> For the complete documentation index, see [llms.txt](https://docs.sdv.dev/sdv/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sdv.dev/sdv/~/changes/T3ZD1DOoRUEqkmrAGBZp/sequential-data/data-preparation/sequential-metadata-api.md).

# Sequential Metadata API

This guide will walk you through creating the metadata using the Python API.

## Metadata Creation, Updates & Inspection

{% hint style="success" %}
Use the `SingleTableMetadata` object to create your metadata, modify and inspect it.

**See** [**Single Table API**](/sdv/~/changes/T3ZD1DOoRUEqkmrAGBZp/single-table-data/data-preparation.md) **for more details.**
{% endhint %}

## Sequence Specific Metadata

You can optionally include additional metadata related to your sequences. These methods are available on the `SingleTableMetadata` object.

### set\_sequence\_key

Use this function to set the sequence key of your table. Any existing sequence keys will be removed.

{% hint style="info" %}
The **sequence key** is a column that identify which row(s) belong to which sequences. This is usually an ID column but it may also be a PII sdtype (such as `"phone_number"`).  At this time, SDV does not support composite keys.

This is important for tables that contain multiple sequences. In our example, the sequence key is `'Patient ID'` because this column is used to break up the sequences.

If you don't supply a sequence key, the SDV assumes that your table only contains a single sequence. *Note: The SDV sequential models do not fully support single sequence data.*
{% endhint %}

**Parameters**

* (required) `column_name`: The column name of the sequence key. The column name must already be defined in the metadata and it must be an ID or another PII sdtype.

**Output** (None)

```python
metadata.set_sequence_key(column_name='Patient ID')
```

### set\_sequence\_index

Use this function to set the sequence index of your table. Any existing sequence indices will be removed.

{% hint style="info" %}
The **sequence index** determines the spacing between the rows in a sequence. Use this if you have an explicit index such as a timestamp. If you don't supply a sequence index, the SDV assumes there is equal spacing of an unknown unit.
{% endhint %}

**Parameters**

* (required) `column_name`: The column name of the sequence index. The column name must already be defined in the metadata. It must be either a numerical or datetime column.

**Output** (None)

```python
metadata.set_sequence_index(column_name='Time')
```


---

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