doc: Add doc for CassandraByteStore (#22126)

Preview:
https://langchain-git-fork-cbornet-doc-cassandrabytestore-langchain.vercel.app/v0.2/docs/integrations/stores/cassandra/

docs/docs/integrations/stores/cassandra.ipynb

@@ -0,0 +1,228 @@
+{
+ "cells": [
+  {
+   "cell_type": "raw",
+   "metadata": {},
+   "source": [
+    "---\n",
+    "sidebar_label: Cassandra\n",
+    "---"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Cassandra\n",
+    "\n",
+    "[Cassandra](https://cassandra.apache.org/) is a NoSQL, row-oriented, highly scalable and highly available database.\n",
+    "\n",
+    "`CassandraByteStore` needs the `cassio` package to be installed:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "vscode": {
+     "languageId": "plaintext"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "%pip install --upgrade --quiet  cassio"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The Store takes the following parameters:\n",
+    "\n",
+    "* table:  The table where to store the data.\n",
+    "* session: (Optional) The cassandra driver session. If not provided, the cassio resolved session will be used.\n",
+    "* keyspace: (Optional) The keyspace of the table. If not provided, the cassio resolved keyspace will be used.\n",
+    "* setup_mode: (Optional) The mode used to create the Cassandra table (SYNC, ASYNC or OFF). Defaults to SYNC."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## CassandraByteStore\n",
+    "\n",
+    "The `CassandraByteStore` is an implementation of `ByteStore` that stores the data in your Cassandra instance.\n",
+    "The store keys must be strings and will be mapped to the `row_id` column of the Cassandra table.\n",
+    "The store `bytes` values are mapped to the `body_blob` column of the Cassandra table."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain_community.storage import CassandraByteStore"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "### Init from a cassandra driver Session\n",
+    "\n",
+    "You need to create a `cassandra.cluster.Session` object, as described in the [Cassandra driver documentation](https://docs.datastax.com/en/developer/python-driver/latest/api/cassandra/cluster/#module-cassandra.cluster). The details vary (e.g. with network settings and authentication), but this might be something like:"
+   ],
+   "metadata": {
+    "collapsed": false
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from cassandra.cluster import Cluster\n",
+    "\n",
+    "cluster = Cluster()\n",
+    "session = cluster.connect()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "You need to provide the name of an existing keyspace of the Cassandra instance:"
+   ],
+   "metadata": {
+    "collapsed": false
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "CASSANDRA_KEYSPACE = input(\"CASSANDRA_KEYSPACE = \")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "Creating the store:"
+   ],
+   "metadata": {
+    "collapsed": false
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "[b'v1', b'v2']\n"
+     ]
+    }
+   ],
+   "source": [
+    "store = CassandraByteStore(\n",
+    "    table=\"my_store\",\n",
+    "    session=session,\n",
+    "    keyspace=CASSANDRA_KEYSPACE,\n",
+    ")\n",
+    "\n",
+    "store.mset([(\"k1\", b\"v1\"), (\"k2\", b\"v2\")])\n",
+    "print(store.mget([\"k1\", \"k2\"]))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "### Init from cassio\n",
+    "\n",
+    "It's also possible to use cassio to configure the session and keyspace."
+   ],
+   "metadata": {
+    "collapsed": false
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "outputs": [],
+   "source": [
+    "import cassio\n",
+    "\n",
+    "cassio.init(contact_points=\"127.0.0.1\", keyspace=CASSANDRA_KEYSPACE)\n",
+    "\n",
+    "store = CassandraByteStore(\n",
+    "    table=\"my_store\",\n",
+    ")\n",
+    "\n",
+    "store.mset([(\"k1\", b\"v1\"), (\"k2\", b\"v2\")])\n",
+    "print(store.mget([\"k1\", \"k2\"]))"
+   ],
+   "metadata": {
+    "collapsed": false
+   }
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "### Usage with CacheBackedEmbeddings\n",
+    "\n",
+    "You may use the `CassandraByteStore` in conjunction with a [`CacheBackedEmbeddings`](/docs/how_to/caching_embeddings) to cache the result of embeddings computations.\n"
+   ],
+   "metadata": {
+    "collapsed": false
+   }
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "outputs": [],
+   "source": [
+    "from langchain.embeddings import CacheBackedEmbeddings\n",
+    "from langchain_openai import OpenAIEmbeddings\n",
+    "\n",
+    "cassio.init(contact_points=\"127.0.0.1\", keyspace=CASSANDRA_KEYSPACE)\n",
+    "\n",
+    "store = CassandraByteStore(\n",
+    "    table=\"my_store\",\n",
+    ")\n",
+    "\n",
+    "embeddings = CacheBackedEmbeddings.from_bytes_store(\n",
+    "    underlying_embeddings=OpenAIEmbeddings(), document_embedding_cache=store\n",
+    ")"
+   ],
+   "metadata": {
+    "collapsed": false
+   }
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": ".venv",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.11.4"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}

libs/community/langchain_community/storage/__init__.py

@@ -22,6 +22,9 @@ if TYPE_CHECKING:
         AstraDBByteStore,
         AstraDBStore,
     )
+    from langchain_community.storage.cassandra import (
+        CassandraByteStore,
+    )
     from langchain_community.storage.mongodb import (
         MongoDBStore,
     )
@@ -36,6 +39,7 @@ if TYPE_CHECKING:
 __all__ = [
     "AstraDBByteStore",
     "AstraDBStore",
+    "CassandraByteStore",
     "MongoDBStore",
     "RedisStore",
     "UpstashRedisByteStore",
@@ -45,6 +49,7 @@ __all__ = [
 _module_lookup = {
     "AstraDBByteStore": "langchain_community.storage.astradb",
     "AstraDBStore": "langchain_community.storage.astradb",
+    "CassandraByteStore": "langchain_community.storage.cassandra",
     "MongoDBStore": "langchain_community.storage.mongodb",
     "RedisStore": "langchain_community.storage.redis",
     "UpstashRedisByteStore": "langchain_community.storage.upstash_redis",

libs/community/tests/unit_tests/storage/test_imports.py

@@ -3,6 +3,7 @@ from langchain_community.storage import __all__, _module_lookup
 EXPECTED_ALL = [
     "AstraDBStore",
     "AstraDBByteStore",
+    "CassandraByteStore",
     "MongoDBStore",
     "RedisStore",
     "UpstashRedisByteStore",