# Historian Management

The historian records training data for analysis and visualization.

#### Start Historian

```bash
# Start with default output directory
composabl historian start

# Start with custom output path
composabl historian start /path/to/output/

# Output:
Created the containers.
Service         Container Name  Status   Connection Details      Ports
EMQX           emqx            running  localhost:1883          1883->1883, 18083->18083
Historian      historian       running  /path/to/output/
```

#### Check Historian Status

```bash
# Full status
composabl historian status

# Get EMQX connection string
composabl historian status --moniker-emqx
# Output: localhost:1883

# Get historian output path
composabl historian status --moniker-historian
# Output: /path/to/output/
```

#### Stop Historian

```bash
composabl historian stop
```

#### Clean Up Resources

```bash
# Remove all historian containers and data
composabl historian clean
```

#### Historian Data Format

The historian saves data in Delta Lake format:

```
output_directory/
└── run_id/
    ├── _delta_log/
    │   └── 00000000000000000000.json
    └── part-00000-*.parquet
```

Access data with Python:

```python
from deltalake import DeltaTable

dt = DeltaTable("/path/to/output/run_id")
df = dt.to_pandas()
print(f"Recorded {len(df)} steps")
```


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