Batch Operations with MariaDB Connector/R2DBC (Spring Data)

Overview

Java developers can use MariaDB Connector/R2DBC to connect to MariaDB database products using the Reactive Relational Database Connectivity (R2DBC) API. R2DBC operations are non-blocking, which makes it more scalable than Java's standard JDBC API. MariaDB Connector/R2DBC can be used with the very popular Spring Data R2DBC framework, which can provide support for repositories, object mapping, and transaction management.

Batch Operations

Spring Data R2DBC has no built-in support for batch operations as the native API does with the io.r2dbc.spi.Batch class. With Spring Data R2DBC, batch operations can be performed by looping over a List of SQL statements and invoking DatabaseClient.execute(String sql) for each SQL statement.

Code Example: Batching DML and DDL

DML (Data Manipulation Language) refers to all SQL-data statements in the SQL standard (ISO/IEC 9075-2:2016), for example, DELETE, INSERT, REPLACE, SELECT, and UPDATE.

DDL (Data Definition Language) refers to all SQL-schema statements in the SQL standard (ISO/IEC 9075-2:2016), for example ALTER TABLE, CREATE TABLE, DROP TABLE, CREATE DATABASE, and TRUNCATE TABLE.

The following example shows how to use a batch operation to duplicate the example table created in Setup for Examples:

//Module Imports
import java.util.Arrays;
import java.util.List;
import org.mariadb.r2dbc.MariadbConnectionConfiguration;
import org.mariadb.r2dbc.MariadbConnectionFactory;
import org.springframework.data.r2dbc.core.DatabaseClient;
import reactor.test.StepVerifier;

// Main Application Class
public class App {
   // Connection Configuration
   private static MariadbConnectionConfiguration conf;
   private static MariadbConnectionFactory connFactory;
   private static DatabaseClient client;

   // Main Process
   public static void main(String[] args) {
      try {
         // Configure the Connection
         conf = MariadbConnectionConfiguration.builder()
              .host("192.0.2.1").port(3306)
              .username("db_user").password("db_user_password")
              .database("test").build();

         // Instantiate a Connection Factory
         connFactory = new MariadbConnectionFactory(conf);

         // Instantiate a Database Client
         client = DatabaseClient.create(connFactory);

         // Create a list or batch of SQL statements
         List<String> batch = Arrays.asList(
               "CREATE DATABASE IF NOT EXISTS test;",
               "CREATE TABLE IF NOT EXISTS test.contact_copy(id INT PRIMARY KEY AUTO_INCREMENT,first_name VARCHAR(50),last_name VARCHAR(50),email VARCHAR(250)) ENGINE=InnoDB;",
               "INSERT INTO test.contact_copy SELECT * FROM test.contact;");

         //Run the batch of SQL statements
         batch.forEach(stmt -> client.execute(stmt)
               .fetch()
               .rowsUpdated()
               .as(StepVerifier::create)
               .expectNextCount(1)
               .verifyComplete());

      } catch (IllegalArgumentException e) {
         e.printStackTrace();
      } catch (io.r2dbc.spi.R2dbcNonTransientResourceException e) {
         e.printStackTrace();
      } finally {

      }
   }
}

After running the application App, confirm the table has been created:

USE test;
SHOW TABLES;

+----------------+
| Tables_in_test |
+----------------+
| contact        |
| contact_copy   |
+----------------+

DESCRIBE contact_copy;

+------------+-------------+------+-----+--------------------------+
| Field      | Type        | Null | Key | Default  | Extra         |
+------------+-------------+------+-----+----------+---------------+
| id         | int(11)     | NO   | PRI | NULL     | auto_increment|
| first_Name | varchar(25) | YES  |     | NULL     |               |
| last_Name  | varchar(25) | YES  |     | NULL     |               |
| email      | varchar(25) | YES  |     | NULL     |               |
+------------+-------------+------+-----+----------+---------------+

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