, "second", completedAt),
+                taskRepository));
+        first.start();
+        second.start();
+        start.countDown();
+
+        assertTrue(done.await(10, TimeUnit.SECONDS));
+        assertEquals(1, wins.get());
+        ApprovalTask stored = taskRepository.findById("task-race-mysql").orElseThrow();
+        assertEquals("maria", stored.action().actor());
+        assertTrue(Set.of("first", "second").contains(stored.action().comment()));
+    }
+
+    @Test
+    void rollsBackTheWholeApprovalWhenTheNextStepCannotBeCreated() {
+        OrdoEngine failingEngine = newEngine((candidate, step, context) -> {
+            if (step.id().equals("hr")) {
+                throw new IllegalStateException("no hr approval today");
+            }
+            return candidate;
+        });
+        failingEngine.publish(ProcessDefinition.linear("leave-rollback-mysql", "Leave request", List.of(
+                ApprovalStep.single("manager", "Manager approval", "maria"),
+                ApprovalStep.single("hr", "HR approval", "henry"))));
+
+        ProcessInstance instance = failingEngine.start("leave-rollback-mysql", "alice");
+        ApprovalTask managerTask = failingEngine.findPendingTasksByInstanceId(instance.id()).get(0);
+        assertThrows(IllegalStateException.class, () -> failingEngine.approve(managerTask.id(), "maria"));
+
+        ApprovalTask storedTask = failingEngine.findTask(managerTask.id()).orElseThrow();
+        assertEquals(TaskStatus.PENDING, storedTask.status());
+        assertNull(storedTask.action());
+        assertEquals(1, failingEngine.findTasks(instance.id()).size());
+        assertEquals(ProcessStatus.RUNNING, failingEngine.findInstance(instance.id()).orElseThrow().status());
+    }
+
+    private OrdoEngine newEngine(AssigneeResolver assigneeResolver) {
+        return new DefaultOrdoEngine(Clock.fixed(NOW, ZoneOffset.UTC), assigneeResolver, RoutingCondition.always(),
+                ActionHandler.noop(),
+                new JdbcTransactionExecutor(connectionProvider),
+                new JdbcProcessDefinitionRepository(connectionProvider, DIALECT),
+                new JdbcProcessInstanceRepository(connectionProvider, DIALECT),
+                new JdbcApprovalTaskRepository(connectionProvider, DIALECT),
+                new JdbcProcessHistoryRepository(connectionProvider, DIALECT),
+                new JdbcActionExecutionRepository(connectionProvider, DIALECT),
+                List.of());
+    }
+
+    private static MysqlDataSource newDataSource(String database) {
+        MysqlDataSource mysqlDataSource = new MysqlDataSource();
+        String host = config("ordo.test.mysql.host", "ORDO_TEST_MYSQL_HOST", "localhost");
+        String port = config("ordo.test.mysql.port", "ORDO_TEST_MYSQL_PORT", "3306");
+        String databasePath = database.isEmpty() ? "/" : "/" + database;
+        mysqlDataSource.setUrl("jdbc:mysql://" + host + ":" + port + databasePath
+                + "?allowPublicKeyRetrieval=true&sslMode=DISABLED&characterEncoding=utf8");
+        mysqlDataSource.setUser(config("ordo.test.mysql.user", "ORDO_TEST_MYSQL_USER", "root"));
+        mysqlDataSource.setPassword(config("ordo.test.mysql.password", "ORDO_TEST_MYSQL_PASSWORD", "root"));
+        return mysqlDataSource;
+    }
+
+    private static String config(String property, String env, String defaultValue) {
+        String fromProperty = System.getProperty(property);
+        if (fromProperty != null && !fromProperty.isBlank()) {
+            return fromProperty;
+        }
+        String fromEnv = System.getenv(env);
+        if (fromEnv != null && !fromEnv.isBlank()) {
+            return fromEnv;
+        }
+        return defaultValue;
+    }
+
+    private static void attempt(CountDownLatch start, CountDownLatch done, AtomicInteger wins,
+                                ApprovalTask completed, JdbcApprovalTaskRepository repository) {
+        try {
+            start.await();
+            if (repository.completeIfPending(completed)) {
+                wins.incrementAndGet();
+            }
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        } finally {
+            done.countDown();
+        }
+    }
+
+    private static ApprovalTask completedTask(ApprovalTask pending, String comment, Instant completedAt) {
+        return new ApprovalTask(pending.id(), pending.instanceId(), pending.stepId(), pending.name(),
+                pending.assignee(), TaskStatus.APPROVED, pending.createdAt(), completedAt,
+                new TaskAction(pending.assignee(), comment, completedAt), pending.dueAt());
+    }
+}

ordo-storage-jdbc/src/test/java/com/jetlumen/ordo/storage/jdbc/JdbcPostgresIntegrationTest.java

@@ -49,7 +49,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * ({@code -Dordo.test.pg.host=myhost}) or environment variables
  * ({@code ORDO_TEST_PG_HOST}); defaults assume {@code localhost:5432} with
  * database/user/password {@code postgres}. Each run creates a dedicated
- * {@code ordo_test} schema, applies the V1 migration there and drops it
+ * {@code ordo_test} schema, applies the PostgreSQL baseline there and drops it
  * afterward, so the rest of the database stays untouched. The class is
  * skipped when the database cannot be reached.
  */

ordo-storage-jdbc/src/test/java/com/jetlumen/ordo/storage/jdbc/JdbcTestSupport.java

@@ -13,16 +13,8 @@ import java.util.UUID;
 
 /** Creates isolated in-memory H2 databases with the Ordo schema applied. */
 final class JdbcTestSupport {
-    private static final String[] MIGRATIONS = {
-            "/db/migration/V1__create_ordo_tables.sql",
-            "/db/migration/V2__add_step_candidates_and_policy.sql",
-            "/db/migration/V3__add_step_transitions.sql",
-            "/db/migration/V4__add_step_kind_and_action_key.sql",
-            "/db/migration/V5__add_process_event_and_action_execution.sql",
-            "/db/migration/V6__add_step_due.sql",
-            "/db/migration/V7__definition_versions.sql"
-    };
-    private static final String[] SCHEMA_SQL = loadSchemas();
+    static final String POSTGRES_BASELINE = "/db/postgresql/migration/V1__baseline.sql";
+    static final String MYSQL_BASELINE = "/db/mysql/migration/V1__baseline.sql";
 
     private JdbcTestSupport() {
     }
@@ -36,14 +28,16 @@ final class JdbcTestSupport {
         return dataSource;
     }
 
-    /** Applies every migration script in order to an empty database, e.g. a PostgreSQL test container. */
     static void applySchema(DataSource dataSource) {
+        applySchema(dataSource, POSTGRES_BASELINE);
+    }
+
+    static void applySchema(DataSource dataSource, String resourcePath) {
+        String migration = loadSchema(resourcePath);
         try (Connection connection = dataSource.getConnection(); Statement statement = connection.createStatement()) {
-            for (String migration : SCHEMA_SQL) {
-                for (String sql : stripComments(migration).split(";")) {
-                    if (!sql.isBlank()) {
-                        statement.execute(sql);
-                    }
+            for (String sql : stripComments(migration).split(";")) {
+                if (!sql.isBlank()) {
+                    statement.execute(sql);
                 }
             }
         } catch (SQLException e) {
@@ -64,14 +58,6 @@ final class JdbcTestSupport {
         return result.toString();
     }
 
-    private static String[] loadSchemas() {
-        String[] schemas = new String[MIGRATIONS.length];
-        for (int i = 0; i < MIGRATIONS.length; i++) {
-            schemas[i] = loadSchema(MIGRATIONS[i]);
-        }
-        return schemas;
-    }
-
     private static String loadSchema(String resourcePath) {
         try (InputStream input = JdbcTestSupport.class.getResourceAsStream(resourcePath)) {
             if (input == null) {
@@ -83,4 +69,3 @@ final class JdbcTestSupport {
         }
     }
 }
-

ordo-storage-jdbc/src/test/java/com/jetlumen/ordo/storage/jdbc/dialect/SqlDialectsTest.java

@@ -0,0 +1,68 @@
+package com.jetlumen.ordo.storage.jdbc.dialect;
+
+import org.h2.jdbcx.JdbcDataSource;
+import org.junit.jupiter.api.Test;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.UUID;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class SqlDialectsTest {
+
+    @Test
+    void loadRegistersBuiltInDialects() {
+        assertTrue(SqlDialects.load().stream().anyMatch(d -> d.id().equals("postgresql")));
+        assertTrue(SqlDialects.load().stream().anyMatch(d -> d.id().equals("mysql")));
+    }
+
+    @Test
+    void resolveByIdIgnoresDataSource() {
+        assertEquals("mysql", SqlDialects.resolve(null, "MySQL").id());
+        assertEquals("postgresql", SqlDialects.resolve(null, "postgresql").id());
+    }
+
+    @Test
+    void unknownIdListsKnownDialects() {
+        IllegalArgumentException ex = assertThrows(IllegalArgumentException.class,
+                () -> SqlDialects.resolve(null, "oracle"));
+        assertTrue(ex.getMessage().contains("oracle"));
+        assertTrue(ex.getMessage().contains("postgresql"));
+        assertTrue(ex.getMessage().contains("mysql"));
+    }
+
+    @Test
+    void detectsH2PostgreSQLMode() throws SQLException {
+        JdbcDataSource dataSource = new JdbcDataSource();
+        dataSource.setURL("jdbc:h2:mem:dialect_" + UUID.randomUUID()
+                + ";MODE=PostgreSQL;DATABASE_TO_LOWER=TRUE;DB_CLOSE_DELAY=-1");
+        dataSource.setUser("sa");
+        try (Connection ignored = dataSource.getConnection()) {
+            assertEquals("postgresql", SqlDialects.resolve(dataSource, null).id());
+        }
+    }
+
+    @Test
+    void postgresDuplicateKeyIsSqlState23505() {
+        PostgresSqlDialect dialect = new PostgresSqlDialect();
+        assertTrue(dialect.isDuplicateKey(new SQLException("dup", "23505")));
+        assertFalse(dialect.isDuplicateKey(new SQLException("dup", "23000", 1062)));
+        assertEquals("SELECT 1 LIMIT ? OFFSET ?", dialect.limit("SELECT 1"));
+        assertEquals("SELECT 1 LIMIT ?", dialect.limit("SELECT 1", false));
+        assertEquals("SELECT 1 FOR UPDATE", dialect.forUpdate("SELECT 1"));
+        assertEquals("classpath:db/postgresql/migration", dialect.flywayLocations()[0]);
+    }
+
+    @Test
+    void mysqlDuplicateKeyIsSqlState23000AndError1062() {
+        MysqlSqlDialect dialect = new MysqlSqlDialect();
+        assertTrue(dialect.isDuplicateKey(new SQLException("dup", "23000", 1062)));
+        assertFalse(dialect.isDuplicateKey(new SQLException("fk", "23000", 1452)));
+        assertFalse(dialect.isDuplicateKey(new SQLException("dup", "23505")));
+        assertEquals("classpath:db/mysql/migration", dialect.flywayLocations()[0]);
+    }
+}

pom.xml

@@ -30,6 +30,7 @@
         <jackson.version>2.18.2</jackson.version>
         <h2.version>2.3.232</h2.version>
         <postgresql.version>42.7.5</postgresql.version>
+        <mysql.version>8.4.0</mysql.version>
     </properties>
 
     <dependencyManagement>
@@ -54,6 +55,11 @@
                 <artifactId>postgresql</artifactId>
                 <version>${postgresql.version}</version>
             </dependency>
+            <dependency>
+                <groupId>com.mysql</groupId>
+                <artifactId>mysql-connector-j</artifactId>
+                <version>${mysql.version}</version>
+            </dependency>
         </dependencies>
     </dependencyManagement>