db4o Developer Community

Thank you Carl,

> If you want to measure the difference between indexed
> queries and non-indexed queries in one app, you should
> test storing and retrieving objects of different classes.

I cut the example to only one searching method - fullIndex:

import java.io.File;

import com.db4o.Db4o;
import com.db4o.ObjectContainer;


import com.db4o.query.Query;

class Car {  
  private String model;
  private Pilot pilot;
 
  public Car(String model) {
      this.model=model;
      this.pilot=null;
  }
   
  public Pilot getPilot() {
      return pilot;
  }
 
  public void setPilot(Pilot pilot) {
      this.pilot = pilot;
  }
 
  public String getModel() {
      return model;
  }
 
  public String toString() {
      return model+"["+pilot+"]";
  }
}

class Pilot {
  private String name;
  private int points;
 
  public Pilot(final String name, final int points) {
      this.name = name;
      this.points = points;
  }

  public int getPoints() {
      return points;
  }
 
  public void addPoints(int points) {
      this.points+=points;
  }
 
  public String getName() {
      return name;
  }
 
  public String toString() {
      return name+"/"+points;
  }
}


public class FullIndexedExample{

  private static final int COUNTQUERIES = 20;
  private static ObjectContainer db;
 
  public static void main(String[] args) {
    fillUpDB();
    fullIndex();
  }
 
  public static void fillUpDB(){
    new File("formule1.yap").delete();
    db = Db4o.openFile("formule1.yap");
    int count = 1000;
   
    try {
      for (int i=0; i<count;i++){
      addCar(i);
      }
      db.commit();
    }
    finally {
      db.close();
    }
  }
 
  public static void fullIndex() {
    Db4o.configure().objectClass(Car.class).objectField("pilot").indexed(true);
    Db4o.configure().objectClass(Pilot.class).objectField("points").indexed(true);
    db=Db4o.openFile("formule1.yap");
   
    try {
      long avgTime = avgTime();
      System.out.println("Test: index on pilot and points");
      System.out.println("Execution time=" + avgTime + " ms");
    }
    finally {
        db.close();
    }
  }
 
  private static void addCar(final int points){
    Car car = new Car("BMW");
    car.setPilot(new Pilot("pilot" + points, points));
    db.set(car);
  }
   
    private static long avgTime(){
     
      Query query = db.query();
      query.constrain(Car.class);
      query.descend("pilot").descend("points").constrain(99);
     
      long sumType = 0;
      for(int i = 0; i<COUNTQUERIES; i++){
       
        long t1 = System.currentTimeMillis();
        query.execute();
        long t2 = System.currentTimeMillis();
        long  diff = t2 - t1;
         sumType += diff;
       
      }
     
      return sumType/COUNTQUERIES;
    }
   
}

I watched in Object Manager into formule1.yap and both fields were indexed. But result  is average searching time 37 ms among 1000 objects. When I tried to change field pilot from Pilot class to String,  searching time was 0ms. So I see problem in my example is in indexing associated class Pilot.