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hide_table_of_contents: true
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import CodeBlock from "@theme/CodeBlock";

# Redis-Backed Chat Memory

For longer-term persistence across chat sessions, you can swap out the default in-memory `chatHistory` that backs chat memory classes like `BufferMemory` for a [Redis](https://redis.io/) instance.

## Setup

You will need to install [node-redis](https://github.com/redis/node-redis) in your project:

```bash npm2yarn
npm install redis
```

You will also need a Redis instance to connect to. See instructions on [the official Redis website](https://redis.io/docs/getting-started/) for running the server locally.

## Usage

Each chat history session stored in Redis must have a unique id. You can provide an optional `sessionTTL` to make sessions expire after a give number of seconds.
The `config` parameter is passed directly into the `createClient` method of [node-redis](https://github.com/redis/node-redis), and takes all the same arguments.

import Example from "@examples/memory/redis.ts";

<CodeBlock language="typescript">{Example}</CodeBlock>

## Advanced Usage

You can also directly pass in a previously created [node-redis](https://github.com/redis/node-redis) client instance:

import AdvancedExample from "@examples/memory/redis-advanced.ts";

<CodeBlock language="typescript">{AdvancedExample}</CodeBlock>

### Redis Sentinel Support

You can enable a Redis Sentinel backed cache using [ioredis](https://github.com/redis/ioredis)

This will require the installation of [ioredis](https://github.com/redis/ioredis) in your project.

```bash npm2yarn
npm install ioredis
```

import RedisSentinel from "@examples/memory/redis-sentinel.ts";

<CodeBlock language="typescript">{RedisSentinel}</CodeBlock>