# Replay from Offset

Replay events starting from a specific offset position.

## Usage

```csharp
var replayService = serviceProvider.GetRequiredService<IEventReplayService>();

await foreach (var @event in replayService.ReplayFromOffsetAsync(
    streamName: "orders",
    startOffset: 1000,
    options: new ReplayOptions
    {
        BatchSize = 100,
        MaxEvents = 50000,
        MaxEventsPerSecond = 1000
    }))
{
    await ProcessEventAsync(@event);
}
```

## Options

```csharp
public class ReplayOptions
{
    public int BatchSize { get; set; } = 100;
    public long? MaxEvents { get; set; }  // null = unlimited
    public int? MaxEventsPerSecond { get; set; }  // null = unlimited
    public string[]? EventTypeFilter { get; set; }
    public Action<ReplayProgress>? ProgressCallback { get; set; }
    public TimeSpan ProgressInterval { get; set; } = TimeSpan.FromSeconds(1);
}
```

## Use Cases

### Rebuild Projection from Scratch

```csharp
// Reset checkpoint
await _checkpointStore.DeleteCheckpointAsync("order-summary");

// Replay all events
await foreach (var @event in replayService.ReplayFromOffsetAsync("orders", startOffset: 0))
{
    await _projection.HandleAsync(@event);
    await _checkpointStore.SaveCheckpointAsync("order-summary", @event.Offset);
}
```

### Replay Specific Range

```csharp
// Replay events 1000-2000
long currentOffset = 1000;
const long endOffset = 2000;

await foreach (var @event in replayService.ReplayFromOffsetAsync("orders", startOffset: 1000))
{
    if (@event.Offset > endOffset)
        break;

    await ProcessEventAsync(@event);
}
```

### Resume from Checkpoint

```csharp
// Get last processed offset
var checkpoint = await _checkpointStore.GetCheckpointAsync("analytics");

// Resume from next offset
await foreach (var @event in replayService.ReplayFromOffsetAsync(
    "orders",
    startOffset: checkpoint + 1))
{
    await ProcessAnalyticsAsync(@event);
    await _checkpointStore.SaveCheckpointAsync("analytics", @event.Offset);
}
```

## See Also

- [Event Replay Overview](README.md)
- [Replay from Time](replay-from-time.md)
- [Rate Limiting](rate-limiting.md)
- [Progress Tracking](progress-tracking.md)