Best DB for chat

Hello,
- how import is the chat history (if not at all I would just keep it in genserver)
The chat history is important ( Purchases are made by chat )

- how long to you want to save the history
The chat history will be stored for at least 6-12 months.

- how do you work the historical data afterwards (searching, scrolling)
Minimum, just to find some order, or some times open some chat history to check the order.

It will be a chat 1 to 1 ( agent to client or bot to client) and it is expected to have a high number of conversations at the same time