# TiDBChatMessageHistory

> **Class** in `langchain_community`

📖 [View in docs](https://reference.langchain.com/python/langchain-community/chat_message_histories/tidb/TiDBChatMessageHistory)

Represents a chat message history stored in a TiDB database.

## Signature

```python
TiDBChatMessageHistory(
    self,
    session_id: str,
    connection_string: str,
    table_name: str = 'langchain_message_store',
    earliest_time: Optional[datetime] = None,
)
```

## Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `session_id` | `str` | Yes | The ID of the chat session. |
| `connection_string` | `str` | Yes | The connection string for the TiDB database. format: mysql+pymysql://<host>:<PASSWORD>@<host>:4000/<db>?ssl_ca=/etc/ssl/cert.pem&ssl_verify_cert=true&ssl_verify_identity=true |
| `table_name` | `str` | No | the table name to store the chat messages. Defaults to "langchain_message_store". (default: `'langchain_message_store'`) |
| `earliest_time` | `Optional[datetime]` | No | The earliest time to retrieve messages from. Defaults to None. (default: `None`) |

## Extends

- `BaseChatMessageHistory`

## Constructors

```python
__init__(
    self,
    session_id: str,
    connection_string: str,
    table_name: str = 'langchain_message_store',
    earliest_time: Optional[datetime] = None,
)
```

| Name | Type |
|------|------|
| `session_id` | `str` |
| `connection_string` | `str` |
| `table_name` | `str` |
| `earliest_time` | `Optional[datetime]` |


## Properties

- `session_id`
- `table_name`
- `earliest_time`
- `cache`
- `engine`
- `session`
- `messages`

## Methods

- [`add_message()`](https://reference.langchain.com/python/langchain-community/chat_message_histories/tidb/TiDBChatMessageHistory/add_message)
- [`clear()`](https://reference.langchain.com/python/langchain-community/chat_message_histories/tidb/TiDBChatMessageHistory/clear)
- [`reload_cache()`](https://reference.langchain.com/python/langchain-community/chat_message_histories/tidb/TiDBChatMessageHistory/reload_cache)

---

[View source on GitHub](https://github.com/langchain-ai/langchain-community/blob/4b280287bd55b99b44db2dd849f02d66c89534d5/libs/community/langchain_community/chat_message_histories/tidb.py#L15)