# Batch Iterator

Sequential batch processing with complete fault isolation per record.

**Use when:** Need fault isolation, ordered processing, or simple batch requirements.

## Run

```bash
uv run batch_iterator/worker.py    # Terminal 1
```

```bash
uv run batch_iterator/starter.py   # Terminal 2
```

## How It Works

An `IteratorBatchWorkflow` starts child workflows in parallel for each record. After completion, it calls continue-as-new for the next batch, maintaining bounded history.

**Flow**: `Batch → [Child1|Child2|Child3] → Complete → Continue-as-New`

## Pattern Comparison

| Pattern | Best For | Throughput | Fault Isolation |
|---------|----------|------------|-----------------|
| **Iterator** | Sequential, ordered data | Medium | Complete per record |
| [Sliding Window](../batch_sliding_window/) | High-throughput parallel | High | Complete per record |
| [Heartbeating Activity](../batch_heartbeating_activity/) | Long-running I/O | Medium | Limited (whole batch) |

## Learn More

- [Child Workflows](https://docs.temporal.io/develop/python/child-workflows) - Core pattern functionality
- [Continue-as-New](https://docs.temporal.io/develop/python/continue-as-new) - History management for continuous processing