Cassandra 聊天记忆

为了在聊天会话中实现更长期的持久性，您可以将支持 BufferMemory 等聊天记忆类别的默认内存中 chatHistory 替换为 Cassandra 集群。

设置

首先，安装 Cassandra Node.js 驱动程序

提示

请参阅此部分，了解有关安装集成包的通用说明。

npm

npm install cassandra-driver @langchain/openai @langchain/community @langchain/core

Yarn

yarn add cassandra-driver @langchain/openai @langchain/community @langchain/core

pnpm

pnpm add cassandra-driver @langchain/openai @langchain/community @langchain/core

根据您的数据库提供商，连接到数据库的具体方法会有所不同。我们将创建一个 configConnection 文档，它将用作向量存储配置的一部分。

Apache Cassandra®

const configConnection = {
  contactPoints: ['h1', 'h2'],
  localDataCenter: 'datacenter1',
  credentials: {
    username: <...> as string,
    password: <...> as string,
  },
};

Astra DB

Astra DB 是一个云原生的 Cassandra 即服务平台。

1. 创建一个 Astra DB 账户。
2. 创建一个 启用向量的数据库。
3. 为您的数据库创建一个 令牌。

const configConnection = {
  serviceProviderArgs: {
    astra: {
      token: <...> as string,
      endpoint: <...> as string,
    },
  },
};

除了 endpoint: 之外，您还可以提供属性 datacenterID: 和可选的 regionName:。

用法

import { BufferMemory } from "langchain/memory";
import { CassandraChatMessageHistory } from "@langchain/community/stores/message/cassandra";
import { ChatOpenAI } from "@langchain/openai";
import { ConversationChain } from "langchain/chains";

// The example below uses Astra DB, but you can use any Cassandra connection
const configConnection = {
  serviceProviderArgs: {
    astra: {
      token: "<your Astra Token>" as string,
      endpoint: "<your Astra Endpoint>" as string,
    },
  },
};

const memory = new BufferMemory({
  chatHistory: new CassandraChatMessageHistory({
    ...configConnection,
    keyspace: "langchain",
    table: "message_history",
    sessionId: "<some unique session identifier>",
  }),
});

const model = new ChatOpenAI();
const chain = new ConversationChain({ llm: model, memory });

const res1 = await chain.invoke({ input: "Hi! I'm Jonathan." });
console.log({ res1 });
/*
{
  res1: {
    text: "Hello Jonathan! How can I assist you today?"
  }
}
*/

const res2 = await chain.invoke({ input: "What did I just say my name was?" });
console.log({ res2 });

/*
{
  res1: {
    text: "You said your name was Jonathan."
  }
}
*/

API 参考

• BufferMemory 来自 langchain/memory
• CassandraChatMessageHistory 来自 @langchain/community/stores/message/cassandra
• ChatOpenAI 来自 @langchain/openai
• ConversationChain 来自 langchain/chains