docs: update PGVectorStore quickstart (#177)

Co-authored-by: Eugene Yurtsev <[email protected]>

Author: averikitsch

examples/pg_vectorstore.ipynb

@@ -34,7 +34,9 @@
    },
    "outputs": [],
    "source": [
-    "%pip install --upgrade --quiet  langchain-postgres"
+    "%pip install --upgrade --quiet  langchain-postgres\n",
+    "# This tutorial also requires the following dependencies\n",
+    "%pip install --upgrade --quiet  langchain-core langchain-cohere SQLAlchemy"
    ]
   },
   {
@@ -47,14 +49,29 @@
     "## Basic Usage"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This package requires a PostgreSQL database with the `pgvector` extension.\n",
+    "\n",
+    "You can run the following command to spin up a container for a `pgvector` enabled Postgres instance:\n",
+    "\n",
+    "```shell\n",
+    "docker run --name pgvector-container -e POSTGRES_USER=langchain -e POSTGRES_PASSWORD=langchain -e POSTGRES_DB=langchain -p 6024:5432 -d pgvector/pgvector:pg16\n",
+    "```"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "OMvzMWRrR6n7",
    "metadata": {
     "id": "OMvzMWRrR6n7"
    },
    "source": [
-    "### Set the postgres connection url"
+    "### Set the postgres connection url\n",
+    "\n",
+    "`PGVectorStore` can be used with the `asyncpg` and `psycopg3` drivers."
    ]
   },
   {
@@ -66,26 +83,14 @@
    },
    "outputs": [],
    "source": [
-    "# @title Set Your Values Here { display-mode: \"form\" }\n",
-    "POSTGRES_USER = \"postgres-user\"  # @param {type: \"string\"}\n",
-    "POSTGRES_PASSWORD = \"postgres-password\"  # @param {type: \"string\"}\n",
-    "POSTGRES_HOST = \"postgres-host\"  # @param {type: \"string\"}\n",
-    "POSTGRES_PORT = \"postgres-port\"  # @param {type: \"string\"}\n",
-    "POSTGRES_DB = \"postgres-db-name\"  # @param {type: \"string\"}\n",
+    "# @title Set your values or use the defaults to connect to Docker { display-mode: \"form\" }\n",
+    "POSTGRES_USER = \"langchain\"  # @param {type: \"string\"}\n",
+    "POSTGRES_PASSWORD = \"langchain\"  # @param {type: \"string\"}\n",
+    "POSTGRES_HOST = \"localhost\"  # @param {type: \"string\"}\n",
+    "POSTGRES_PORT = \"6024\"  # @param {type: \"string\"}\n",
+    "POSTGRES_DB = \"langchain\"  # @param {type: \"string\"}\n",
     "TABLE_NAME = \"vectorstore\"  # @param {type: \"string\"}\n",
-    "VECTOR_SIZE = 768  # @param {type: \"int\"}\n",
-    "\n",
-    "CONNECTION_STRING = (\n",
-    "    f\"postgresql+asyncpg://{POSTGRES_USER}:{POSTGRES_PASSWORD}@{POSTGRES_HOST}\"\n",
-    "    f\":{POSTGRES_PORT}/{POSTGRES_DB}\"\n",
-    ")"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "*Note:* `PGVectorStore` can only be used with the `postgresql+asyncpg` driver."
+    "VECTOR_SIZE = 768  # @param {type: \"int\"}"
    ]
   },
   {
@@ -111,6 +116,20 @@
     "**Note:** This tutorial demonstrates the async interface. All async methods have corresponding sync methods."
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# See docker command above to launch a Postgres instance with pgvector enabled.\n",
+    "CONNECTION_STRING = (\n",
+    "    f\"postgresql+asyncpg://{POSTGRES_USER}:{POSTGRES_PASSWORD}@{POSTGRES_HOST}\"\n",
+    "    f\":{POSTGRES_PORT}/{POSTGRES_DB}\"\n",
+    ")\n",
+    "# To use psycopg3 driver, set your connection string to `postgresql+psycopg://`"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -374,7 +393,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from langchain_postgres.indexes import IVFFlatIndex\n",
+    "from langchain_postgres.v2.indexes import IVFFlatIndex\n",
     "\n",
     "index = IVFFlatIndex()\n",
     "await store.aapply_vector_index(index)"

examples/vectorstore.ipynb

@@ -21,7 +21,7 @@
     "\n",
     "This code has been ported over from langchain_community. The following changes have been made:\n",
     "\n",
-    "* langchain_postgres works only with psycopg3. Please update your connnecion strings from `postgresql+psycopg2://...` to `postgresql+psycopg://langchain:langchain@...` (yes, it's the driver name is `psycopg` not `psycopg3`, but it'll use `psycopg3`.\n",
+    "* langchain_postgres works only with psycopg3. Please update your connection strings from `postgresql+psycopg2://...` to `postgresql+psycopg://langchain:langchain@...` (yes, it's the driver name is `psycopg` not `psycopg3`, but it'll use `psycopg3`.\n",
     "* The schema of the embedding store and collection have been changed to make add_documents work correctly with user specified ids.\n",
     "* One has to pass an explicit connection object now.\n",
     "\n",