I spent an hour testing db4o and ravenDb as well just to see how these scale in a dataintensive scenario, as such scenarios are most interesting to me. The result is that both object oriented databases do not perform well with dataseries. The test scenario is an oversimplified object graph containing a single class and a series of data in a list. More specific a simble class Valuta containing historical hourly valuta values for the last 27,5 years. In comparison I've worked with a big object graph containing data series around 800 000 values (records) and saving/fetching this massive amount of data from a relational database using NHibernate took around 2 seconds (of course I had spent some time optimizing NHibernate and the DB to achieve that result).
And here are the results,
Performance test of db4o saving and loading 240 000 valuta value instances in milliseconds:
Saving operation:
Time used inserting data: 15478
Press 'Enter' to continue....
Loading operation:
Time used executing query: 10802
Press 'Enter' to continue....
And the code:
Code:
using System;
using System.Collections.Generic;
using System.Linq;
using Db4objects.Db4o;
namespace Db4Objects
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Press 'Enter' to read from database");
ConsoleKeyInfo keyPressed = Console.ReadKey();
var store = Db4oEmbedded.OpenFile("db4oTest.Yap");
if (keyPressed.Key == ConsoleKey.Enter) ReadFromDB(store);
else InsertIntoDB(store);
store.Dispose();
}
private static void ReadFromDB(IObjectContainer store)
{
TimeSpan timeUsed;
DateTime start = DateTime.Now;
var v = store.Query<Valuta>().SingleOrDefault(x => x.Name == "GBP");//Where(x => x.Name.Equals("GBP"))
//Advanced.LuceneQuery<Valuta>("ValutaIndex").Where("Name:GBP").WaitForNonStaleResults().Single();
timeUsed = DateTime.Now - start;
Console.WriteLine("Valuta: {0} | {1}", v.Id, v.Name);
foreach (var val in v.Values)
{
Console.WriteLine("Val: {0} at {1}", val.Value, val.Time);
}
Console.WriteLine("Time used executing query: "+timeUsed.TotalMilliseconds);
Console.WriteLine("Press 'Enter' to continue....");
Console.ReadLine();
}
private static void InsertIntoDB(IObjectContainer store)
{
DateTime today = DateTime.Now.Date;
int numberOfValues = 240000;
ValutaValue[] values = new ValutaValue[numberOfValues];
for (int i = 0; i < numberOfValues; i++)
{
values[i] = new ValutaValue { Time = today.AddHours(-i), Value = 8 * (i / 10) };
}
var valuta = new Valuta()
{
Name = "GBP",
Values = new List<ValutaValue>(values)
};
TimeSpan timeUsed;
DateTime start = DateTime.Now;
store.Store(valuta);
store.Commit();
timeUsed = DateTime.Now - start;
Console.WriteLine("Time used inserting data: " + timeUsed.TotalMilliseconds);
Console.WriteLine("Press 'Enter' to continue....");
Console.ReadLine();
}
}
public class Valuta
{
public string Id { get; set; }
public string Name { get; set; }
public IList<ValutaValue> Values { get; set; }
}
public struct ValutaValue
{
public DateTime Time { get; set; }
public double Value { get; set; }
}
}
Performance test of RavenDB saving and loading 240 000 valuta values instances in milliseconds:
Saving operation:
Time used inserting data: 12027,6
Press 'Enter' to continue....
Loading operation:
Time used executing query: 14138,6
Press 'Enter' to continue....
Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Raven.Client.Document;
using Raven.Client.Indexes;
namespace ConsoleAppRavenTest
{
class Program
{
static void Main(string[] args)
{
var store = new DocumentStore { Url = "http://localhost:8080" };
store.Initialize();
Console.WriteLine("Press 'Enter' to read from database");
ConsoleKeyInfo keyPressed = Console.ReadKey();
if (keyPressed.Key == ConsoleKey.Enter) ReadFromDB(store);
else InsertIntoDB(store);
}
private static void ReadFromDB(DocumentStore store)
{
/*store.DatabaseCommands.PutIndex("ValutaIndex", new IndexDefinitionBuilder<Valuta>
{
Map = valutas => from valuta in valutas from v in valuta.Values select new { v.Time }
});*/
TimeSpan timeUsed;
using (var session = store.OpenSession())
{
//var all = session.Query<Valuta>().ToArray();
DateTime start = DateTime.Now;
var v = session.Query<Valuta>().SingleOrDefault(x => x.Name == "GBP");//Where(x => x.Name.Equals("GBP"))
//Advanced.LuceneQuery<Valuta>("ValutaIndex").Where("Name:GBP").WaitForNonStaleResults().Single();
timeUsed = DateTime.Now - start;
Console.WriteLine("Valuta: {0} | {1}", v.Id, v.Name);
foreach (var val in v.Values)
{
Console.WriteLine("Val: {0} at {1}", val.Value, val.Time);
}
}
Console.WriteLine("Time used executing query: "+timeUsed.TotalMilliseconds);
Console.WriteLine("Press 'Enter' to continue....");
Console.ReadLine();
}
private static void InsertIntoDB(DocumentStore store)
{
DateTime today = DateTime.Now.Date;
int numberOfValues = 240000;
ValutaValue[] values = new ValutaValue[numberOfValues];
for (int i = 0; i < numberOfValues; i++)
{
values[i] = new ValutaValue { Time = today.AddHours(-i), Value = 8 * (i / 10) };
}
using (var session = store.OpenSession())
{
var valuta = new Valuta()
{
Name = "GBP",
Values = new List<ValutaValue>(values)
};
TimeSpan timeUsed;
DateTime start = DateTime.Now;
session.Store(valuta);
session.SaveChanges();
timeUsed = DateTime.Now - start;
Console.WriteLine("Time used inserting data: " + timeUsed.TotalMilliseconds);
Console.WriteLine("Press 'Enter' to continue....");
Console.ReadLine();
}
}
}
public class Valuta
{
public string Id { get; set; }
public string Name { get; set; }
public IList<ValutaValue> Values { get; set; }
}
public struct ValutaValue
{
public DateTime Time { get; set; }
public double Value { get; set; }
}
}
I'm not saying these databases are useless, I'm just saying that they are probably not meant for wast dataseries. As always, choose the appropriate tool for the job... ;-)
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