> ## Documentation Index
> Fetch the complete documentation index at: https://langchain.idochub.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Postgres

> [PostgreSQL](https://en.wikipedia.org/wiki/PostgreSQL) also known as `Postgres`, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance.

This notebook goes over how to use Postgres to store chat message history.

```python theme={null}
from langchain_community.chat_message_histories import (
    PostgresChatMessageHistory,
)

history = PostgresChatMessageHistory(
    connection_string="postgresql://postgres:mypassword@localhost/chat_history",
    session_id="foo",
)

history.add_user_message("hi!")

history.add_ai_message("whats up?")
```

```python theme={null}
history.messages
```