PostgreSQL wire: Java (pgjdbc)

The only change

# host
 postgres.internal
 warehouse.internal
# port
 5432
 5432 (PostgreSQL wire)
# user / password / database
 PostgreSQL values
 MachWarehouse values

JDBC URL: jdbc:postgresql://warehouse.internal:5432/demo?sslmode=verify-full.

Run

mvn -q compile exec:java

Library: org.postgresql:postgresql 42.7.14, Java 25 LTS.

Source

The program as it is kept and tested in the Mach Database Warehouse repository; highlighted lines read the connection setting.

src/main/java/example/Main.java

package example;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

/** Aggregates over the PostgreSQL wire with pgjdbc. Plain JDBC code. */
public final class Main {
    private Main() {}

    public static void main(String[] args) throws Exception {
        // Before: jdbc:postgresql://postgres.internal:5432/demo?sslmode=verify-full
        // After:  jdbc:postgresql://warehouse.internal:5432/demo?sslmode=verify-full
        try (Connection conn = DriverManager.getConnection(
                 System.getenv("JDBC_URL"), System.getenv("DB_USER"), System.getenv("DB_PASSWORD"));
             Statement st = conn.createStatement();
             ResultSet rs = st.executeQuery(
                 "SELECT country, count(*) AS events, sum(revenue) AS revenue FROM events GROUP BY country ORDER BY revenue DESC")) {
            while (rs.next()) {
                System.out.printf("%s\t%d\t%s%n", rs.getString(1), rs.getLong(2), rs.getBigDecimal(3));
            }
        }
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>example.machwarehouse</groupId>
  <artifactId>pgjdbc-example</artifactId>
  <version>1.0.0</version>
  <properties>
    <maven.compiler.release>25</maven.compiler.release>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <exec.mainClass>example.Main</exec.mainClass>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.postgresql</groupId>
      <artifactId>postgresql</artifactId>
      <version>42.7.14</version>
    </dependency>
  </dependencies>
</project>