BAEL-7319, Introduction to Apache Calcite

persistence-modules/java-calcite/src/test/java/com/baeldung/calcite/CalciteUnitTest.java

@@ -0,0 +1,97 @@
+package com.baeldung.calcite;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.net.URL;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
+
+import org.apache.calcite.adapter.java.ReflectiveSchema;
+import org.apache.calcite.jdbc.CalciteConnection;
+import org.apache.calcite.schema.Schema;
+import org.apache.calcite.schema.SchemaPlus;
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.baledung.calcite.model.CompanySchema;
+import com.baledung.calcite.model.Department;
+import com.baledung.calcite.model.Employee;
+
+public class CalciteUnitTest {
+    Logger logger = LoggerFactory.getLogger(CalciteUnitTest.class);
+    static CompanySchema companySchema = new CompanySchema();
+
+    @Test
+    void whenCsvSchema_thenQuerySuccess() throws SQLException {
+        Properties info = new Properties();
+        info.put("model", getPath("model.json"));
+        try(Connection connection = DriverManager.getConnection("jdbc:calcite:", info)) {
+            Statement statement = connection.createStatement();
+            ResultSet resultSet = statement.executeQuery("select * from trades.trade");
+
+            assertEquals(3, resultSet.getMetaData().getColumnCount());
+
+            List<Integer> tradeIds = new ArrayList<>();
+            while(resultSet.next()) {
+                tradeIds.add(resultSet.getInt("tradeid"));
+            }
+
+            assertEquals(3, tradeIds.size());
+        }
+    }
+
+    private String getPath(String model) {
+        URL url = ClassLoader.getSystemClassLoader().getResource(model);
+        logger.info("path fetched :" + url.getPath());
+        return url.getPath();
+    }
+
+    @BeforeAll
+    static void setup() {
+        Department dept1 = new Department("HR", "Human Resource");
+        Department dept2 = new Department("MKT", "Marketing");
+        Department dept3 = new Department("FIN", "Finance");
+
+        Employee emp1 = new Employee("Tom", "1234", "HR");
+        Employee emp2 = new Employee("Harry", "39731", "FIN");
+        Employee emp3 = new Employee("Danny", "45632", "FIN");
+        Employee emp4 = new Employee("Jenny", "78654", "MKT");
+
+        companySchema.departments = new Department[]{dept1, dept2, dept3};
+        companySchema.employees = new Employee[]{emp1, emp2, emp3, emp4};
+    }
+
+    @Test
+    void whenQueryEmployeesObject_thenQuerySuccess() throws SQLException {
+        Properties info = new Properties();
+        info.setProperty("lex", "JAVA");
+        Connection connection = DriverManager.getConnection("jdbc:calcite:", info);
+        CalciteConnection calciteConnection = connection.unwrap(CalciteConnection.class);
+        SchemaPlus rootSchema = calciteConnection.getRootSchema();
+        Schema schema = new ReflectiveSchema(companySchema);
+        rootSchema.add("company", schema);
+        Statement statement = calciteConnection.createStatement();
+        String query = "select dept.deptName, count(emp.id) "
+            + "from company.employees as emp "
+            + "join company.departments as dept "
+            + "on (emp.deptId = dept.deptId) "
+            + "group by dept.deptName";
+
+        assertDoesNotThrow(() -> {
+            ResultSet resultSet = statement.executeQuery(query);
+            while (resultSet.next()) {
+                logger.info("Dept Name:" + resultSet.getString(1)
+                    + " No. of employees:" + resultSet.getInt(2));
+            }
+        });
+    }
+}

persistence-modules/java-calcite/src/test/resources/model.json

@@ -0,0 +1,14 @@
+{
+  "version": "1.0",
+  "defaultSchema": "TRADES",
+  "schemas": [
+    {
+      "name": "TRADES",
+      "type": "custom",
+      "factory": "org.apache.calcite.adapter.file.FileSchemaFactory",
+      "operand": {
+        "directory": "trades"
+      }
+    }
+  ]
+}

persistence-modules/java-calcite/src/test/resources/trades/TRADE.csv

@@ -0,0 +1,4 @@
+tradeid:int,productid:string,qty:int
+232312123,"RFTXC",100
+232312124,"RFUXC",200
+232312125,"RFSXC",1000