Fix up Dialect auto-detection

- make it work for DriverManagerConnectionProviderImpl
- improve logging and some confusing exceptions
- make it respect explicit database setting properties

hibernate-core/src/main/java/org/hibernate/boot/registry/selector/spi/StrategyCreator.java

@@ -9,6 +9,7 @@
 /**
  * @author Steve Ebersole
  */
+@FunctionalInterface
 public interface StrategyCreator<T> {
 	T create(Class<? extends T> strategyClass);
 }

hibernate-core/src/main/java/org/hibernate/engine/jdbc/connections/internal/DriverManagerConnectionProviderImpl.java

@@ -8,7 +8,9 @@
 
 import java.sql.Connection;
 import java.sql.Driver;
+import java.sql.DriverManager;
 import java.sql.SQLException;
+import java.util.Enumeration;
 import java.util.Map;
 import java.util.Properties;
 import java.util.concurrent.ConcurrentLinkedQueue;
@@ -22,6 +24,7 @@
 import org.hibernate.HibernateException;
 import org.hibernate.boot.registry.classloading.spi.ClassLoaderService;
 import org.hibernate.cfg.AvailableSettings;
+import org.hibernate.dialect.Database;
 import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
 import org.hibernate.internal.CoreLogging;
 import org.hibernate.internal.CoreMessageLogger;
@@ -101,10 +104,51 @@ private PooledConnections buildPool(Map configurationValues, ServiceRegistryImpl
 	private static ConnectionCreator buildCreator(Map configurationValues, ServiceRegistryImplementor serviceRegistry) {
 		final ConnectionCreatorBuilder connectionCreatorBuilder = new ConnectionCreatorBuilder( serviceRegistry );
 
-		final String driverClassName = (String) configurationValues.get( AvailableSettings.DRIVER );
-		connectionCreatorBuilder.setDriver( loadDriverIfPossible( driverClassName, serviceRegistry ) );
-
 		final String url = (String) configurationValues.get( AvailableSettings.URL );
+
+		String driverClassName = (String) configurationValues.get( AvailableSettings.DRIVER );
+		boolean success = false;
+		if ( driverClassName != null ) {
+			connectionCreatorBuilder.setDriver( loadDriverIfPossible( driverClassName, serviceRegistry ) );
+			success = true;
+		}
+		else if ( url != null ) {
+			//try to guess the driver class from the JDBC URL
+			for ( Database database: Database.values() ) {
+				if ( database.matchesUrl( url ) ) {
+					driverClassName = database.getDriverClassName( url );
+					if ( driverClassName != null ) {
+						try {
+							connectionCreatorBuilder.setDriver( loadDriverIfPossible(driverClassName, serviceRegistry) );
+							success = true;
+						}
+						catch (Exception e) {
+							//swallow it, since this was not
+							//an explicit setting by the user
+						}
+						break;
+					}
+				}
+			}
+		}
+
+		if ( success ) {
+			log.loadedDriver( driverClassName );
+		}
+		else {
+			//we're hoping that the driver is already loaded
+			log.noDriver( AvailableSettings.DRIVER );
+			StringBuilder list = new StringBuilder();
+			Enumeration<Driver> drivers = DriverManager.getDrivers();
+			while ( drivers.hasMoreElements() ) {
+				if ( list.length() != 0) {
+					list.append(", ");
+				}
+				list.append( drivers.nextElement().getClass().getName() );
+			}
+			log.loadedDrivers( list.toString() );
+		}
+
 		if ( url == null ) {
 			final String msg = log.jdbcUrlNotSpecified( AvailableSettings.URL );
 			log.error( msg );
@@ -112,7 +156,7 @@ private static ConnectionCreator buildCreator(Map configurationValues, ServiceRe
 		}
 		connectionCreatorBuilder.setUrl( url );
 
-		log.usingDriver( driverClassName, url );
+		log.usingUrl( url );
 
 		final Properties connectionProps = ConnectionProviderInitiator.getConnectionProperties( configurationValues );
 
@@ -217,7 +261,6 @@ protected void finalize() throws Throwable {
 
 	/**
 	 * Exposed to facilitate testing only.
-	 * @return
 	 */
 	public Properties getConnectionProperties() {
 		BasicConnectionCreator connectionCreator = (BasicConnectionCreator) this.state.pool.connectionCreator;

hibernate-core/src/main/java/org/hibernate/engine/jdbc/dialect/internal/DialectFactoryImpl.java

@@ -6,10 +6,12 @@
  */
 package org.hibernate.engine.jdbc.dialect.internal;
 
+import java.lang.reflect.InvocationTargetException;
 import java.util.Map;
 
 import org.hibernate.HibernateException;
 import org.hibernate.annotations.common.util.StringHelper;
+import org.hibernate.boot.registry.selector.spi.StrategySelectionException;
 import org.hibernate.boot.registry.selector.spi.StrategySelector;
 import org.hibernate.cfg.AvailableSettings;
 import org.hibernate.dialect.Dialect;
@@ -48,7 +50,7 @@ public void setDialectResolver(DialectResolver dialectResolver) {
 	public Dialect buildDialect(Map configValues, DialectResolutionInfoSource resolutionInfoSource) throws HibernateException {
 		final Object dialectReference = configValues.get( AvailableSettings.DIALECT );
 		if ( !isEmpty( dialectReference ) ) {
-			return constructDialect( dialectReference );
+			return constructDialect( dialectReference, resolutionInfoSource );
 		}
 		else {
 			return determineDialect( resolutionInfoSource );
@@ -68,10 +70,32 @@ private boolean isEmpty(Object dialectReference) {
 		return true;
 	}
 
-	private Dialect constructDialect(Object dialectReference) {
-		final Dialect dialect;
+	private Dialect constructDialect(Object dialectReference, DialectResolutionInfoSource resolutionInfoSource) {
 		try {
-			dialect = strategySelector.resolveStrategy( Dialect.class, dialectReference );
+			Dialect dialect = strategySelector.resolveStrategy(
+					Dialect.class,
+					dialectReference,
+					(Dialect) null,
+					(dialectClass) -> {
+						try {
+							try {
+								if (resolutionInfoSource != null) {
+									return dialectClass.getConstructor(DialectResolutionInfo.class).newInstance(
+											resolutionInfoSource.getDialectResolutionInfo()
+									);
+								}
+							}
+							catch (NoSuchMethodException nsme) {}
+							return dialectClass.newInstance();
+						}
+						catch (InstantiationException | IllegalAccessException | InvocationTargetException e) {
+							throw new StrategySelectionException(
+									String.format( "Could not instantiate named dialect class [%s]", dialectClass.getName() ),
+									e
+							);
+						}
+					}
+			);
 			if ( dialect == null ) {
 				throw new HibernateException( "Unable to construct requested dialect [" + dialectReference + "]" );
 			}
@@ -100,7 +124,6 @@ private Dialect determineDialect(DialectResolutionInfoSource resolutionInfoSourc
 			throw new HibernateException(
 					"Unable to determine Dialect without JDBC metadata "
 					+ "(please set 'javax.persistence.jdbc.url', 'hibernate.connection.url', or 'hibernate.dialect')"
-
 			);
 		}
 
@@ -109,9 +132,9 @@ private Dialect determineDialect(DialectResolutionInfoSource resolutionInfoSourc
 
 		if ( dialect == null ) {
 			throw new HibernateException(
-					"Unable to determine Dialect to use [name=" + info.getDatabaseName() +
-							", majorVersion=" + info.getDatabaseMajorVersion() +
-							"]; user must register resolver or explicitly set 'hibernate.dialect'"
+					"Unable to determine Dialect for " + info.getDatabaseName() + " "
+					+ info.getDatabaseMajorVersion() + "." + info.getDatabaseMinorVersion()
+					+ " (please set 'hibernate.dialect' or register a Dialect resolver)"
 			);
 		}
 

hibernate-core/src/main/java/org/hibernate/engine/jdbc/env/internal/ExtractedDatabaseMetaDataImpl.java

@@ -9,7 +9,6 @@
 import java.sql.DatabaseMetaData;
 import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
@@ -22,7 +21,6 @@
 import org.hibernate.engine.jdbc.env.spi.JdbcEnvironment;
 import org.hibernate.engine.jdbc.env.spi.SQLStateType;
 import org.hibernate.engine.jdbc.spi.TypeInfo;
-import org.hibernate.internal.util.StringHelper;
 import org.hibernate.tool.schema.extract.spi.SequenceInformation;
 
 /**
@@ -201,8 +199,13 @@ public Builder apply(DatabaseMetaData databaseMetaData) throws SQLException {
 			doesDataDefinitionCauseTransactionCommit = databaseMetaData.dataDefinitionCausesTransactionCommit();
 			extraKeywords = parseKeywords( databaseMetaData.getSQLKeywords() );
 			sqlStateType = SQLStateType.interpretReportedSQLStateType( databaseMetaData.getSQLStateType() );
-			lobLocatorUpdateCopy = databaseMetaData.locatorsUpdateCopy();
-			typeInfoSet = new LinkedHashSet<TypeInfo>();
+			try {
+				lobLocatorUpdateCopy = databaseMetaData.locatorsUpdateCopy();
+			}
+			catch (SQLException sql) {
+				//ignore, the database might not support this at all
+			}
+			typeInfoSet = new LinkedHashSet<>();
 			typeInfoSet.addAll( TypeInfo.extractTypeInfo( databaseMetaData ) );
 			return this;
 		}

hibernate-core/src/main/java/org/hibernate/engine/jdbc/env/internal/JdbcEnvironmentInitiator.java

@@ -14,6 +14,7 @@
 import org.hibernate.HibernateException;
 import org.hibernate.MultiTenancyStrategy;
 import org.hibernate.boot.registry.StandardServiceInitiator;
+import org.hibernate.cfg.AvailableSettings;
 import org.hibernate.dialect.Dialect;
 import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
 import org.hibernate.engine.jdbc.connections.spi.JdbcConnectionAccess;
@@ -62,7 +63,48 @@ public JdbcEnvironment initiateService(Map configurationValues, ServiceRegistryI
 				true
 		);
 
-		if ( useJdbcMetadata ) {
+		if ( configurationValues.containsKey( AvailableSettings.HBM2DDL_DB_NAME ) ) {
+			return new JdbcEnvironmentImpl( registry, dialectFactory.buildDialect(
+					configurationValues,
+					() -> new DialectResolutionInfo() {
+						@Override
+						public String getDatabaseName() {
+							return (String) configurationValues.get( AvailableSettings.HBM2DDL_DB_NAME );
+						}
+
+						@Override
+						public String getDatabaseVersion() {
+							return (String) configurationValues.getOrDefault( AvailableSettings.HBM2DDL_DB_VERSION, "0" );
+						}
+
+						@Override
+						public int getDatabaseMajorVersion() {
+							return (Integer) configurationValues.getOrDefault( AvailableSettings.HBM2DDL_DB_MAJOR_VERSION, 0 );
+						}
+
+						@Override
+						public int getDatabaseMinorVersion() {
+							return (Integer) configurationValues.getOrDefault( AvailableSettings.HBM2DDL_DB_MINOR_VERSION, 0 );
+						}
+
+						@Override
+						public String getDriverName() {
+							throw new UnsupportedOperationException();
+						}
+
+						@Override
+						public int getDriverMajorVersion() {
+							throw new UnsupportedOperationException();
+						}
+
+						@Override
+						public int getDriverMinorVersion() {
+							throw new UnsupportedOperationException();
+						}
+					}
+			) );
+		}
+		else if ( useJdbcMetadata ) {
 			final JdbcConnectionAccess jdbcConnectionAccess = buildJdbcConnectionAccess( configurationValues, registry );
 			try {
 				final Connection connection = jdbcConnectionAccess.obtainConnection();
@@ -96,26 +138,19 @@ public JdbcEnvironment initiateService(Map configurationValues, ServiceRegistryI
 
 					Dialect dialect = dialectFactory.buildDialect(
 							configurationValues,
-							new DialectResolutionInfoSource() {
-								@Override
-								public DialectResolutionInfo getDialectResolutionInfo() {
-									try {
-										return new DatabaseMetaDataDialectResolutionInfoAdapter( connection.getMetaData() );
-									}
-									catch ( SQLException sqlException ) {
-										throw new HibernateException(
-												"Unable to access java.sql.DatabaseMetaData to determine appropriate Dialect to use",
-												sqlException
-										);
-									}
+							() -> {
+								try {
+									return new DatabaseMetaDataDialectResolutionInfoAdapter( connection.getMetaData() );
+								}
+								catch ( SQLException sqlException ) {
+									throw new HibernateException(
+											"Unable to access java.sql.DatabaseMetaData to determine appropriate Dialect to use",
+											sqlException
+									);
 								}
 							}
 					);
-					return new JdbcEnvironmentImpl(
-							registry,
-							dialect,
-							dbmd
-					);
+					return new JdbcEnvironmentImpl( registry, dialect, dbmd );
 				}
 				catch (SQLException e) {
 					log.unableToObtainConnectionMetadata( e.getMessage() );

hibernate-core/src/main/java/org/hibernate/internal/log/ConnectionPoolingLogger.java

@@ -9,8 +9,6 @@
 import java.sql.SQLException;
 import java.util.Properties;
 
-import org.hibernate.engine.jdbc.connections.spi.JdbcConnectionAccess;
-
 import org.jboss.logging.BasicLogger;
 import org.jboss.logging.Logger;
 import org.jboss.logging.annotations.Cause;
@@ -48,12 +46,24 @@ public interface ConnectionPoolingLogger extends BasicLogger {
 	@Message(value = "Autocommit mode: %s", id = 10001003)
 	void autoCommitMode(boolean autocommit);
 
-	@Message(value = "JDBC URL was not specified by property %s", id = 10001004)
-	String jdbcUrlNotSpecified(String url);
+	@Message(value = "No JDBC URL specified by property %s", id = 10001004)
+	String jdbcUrlNotSpecified(String property);
 
 	@LogMessage(level = INFO)
-	@Message(value = "using driver [%s] at URL [%s]", id = 10001005)
-	void usingDriver(String driverClassName, String url);
+	@Message(value = "Loaded JDBC driver class: %s", id = 10001005)
+	void loadedDriver(String driverClassName);
+
+	@LogMessage(level = INFO)
+	@Message(value = "No JDBC driver class specified by %s", id = 10001010)
+	void noDriver(String property);
+
+	@LogMessage(level = INFO)
+	@Message(value = "Loaded JDBC drivers: %s", id = 10001011)
+	void loadedDrivers(String loadedDrivers);
+
+	@LogMessage(level = INFO)
+	@Message(value = "Connecting with JDBC URL [%s]", id = 10001012)
+	void usingUrl(String url);
 
 	@LogMessage(level = WARN)
 	@Message(value = "No JDBC Driver class was specified by property %s", id = 10001006)