100 million
live records.

// Query tires directly. No vehicle is loaded.
var tire = db.Query<Tire>()
    .Where(x => x.Color == TireColor.Green)
    .OrderByDescending(x => x.Pressure)
    .First();

// Locate the containing vehicle only when needed.
Vehicle vehicle = db.Root<Vehicle>(tire);

// Change and save the tire itself.
tire.Pressure = 34;
db.Save(tire);

// The vehicle was not required for the save.

var machines = db.Set<MachineState>();

using var hotZone = machines.Subscribe(
    x => x.RegionId == "reactor-7" &&
         x.Enabled &&
         x.Temperature >= 95,
    change =>
    {
        if (change.After is not null)
            cooling.Schedule(change.After.Id);
        else
            cooling.Cancel(change.Before.Id);
    });

var training = db.Query<LearningCase>()
    .Include<Observation>(items => items
        .Where(x => x.Value < x.Minimum || x.Value > x.Maximum)
        .WhereNotExists<AcceptedAnswer>(
            (x, answer) => x.Id == answer.ObservationId,
            answer => answer.Accepted)
        .Select(x => new LearningCase
        {
            ObservationId = x.Id,
            Prompt = x.Description
        }))
    .ToList();

using (var db = MemoryStore.Open(stream, leaveOpen: true))
{
    // 100 million live records
    db.Save();

    if (!db.Verify().IsValid)
        throw new InvalidDataException();
}

stream.Position = 0;
using var reopened = MemoryStore.Open(stream, leaveOpen: true);

var result = db.Apply(
    new MemoryChangeSet()
        .Upsert(
            source: "warehouse-east",
            sequence: 42,
            model: shipment,
            expectedMutationVersion: knownVersion));

switch (result.Status)
{
    case ApplyStatus.Applied:
        PublishCurrentState();
        break;

    case ApplyStatus.AlreadyApplied:
        // Safe retry. Nothing is written twice.
        break;

    case ApplyStatus.Gap:
        RequestMissingChanges();
        break;

    case ApplyStatus.Conflict:
        ResolveConcurrentChange();
        break;
}