For RavenDB Google Group Discussion http://groups.google.com/group/ravendb/browse_thread/thread/b22b0d8368603cce#

UseMaxForDateTimeTypeInReduce.cs

using Raven.Database.Indexing;
using Xunit;
using System.Linq;
using System;

namespace Raven.Tests.Bugs.Indexing
{
    public class UseMaxForDateTimeTypeInReduce : LocalClientTest
    {
        private const string map = @"
from doc in docs
from tag in doc.Tags
select new { Name = tag.Name, CreatedTime = doc.CreatedTime }
";

        private const string reduce = @"
from agg in results
group agg by agg.Name into g
let createdTime = g.Max(x => x.CreatedTime)
select new {Name = g.Key, CreatedTime = createdTime}
";

        [Fact]
        public void CanUseMax()
        {
            using (var store = NewDocumentStore())
            {
                store.DatabaseCommands.PutIndex("test",
                                                new IndexDefinition
                                                {
                                                    Map = map,
                                                    Reduce = reduce,
                                                });

                using (var sesion = store.OpenSession())
                {
                    sesion.Store(new { Topic = "RavenDB is Hot", CreatedTime = DateTime.Now, Tags = new[] { new { Name = "DB" }, new { Name = "NoSQL" } } });

                    sesion.Store(new { Topic = "RavenDB is Fast", CreatedTime = DateTime.Now.AddMinutes(10), Tags = new[] { new { Name = "NoSQL" } } });

                    sesion.SaveChanges();
                }

                using (var sesion = store.OpenSession())
                {
                    sesion.Advanced.LuceneQuery<dynamic>("test").WaitForNonStaleResults().ToArray();
                }

                Assert.Empty(store.DocumentDatabase.Statistics.Errors);
            }
        }
    }
}

UseMaxForLongTypeInReduce.cs

using Raven.Database.Indexing;
using Xunit;
using System.Linq;
using System;

namespace Raven.Tests.Bugs.Indexing
{
    public class UseMaxForLongTypeInReduce : LocalClientTest
    {
        private const string map = @"
from doc in docs
from tag in doc.Tags
select new { Name = tag.Name, CreatedTimeTicks = doc.CreatedTimeTicks }
";

        private const string reduce = @"
from agg in results
group agg by agg.Name into g
let createdTimeTicks = g.Max(x => x.CreatedTimeTicks)
select new {Name = g.Key, CreatedTimeTicks = createdTimeTicks}
";

        [Fact]
        public void CanUseMax()
        {
            using (var store = NewDocumentStore())
            {
                store.DatabaseCommands.PutIndex("test",
                                                new IndexDefinition
                                                {
                                                    Map = map,
                                                    Reduce = reduce,
                                                });

                using (var sesion = store.OpenSession())
                {
                    sesion.Store(new { Topic = "RavenDB is Hot", CreatedTimeTicks = DateTime.Now.Ticks, Tags = new[] { new { Name = "DB" }, new { Name = "NoSQL" } } });

                    sesion.Store(new { Topic = "RavenDB is Fast", CreatedTimeTicks = DateTime.Now.AddMinutes(10).Ticks, Tags = new[] { new { Name = "NoSQL" } } });

                    sesion.SaveChanges();
                }

                using (var sesion = store.OpenSession())
                {
                    sesion.Advanced.LuceneQuery<dynamic>("test").WaitForNonStaleResults().ToArray();
                }

                Assert.Empty(store.DocumentDatabase.Statistics.Errors);
            }
        }
    }
}