HHH-13370: re-enable batching inserts for multi-table entities

hibernate-core/src/main/java/org/hibernate/engine/jdbc/batch/internal/AbstractBatchImpl.java

@@ -133,7 +133,11 @@ public PreparedStatement getBatchStatement(String sql, boolean callable) {
 	}
 
 	private PreparedStatement buildBatchStatement(String sql, boolean callable) {
-		return jdbcCoordinator.getStatementPreparer().prepareStatement( sql, callable );
+		if (statements.isEmpty()) {
+			return jdbcCoordinator.getStatementPreparer().prepareStatement(sql, callable);
+		}
+
+		return jdbcCoordinator.getStatementPreparer().prepareSecondaryBatchStatement(sql, callable);
 	}
 
 	@Override

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

@@ -78,6 +78,12 @@ public PreparedStatement prepareStatement(String sql, final boolean isCallable)
 		return buildPreparedStatementPreparationTemplate( sql, isCallable ).prepareStatement();
 	}
 
+	@Override
+	public PreparedStatement prepareSecondaryBatchStatement(String sql, final boolean isCallable) {
+		//do not execute batch here
+		return buildPreparedStatementPreparationTemplate( sql, isCallable ).prepareStatement();
+	}
+
 	private StatementPreparationTemplate buildPreparedStatementPreparationTemplate(String sql, final boolean isCallable) {
 		return new StatementPreparationTemplate( sql ) {
 			@Override

hibernate-core/src/main/java/org/hibernate/engine/jdbc/spi/StatementPreparer.java

@@ -85,4 +85,14 @@ public interface StatementPreparer {
 	 * @return the prepared statement
 	 */
 	public PreparedStatement prepareQueryStatement(String sql, boolean isCallable, ScrollMode scrollMode);
+
+	/**
+	 * Prepare a second statement for an active batch (e.g. when performing inserts on entities using joined table inheritance).
+	 *
+	 * @param sql The SQL the statement to be prepared
+	 * @param isCallable Whether to prepare as a callable statement.
+	 *
+	 * @return the prepared statement
+	 */
+	public PreparedStatement prepareSecondaryBatchStatement(String sql, boolean isCallable);
 }

hibernate-core/src/test/java/org/hibernate/test/insertordering/InsertOrderingWithJoinedTableInheritance.java

@@ -101,7 +101,7 @@ public void testBatchingAmongstSubClasses() {
 			connectionProvider.clear();
 		} );
 
-		assertEquals( 26, connectionProvider.getPreparedStatements().size() );
+		assertEquals( 4, connectionProvider.getPreparedStatements().size() );
 	}
 
 	@Override

hibernate-core/src/test/java/org/hibernate/test/insertordering/InsertOrderingWithJoinedTableMultiLevelInheritance.java

@@ -102,7 +102,7 @@ public void testBatchingAmongstSubClasses() {
 			connectionProvider.clear();
 		} );
 
-		assertEquals( 17, connectionProvider.getPreparedStatements().size() );
+		assertEquals( 10, connectionProvider.getPreparedStatements().size() );
 	}
 
 	@Override