vmuzikar · Nov 2, 2026 · Oct 31, 2026 · Nov 2, 2026
@@ -19,6 +19,7 @@
 
 import org.hibernate.dialect.H2Dialect;
 import org.hibernate.dialect.sql.ast.H2SqlAstTranslator;
+import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.sql.ast.SqlAstTranslator;
 import org.hibernate.sql.ast.SqlAstTranslatorFactory;
@@ -35,6 +36,14 @@
  */
 public class KeycloakH2Dialect extends H2Dialect {
 
+    public KeycloakH2Dialect() {
+        super();
+    }
+
+    public KeycloakH2Dialect(DialectResolutionInfo info) {
+        super(info);
+    }
+
     @Override
     public SqlAstTranslatorFactory getSqlAstTranslatorFactory() {
         return new StandardSqlAstTranslatorFactory() {

@@ -19,6 +19,7 @@
 
 import org.hibernate.dialect.OracleDialect;
 import org.hibernate.dialect.sql.ast.OracleSqlAstTranslator;
+import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.sql.ast.SqlAstTranslator;
 import org.hibernate.sql.ast.SqlAstTranslatorFactory;
@@ -41,6 +42,14 @@
  */
 public class KeycloakOracleDialect extends OracleDialect {
 
+    public KeycloakOracleDialect() {
+        super();
+    }
+
+    public KeycloakOracleDialect(DialectResolutionInfo info) {
+        super(info);
+    }
+
     @Override
     public SqlAstTranslatorFactory getSqlAstTranslatorFactory() {
         return new StandardSqlAstTranslatorFactory() {

@@ -20,6 +20,7 @@
 import org.hibernate.LockMode;
 import org.hibernate.dialect.SQLServerDialect;
 import org.hibernate.dialect.sql.ast.SQLServerSqlAstTranslator;
+import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.sql.ast.SqlAstTranslator;
 import org.hibernate.sql.ast.SqlAstTranslatorFactory;
@@ -40,6 +41,14 @@
  */
 public class KeycloakSQLServerDialect extends SQLServerDialect {
 
+    public KeycloakSQLServerDialect() {
+        super();
+    }
+
+    public KeycloakSQLServerDialect(DialectResolutionInfo info) {
+        super(info);
+    }
+
     @Override
     public SqlAstTranslatorFactory getSqlAstTranslatorFactory() {
         return new StandardSqlAstTranslatorFactory() {

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2026 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.keycloak.connections.jpa.dialect;
+
+import java.util.List;
+
+import org.hibernate.dialect.Dialect;
+import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(Parameterized.class)
+public class KeycloakDialectTest {
+    @Parameterized.Parameters(name = "{0}")
+    public static List<Class<? extends Dialect>> dialects() {
+        return List.of(KeycloakH2Dialect.class, KeycloakOracleDialect.class, KeycloakSQLServerDialect.class);
+    }
+
+    @Parameterized.Parameter
+    public Class<? extends Dialect> dialect;
+
+    @Test
+    public void exposesPublicConstructorsUsedByHibernate() throws Exception {
+        // Constructors are not inherited. Hibernate falls back to no-argument construction
+        // when the dialect does not expose the metadata constructor, losing database capabilities.
+        assertEquals(dialect, dialect.getConstructor(DialectResolutionInfo.class).getDeclaringClass());
+        assertEquals(dialect, dialect.getConstructor().getDeclaringClass());
+    }
+}
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2026 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.keycloak.connections.jpa.dialect;
+
+import java.sql.DriverManager;
+
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.engine.jdbc.env.spi.JdbcEnvironment;
+import org.jboss.logging.Logger;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class KeycloakH2DialectTest {
+    private static final Logger LOG = Logger.getLogger(KeycloakH2DialectTest.class);
+
+    @Test
+    public void hibernatePassesDetectedDatabaseVersionToDialect() throws Exception {
+        String url = "jdbc:h2:mem:dialect-version";
+        var registry = new StandardServiceRegistryBuilder()
+                .applySetting("hibernate.connection.url", url)
+                .applySetting("hibernate.connection.username", "sa")
+                .applySetting("hibernate.connection.password", "")
+                .applySetting("hibernate.dialect", KeycloakH2Dialect.class.getName())
+                .build();
+        try (var connection = DriverManager.getConnection(url, "sa", "")) {
+            var metadata = connection.getMetaData();
+            var dialect = registry.getService(JdbcEnvironment.class).getDialect();
+            var version = dialect.getVersion();
+            LOG.infof("H2 database version: %s; identified dialect version: %s",
+                    metadata.getDatabaseProductVersion(), version);
+            assertEquals(KeycloakH2Dialect.class, dialect.getClass());
+            assertEquals(metadata.getDatabaseMajorVersion(), version.getDatabaseMajorVersion());
+            assertEquals(metadata.getDatabaseMinorVersion(), version.getDatabaseMinorVersion());
+            // H2 includes the patch version followed by its release date in JDBC metadata.
+            String patch = metadata.getDatabaseProductVersion().split("[. ]")[2];
+            assertEquals(Integer.parseInt(patch), version.getDatabaseMicroVersion());
+        } finally {
+            StandardServiceRegistryBuilder.destroy(registry);
+        }
+    }
+}