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*   Cassandra KV

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Cassandra KV
============

This example demonstrates how to setup chat history storage using the `CassandraKVStore` `BaseStore` integration. Note there is a `CassandraChatMessageHistory` integration which may be easier to use for chat history storage; the `CassandraKVStore` is useful if you want a more general-purpose key-value store with prefixable keys.

Setup[​](#setup "Direct link to Setup")
---------------------------------------

*   npm
*   Yarn
*   pnpm

    npm install cassandra-driver

    yarn add cassandra-driver

    pnpm add cassandra-driver

Depending on your database providers, the specifics of how to connect to the database will vary. We will create a document `configConnection` which will be used as part of the store configuration.

### Apache Cassandra®[​](#apache-cassandra "Direct link to Apache Cassandra®")

Storage Attached Indexes (used by `yieldKeys`) are supported in [Apache Cassandra® 5.0](https://cassandra.apache.org/_/blog/Apache-Cassandra-5.0-Features-Storage-Attached-Indexes.html) and above. You can use a standard connection document, for example:

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

### Astra DB[​](#astra-db "Direct link to Astra DB")

Astra DB is a cloud-native Cassandra-as-a-Service platform.

1.  Create an [Astra DB account](https://astra.datastax.com/register).
2.  Create a [vector enabled database](https://astra.datastax.com/createDatabase).
3.  Create a [token](https://docs.datastax.com/en/astra/docs/manage-application-tokens.html) for your database.

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

Instead of `endpoint:`, you many provide property `datacenterID:` and optionally `regionName:`.

Usage[​](#usage "Direct link to Usage")
---------------------------------------

    import { CassandraKVStore } from "@langchain/community/storage/cassandra";import { AIMessage, HumanMessage } from "@langchain/core/messages";// This document is the Cassandra driver connection document; the example is to AstraDB but// any valid Cassandra connection can be used.const configConnection = {  serviceProviderArgs: {    astra: {      token: "YOUR_TOKEN_OR_LOAD_FROM_ENV" as string,      endpoint: "YOUR_ENDPOINT_OR_LOAD_FROM_ENV" as string,    },  },};const store = new CassandraKVStore({  ...configConnection,  keyspace: "test", // keyspace must exist  table: "test_kv", // table will be created if it does not exist  keyDelimiter: ":", // optional, default is "/"});// Define our encoder/decoder for converting between strings and Uint8Arraysconst encoder = new TextEncoder();const decoder = new TextDecoder();/** * Here you would define your LLM and chat chain, call * the LLM and eventually get a list of messages. * For this example, we'll assume we already have a list. */const messages = Array.from({ length: 5 }).map((_, index) => {  if (index % 2 === 0) {    return new AIMessage("ai stuff...");  }  return new HumanMessage("human stuff...");});// Set your messages in the store// The key will be prefixed with `message:id:` and end// with the index.await store.mset(  messages.map((message, index) => [    `message:id:${index}`,    encoder.encode(JSON.stringify(message)),  ]));// Now you can get your messages from the storeconst retrievedMessages = await store.mget(["message:id:0", "message:id:1"]);// Make sure to decode the valuesconsole.log(retrievedMessages.map((v) => decoder.decode(v)));/**[  '{"id":["langchain","AIMessage"],"kwargs":{"content":"ai stuff..."}}',  '{"id":["langchain","HumanMessage"],"kwargs":{"content":"human stuff..."}}'] */// Or, if you want to get back all the keys you can call// the `yieldKeys` method.// Optionally, you can pass a key prefix to only get back// keys which match that prefix.const yieldedKeys = [];for await (const key of store.yieldKeys("message:id:")) {  yieldedKeys.push(key);}// The keys are not encoded, so no decoding is necessaryconsole.log(yieldedKeys);/**[  'message:id:2',  'message:id:1',  'message:id:3',  'message:id:0',  'message:id:4'] */// Finally, let's delete the keys from the storeawait store.mdelete(yieldedKeys);

#### API Reference:

*   [CassandraKVStore](https://v02.api.js.langchain.com/classes/langchain_community_storage_cassandra.CassandraKVStore.html) from `@langchain/community/storage/cassandra`
*   [AIMessage](https://v02.api.js.langchain.com/classes/langchain_core_messages.AIMessage.html) from `@langchain/core/messages`
*   [HumanMessage](https://v02.api.js.langchain.com/classes/langchain_core_messages.HumanMessage.html) from `@langchain/core/messages`

* * *

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*   [Setup](#setup)
    *   [Apache Cassandra®](#apache-cassandra)
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