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How to use Postgres checkpointer for persistence

When creating LangGraph agents, you can also set them up so that they persist their state. This allows you to do things like interact with an agent multiple times and have it remember previous interactions.

This example shows how to use Postgres as the backend for persisting checkpoint state using langgraph-checkpoint-postgres library.

To start a Postgres database to work with you can do the following:

$ cd libs/langgraph
$ make start-postgres

Setup environment

In [1]:
%%capture --no-stderr
%pip install -U psycopg psycopg-pool langgraph langgraph-checkpoint-postgres
In [2]:
import getpass
import os


def _set_env(var: str):
    if not os.environ.get(var):
        os.environ[var] = getpass.getpass(f"{var}: ")


_set_env("OPENAI_API_KEY")
OPENAI_API_KEY:  ········

Setup model and tools for the graph

In [3]:
from typing import Literal

from langchain_core.tools import tool
from langchain_openai import ChatOpenAI
from langgraph.prebuilt import create_react_agent
from langgraph.checkpoint.postgres import PostgresSaver
from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver


@tool
def get_weather(city: Literal["nyc", "sf"]):
    """Use this to get weather information."""
    if city == "nyc":
        return "It might be cloudy in nyc"
    elif city == "sf":
        return "It's always sunny in sf"
    else:
        raise AssertionError("Unknown city")


tools = [get_weather]
model = ChatOpenAI(model_name="gpt-4o-mini", temperature=0)

Use sync connection

This sets up a synchronous connection to the database.

Synchronous connections execute operations in a blocking manner, meaning each operation waits for completion before moving to the next one. The DB_URI is the database connection URI, with the protocol used for connecting to a PostgreSQL database, authentication, and host where database is running. The connection_kwargs dictionary defines additional parameters for the database connection.

In [4]:
DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable"
In [5]:
connection_kwargs = {
    "autocommit": True,
    "prepare_threshold": 0,
}

With a connection pool

This manages a pool of reusable database connections:

  • Advantages: Efficient resource utilization, improved performance for frequent connections
  • Best for: Applications with many short-lived database operations
In [6]:
from psycopg_pool import ConnectionPool

with ConnectionPool(
    # Example configuration
    conninfo=DB_URI,
    max_size=20,
    kwargs=connection_kwargs,
) as pool:
    checkpointer = PostgresSaver(pool)

    # NOTE: you need to call .setup() the first time you're using your checkpointer
    checkpointer.setup()

    graph = create_react_agent(model, tools=tools, checkpointer=checkpointer)
    config = {"configurable": {"thread_id": "1"}}
    res = graph.invoke({"messages": [("human", "what's the weather in sf")]}, config)
    checkpoint = checkpointer.get(config)
In [7]:
res
Out [7]:
{'messages': [HumanMessage(content="what's the weather in sf", id='735b7deb-b0fe-4ad5-8920-2a3c69bbe9f7'),
  AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_lJHMDYgfgRdiEAGfFsEhqqKV', 'function': {'arguments': '{"city":"sf"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 14, 'prompt_tokens': 57, 'total_tokens': 71}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-c56b3e04-08a9-4a59-b3f5-ee52d0ef0656-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'sf'}, 'id': 'call_lJHMDYgfgRdiEAGfFsEhqqKV', 'type': 'tool_call'}], usage_metadata={'input_tokens': 57, 'output_tokens': 14, 'total_tokens': 71}),
  ToolMessage(content="It's always sunny in sf", name='get_weather', id='0644bf7b-4d1b-4ebe-afa1-d2169ccce582', tool_call_id='call_lJHMDYgfgRdiEAGfFsEhqqKV'),
  AIMessage(content='The weather in San Francisco is always sunny!', response_metadata={'token_usage': {'completion_tokens': 10, 'prompt_tokens': 84, 'total_tokens': 94}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'stop', 'logprobs': None}, id='run-1ed9b8d0-9b50-4b87-b3a2-9860f51e9fd1-0', usage_metadata={'input_tokens': 84, 'output_tokens': 10, 'total_tokens': 94})]}
In [8]:
checkpoint
Out [8]:
{'v': 1,
 'id': '1ef559b7-3b19-6ce8-8003-18d0f60634be',
 'ts': '2024-08-08T15:32:42.108605+00:00',
 'current_tasks': {},
 'pending_sends': [],
 'versions_seen': {'agent': {'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8',
   'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'},
  'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'},
  '__input__': {},
  '__start__': {'__start__': '00000000000000000000000000000001.ab89befb52cc0e91e106ef7f500ea033'}},
 'channel_versions': {'agent': '00000000000000000000000000000005.065d90dd7f7cd091f0233855210bb2af',
  'tools': '00000000000000000000000000000005.',
  'messages': '00000000000000000000000000000005.b9adc75836c78af94af1d6811340dd13',
  '__start__': '00000000000000000000000000000002.',
  'start:agent': '00000000000000000000000000000003.',
  'branch:agent:should_continue:tools': '00000000000000000000000000000004.'},
 'channel_values': {'agent': 'agent',
  'messages': [HumanMessage(content="what's the weather in sf", id='735b7deb-b0fe-4ad5-8920-2a3c69bbe9f7'),
   AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_lJHMDYgfgRdiEAGfFsEhqqKV', 'function': {'arguments': '{"city":"sf"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 14, 'prompt_tokens': 57, 'total_tokens': 71}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-c56b3e04-08a9-4a59-b3f5-ee52d0ef0656-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'sf'}, 'id': 'call_lJHMDYgfgRdiEAGfFsEhqqKV', 'type': 'tool_call'}], usage_metadata={'input_tokens': 57, 'output_tokens': 14, 'total_tokens': 71}),
   ToolMessage(content="It's always sunny in sf", name='get_weather', id='0644bf7b-4d1b-4ebe-afa1-d2169ccce582', tool_call_id='call_lJHMDYgfgRdiEAGfFsEhqqKV'),
   AIMessage(content='The weather in San Francisco is always sunny!', response_metadata={'token_usage': {'completion_tokens': 10, 'prompt_tokens': 84, 'total_tokens': 94}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'stop', 'logprobs': None}, id='run-1ed9b8d0-9b50-4b87-b3a2-9860f51e9fd1-0', usage_metadata={'input_tokens': 84, 'output_tokens': 10, 'total_tokens': 94})]}}

With a connection

This creates a single, dedicated connection to the database:

  • Advantages: Simple to use, suitable for longer transactions
  • Best for: Applications with fewer, longer-lived database operations
In [9]:
from psycopg import Connection


with Connection.connect(DB_URI, **connection_kwargs) as conn:
    checkpointer = PostgresSaver(conn)
    # NOTE: you need to call .setup() the first time you're using your checkpointer
    # checkpointer.setup()
    graph = create_react_agent(model, tools=tools, checkpointer=checkpointer)
    config = {"configurable": {"thread_id": "2"}}
    res = graph.invoke({"messages": [("human", "what's the weather in sf")]}, config)

    checkpoint_tuple = checkpointer.get_tuple(config)
In [10]:
checkpoint_tuple
Out [10]:
CheckpointTuple(config={'configurable': {'thread_id': '2', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-4650-6bfc-8003-1c5488f19318'}}, checkpoint={'v': 1, 'id': '1ef559b7-4650-6bfc-8003-1c5488f19318', 'ts': '2024-08-08T15:32:43.284551+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8', 'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.ab89befb52cc0e91e106ef7f500ea033'}}, 'channel_versions': {'agent': '00000000000000000000000000000005.065d90dd7f7cd091f0233855210bb2af', 'tools': '00000000000000000000000000000005.', 'messages': '00000000000000000000000000000005.af9f229d2c4e14f4866eb37f72ec39f6', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000004.'}, 'channel_values': {'agent': 'agent', 'messages': [HumanMessage(content="what's the weather in sf", id='7a14f96c-2d88-454f-9520-0e0287a4abbb'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_NcL4dBTYu4kSPGMKdxztdpjN', 'function': {'arguments': '{"city":"sf"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 14, 'prompt_tokens': 57, 'total_tokens': 71}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-39adbf2c-36ef-40f6-9cad-8e1f8167fc19-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'sf'}, 'id': 'call_NcL4dBTYu4kSPGMKdxztdpjN', 'type': 'tool_call'}], usage_metadata={'input_tokens': 57, 'output_tokens': 14, 'total_tokens': 71}), ToolMessage(content="It's always sunny in sf", name='get_weather', id='c9f82354-3225-40a8-bf54-81f3e199043b', tool_call_id='call_NcL4dBTYu4kSPGMKdxztdpjN'), AIMessage(content='The weather in San Francisco is always sunny!', response_metadata={'token_usage': {'completion_tokens': 10, 'prompt_tokens': 84, 'total_tokens': 94}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'stop', 'logprobs': None}, id='run-83888be3-d681-42ca-ad67-e2f5ee8550de-0', usage_metadata={'input_tokens': 84, 'output_tokens': 10, 'total_tokens': 94})]}}, metadata={'step': 3, 'source': 'loop', 'writes': {'agent': {'messages': [AIMessage(content='The weather in San Francisco is always sunny!', response_metadata={'logprobs': None, 'model_name': 'gpt-4o-mini-2024-07-18', 'token_usage': {'total_tokens': 94, 'prompt_tokens': 84, 'completion_tokens': 10}, 'finish_reason': 'stop', 'system_fingerprint': 'fp_48196bc67a'}, id='run-83888be3-d681-42ca-ad67-e2f5ee8550de-0', usage_metadata={'input_tokens': 84, 'output_tokens': 10, 'total_tokens': 94})]}}}, parent_config={'configurable': {'thread_id': '2', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-4087-681a-8002-88a5738f76f1'}}, pending_writes=[])

With a connection string

This creates a connection based on a connection string:

  • Advantages: Simplicity, encapsulates connection details
  • Best for: Quick setup or when connection details are provided as a string
In [11]:
with PostgresSaver.from_conn_string(DB_URI) as checkpointer:
    graph = create_react_agent(model, tools=tools, checkpointer=checkpointer)
    config = {"configurable": {"thread_id": "3"}}
    res = graph.invoke({"messages": [("human", "what's the weather in sf")]}, config)

    checkpoint_tuples = list(checkpointer.list(config))
In [12]:
checkpoint_tuples
Out [12]:
[CheckpointTuple(config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-5024-6476-8003-cf0a750e6b37'}}, checkpoint={'v': 1, 'id': '1ef559b7-5024-6476-8003-cf0a750e6b37', 'ts': '2024-08-08T15:32:44.314900+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8', 'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.ab89befb52cc0e91e106ef7f500ea033'}}, 'channel_versions': {'agent': '00000000000000000000000000000005.065d90dd7f7cd091f0233855210bb2af', 'tools': '00000000000000000000000000000005.', 'messages': '00000000000000000000000000000005.3f8b8d9923575b911e17157008ab75ac', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000004.'}, 'channel_values': {'agent': 'agent', 'messages': [HumanMessage(content="what's the weather in sf", id='5bf79d15-6332-4bf5-89bd-ee192b31ed84'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'function': {'arguments': '{"city":"sf"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 14, 'prompt_tokens': 57, 'total_tokens': 71}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_507c9469a1', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-2958adc7-f6a4-415d-ade1-5ee77e0b9276-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'sf'}, 'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'type': 'tool_call'}], usage_metadata={'input_tokens': 57, 'output_tokens': 14, 'total_tokens': 71}), ToolMessage(content="It's always sunny in sf", name='get_weather', id='cac4f90a-dc3e-4bfa-940f-1c630289a583', tool_call_id='call_9y3q1BiwW7zGh2gk2faInTRk'), AIMessage(content='The weather in San Francisco is always sunny!', response_metadata={'token_usage': {'completion_tokens': 10, 'prompt_tokens': 84, 'total_tokens': 94}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'stop', 'logprobs': None}, id='run-97d3fb7a-3d2e-4090-84f4-dafdfe44553f-0', usage_metadata={'input_tokens': 84, 'output_tokens': 10, 'total_tokens': 94})]}}, metadata={'step': 3, 'source': 'loop', 'writes': {'agent': {'messages': [AIMessage(content='The weather in San Francisco is always sunny!', response_metadata={'logprobs': None, 'model_name': 'gpt-4o-mini-2024-07-18', 'token_usage': {'total_tokens': 94, 'prompt_tokens': 84, 'completion_tokens': 10}, 'finish_reason': 'stop', 'system_fingerprint': 'fp_48196bc67a'}, id='run-97d3fb7a-3d2e-4090-84f4-dafdfe44553f-0', usage_metadata={'input_tokens': 84, 'output_tokens': 10, 'total_tokens': 94})]}}}, parent_config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-4b3d-6430-8002-b5c99d2eb4db'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-4b3d-6430-8002-b5c99d2eb4db'}}, checkpoint={'v': 1, 'id': '1ef559b7-4b3d-6430-8002-b5c99d2eb4db', 'ts': '2024-08-08T15:32:43.800857+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.ab89befb52cc0e91e106ef7f500ea033'}}, 'channel_versions': {'agent': '00000000000000000000000000000004.', 'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8', 'messages': '00000000000000000000000000000004.1195f50946feaedb0bae1fdbfadc806b', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000004.'}, 'channel_values': {'tools': 'tools', 'messages': [HumanMessage(content="what's the weather in sf", id='5bf79d15-6332-4bf5-89bd-ee192b31ed84'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'function': {'arguments': '{"city":"sf"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 14, 'prompt_tokens': 57, 'total_tokens': 71}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_507c9469a1', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-2958adc7-f6a4-415d-ade1-5ee77e0b9276-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'sf'}, 'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'type': 'tool_call'}], usage_metadata={'input_tokens': 57, 'output_tokens': 14, 'total_tokens': 71}), ToolMessage(content="It's always sunny in sf", name='get_weather', id='cac4f90a-dc3e-4bfa-940f-1c630289a583', tool_call_id='call_9y3q1BiwW7zGh2gk2faInTRk')]}}, metadata={'step': 2, 'source': 'loop', 'writes': {'tools': {'messages': [ToolMessage(content="It's always sunny in sf", name='get_weather', id='cac4f90a-dc3e-4bfa-940f-1c630289a583', tool_call_id='call_9y3q1BiwW7zGh2gk2faInTRk')]}}}, parent_config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-4b30-6078-8001-eaf8c9bd8844'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-4b30-6078-8001-eaf8c9bd8844'}}, checkpoint={'v': 1, 'id': '1ef559b7-4b30-6078-8001-eaf8c9bd8844', 'ts': '2024-08-08T15:32:43.795440+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.ab89befb52cc0e91e106ef7f500ea033'}}, 'channel_versions': {'agent': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af', 'messages': '00000000000000000000000000000003.bab5fb3a70876f600f5f2fd46945ce5f', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, 'channel_values': {'agent': 'agent', 'messages': [HumanMessage(content="what's the weather in sf", id='5bf79d15-6332-4bf5-89bd-ee192b31ed84'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'function': {'arguments': '{"city":"sf"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 14, 'prompt_tokens': 57, 'total_tokens': 71}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_507c9469a1', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-2958adc7-f6a4-415d-ade1-5ee77e0b9276-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'sf'}, 'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'type': 'tool_call'}], usage_metadata={'input_tokens': 57, 'output_tokens': 14, 'total_tokens': 71})], 'branch:agent:should_continue:tools': 'agent'}}, metadata={'step': 1, 'source': 'loop', 'writes': {'agent': {'messages': [AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'type': 'function', 'function': {'name': 'get_weather', 'arguments': '{"city":"sf"}'}}]}, response_metadata={'logprobs': None, 'model_name': 'gpt-4o-mini-2024-07-18', 'token_usage': {'total_tokens': 71, 'prompt_tokens': 57, 'completion_tokens': 14}, 'finish_reason': 'tool_calls', 'system_fingerprint': 'fp_507c9469a1'}, id='run-2958adc7-f6a4-415d-ade1-5ee77e0b9276-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'sf'}, 'id': 'call_9y3q1BiwW7zGh2gk2faInTRk', 'type': 'tool_call'}], usage_metadata={'input_tokens': 57, 'output_tokens': 14, 'total_tokens': 71})]}}}, parent_config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-46d7-6116-8000-8976b7c89a2f'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-46d7-6116-8000-8976b7c89a2f'}}, checkpoint={'v': 1, 'id': '1ef559b7-46d7-6116-8000-8976b7c89a2f', 'ts': '2024-08-08T15:32:43.339573+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.ab89befb52cc0e91e106ef7f500ea033'}}, 'channel_versions': {'messages': '00000000000000000000000000000002.ba0c90d32863686481f7fe5eab9ecdf0', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'channel_values': {'messages': [HumanMessage(content="what's the weather in sf", id='5bf79d15-6332-4bf5-89bd-ee192b31ed84')], 'start:agent': '__start__'}}, metadata={'step': 0, 'source': 'loop', 'writes': None}, parent_config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-46ce-6c64-bfff-ef7fe2663573'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '3', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-46ce-6c64-bfff-ef7fe2663573'}}, checkpoint={'v': 1, 'id': '1ef559b7-46ce-6c64-bfff-ef7fe2663573', 'ts': '2024-08-08T15:32:43.336188+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'__input__': {}}, 'channel_versions': {'__start__': '00000000000000000000000000000001.ab89befb52cc0e91e106ef7f500ea033'}, 'channel_values': {'__start__': {'messages': [['human', "what's the weather in sf"]]}}}, metadata={'step': -1, 'source': 'input', 'writes': {'messages': [['human', "what's the weather in sf"]]}}, parent_config=None, pending_writes=None)]

Use async connection

This sets up an asynchronous connection to the database.

Async connections allow non-blocking database operations. This means other parts of your application can continue running while waiting for database operations to complete. It's particularly useful in high-concurrency scenarios or when dealing with I/O-bound operations.

With a connection pool

In [13]:
from psycopg_pool import AsyncConnectionPool

async with AsyncConnectionPool(
    # Example configuration
    conninfo=DB_URI,
    max_size=20,
    kwargs=connection_kwargs,
) as pool:
    checkpointer = AsyncPostgresSaver(pool)

    # NOTE: you need to call .setup() the first time you're using your checkpointer
    # await checkpointer.setup()

    graph = create_react_agent(model, tools=tools, checkpointer=checkpointer)
    config = {"configurable": {"thread_id": "4"}}
    res = await graph.ainvoke(
        {"messages": [("human", "what's the weather in nyc")]}, config
    )

    checkpoint = await checkpointer.aget(config)
/Users/vadymbarda/.virtualenvs/langgraph-postgres/lib/python3.11/site-packages/psycopg_pool/pool_async.py:138: RuntimeWarning: opening the async pool AsyncConnectionPool in the constructor is deprecated and will not be supported anymore in a future release. Please use `await pool.open()`, or use the pool as context manager using: `async with AsyncConnectionPool(...) as pool: `...
  warnings.warn(
In [14]:
checkpoint
Out [14]:
{'v': 1,
 'id': '1ef559b7-5cc9-6460-8003-8655824c0944',
 'ts': '2024-08-08T15:32:45.640793+00:00',
 'current_tasks': {},
 'pending_sends': [],
 'versions_seen': {'agent': {'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8',
   'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'},
  'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'},
  '__input__': {},
  '__start__': {'__start__': '00000000000000000000000000000001.0e148ae3debe753278387e84f786e863'}},
 'channel_versions': {'agent': '00000000000000000000000000000005.065d90dd7f7cd091f0233855210bb2af',
  'tools': '00000000000000000000000000000005.',
  'messages': '00000000000000000000000000000005.d869fc7231619df0db74feed624efe41',
  '__start__': '00000000000000000000000000000002.',
  'start:agent': '00000000000000000000000000000003.',
  'branch:agent:should_continue:tools': '00000000000000000000000000000004.'},
 'channel_values': {'agent': 'agent',
  'messages': [HumanMessage(content="what's the weather in nyc", id='d883b8a0-99de-486d-91a2-bcfa7f25dc05'),
   AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_H6TAYfyd6AnaCrkQGs6Q2fVp', 'function': {'arguments': '{"city":"nyc"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 15, 'prompt_tokens': 58, 'total_tokens': 73}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-6f542f84-ad73-444c-8ef7-b5ea75a2e09b-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'nyc'}, 'id': 'call_H6TAYfyd6AnaCrkQGs6Q2fVp', 'type': 'tool_call'}], usage_metadata={'input_tokens': 58, 'output_tokens': 15, 'total_tokens': 73}),
   ToolMessage(content='It might be cloudy in nyc', name='get_weather', id='c0e52254-77a4-4ea9-a2b7-61dd2d65ec68', tool_call_id='call_H6TAYfyd6AnaCrkQGs6Q2fVp'),
   AIMessage(content='The weather in NYC might be cloudy.', response_metadata={'token_usage': {'completion_tokens': 9, 'prompt_tokens': 88, 'total_tokens': 97}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'stop', 'logprobs': None}, id='run-977140d4-7582-40c3-b2b6-31b542c430a3-0', usage_metadata={'input_tokens': 88, 'output_tokens': 9, 'total_tokens': 97})]}}

With a connection

In [15]:
from psycopg import AsyncConnection

async with await AsyncConnection.connect(DB_URI, **connection_kwargs) as conn:
    checkpointer = AsyncPostgresSaver(conn)
    graph = create_react_agent(model, tools=tools, checkpointer=checkpointer)
    config = {"configurable": {"thread_id": "5"}}
    res = await graph.ainvoke(
        {"messages": [("human", "what's the weather in nyc")]}, config
    )
    checkpoint_tuple = await checkpointer.aget_tuple(config)
In [16]:
checkpoint_tuple
Out [16]:
CheckpointTuple(config={'configurable': {'thread_id': '5', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-65b4-60ca-8003-1ef4b620559a'}}, checkpoint={'v': 1, 'id': '1ef559b7-65b4-60ca-8003-1ef4b620559a', 'ts': '2024-08-08T15:32:46.575814+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8', 'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0e148ae3debe753278387e84f786e863'}}, 'channel_versions': {'agent': '00000000000000000000000000000005.065d90dd7f7cd091f0233855210bb2af', 'tools': '00000000000000000000000000000005.', 'messages': '00000000000000000000000000000005.1557a6006d58f736d5cb2dd5c5f10111', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000004.'}, 'channel_values': {'agent': 'agent', 'messages': [HumanMessage(content="what's the weather in nyc", id='935e7732-b288-49bd-9ec2-1f7610cc38cb'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_94KtjtPmsiaj7T8yXvL7Ef31', 'function': {'arguments': '{"city":"nyc"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 15, 'prompt_tokens': 58, 'total_tokens': 73}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-790c929a-7982-49e7-af67-2cbe4a86373b-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'nyc'}, 'id': 'call_94KtjtPmsiaj7T8yXvL7Ef31', 'type': 'tool_call'}], usage_metadata={'input_tokens': 58, 'output_tokens': 15, 'total_tokens': 73}), ToolMessage(content='It might be cloudy in nyc', name='get_weather', id='b2dc1073-abc4-4492-8982-434a7e32e445', tool_call_id='call_94KtjtPmsiaj7T8yXvL7Ef31'), AIMessage(content='The weather in NYC might be cloudy.', response_metadata={'token_usage': {'completion_tokens': 9, 'prompt_tokens': 88, 'total_tokens': 97}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'stop', 'logprobs': None}, id='run-7e8a7f16-d8e1-457a-89f3-192102396449-0', usage_metadata={'input_tokens': 88, 'output_tokens': 9, 'total_tokens': 97})]}}, metadata={'step': 3, 'source': 'loop', 'writes': {'agent': {'messages': [AIMessage(content='The weather in NYC might be cloudy.', response_metadata={'logprobs': None, 'model_name': 'gpt-4o-mini-2024-07-18', 'token_usage': {'total_tokens': 97, 'prompt_tokens': 88, 'completion_tokens': 9}, 'finish_reason': 'stop', 'system_fingerprint': 'fp_48196bc67a'}, id='run-7e8a7f16-d8e1-457a-89f3-192102396449-0', usage_metadata={'input_tokens': 88, 'output_tokens': 9, 'total_tokens': 97})]}}}, parent_config={'configurable': {'thread_id': '5', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-62ae-6128-8002-c04af82bcd41'}}, pending_writes=[])

With a connection string

In [17]:
async with AsyncPostgresSaver.from_conn_string(DB_URI) as checkpointer:
    graph = create_react_agent(model, tools=tools, checkpointer=checkpointer)
    config = {"configurable": {"thread_id": "6"}}
    res = await graph.ainvoke(
        {"messages": [("human", "what's the weather in nyc")]}, config
    )
    checkpoint_tuples = [c async for c in checkpointer.alist(config)]
In [18]:
checkpoint_tuples
Out [18]:
[CheckpointTuple(config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-723c-67de-8003-63bd4eab35af'}}, checkpoint={'v': 1, 'id': '1ef559b7-723c-67de-8003-63bd4eab35af', 'ts': '2024-08-08T15:32:47.890003+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8', 'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0e148ae3debe753278387e84f786e863'}}, 'channel_versions': {'agent': '00000000000000000000000000000005.065d90dd7f7cd091f0233855210bb2af', 'tools': '00000000000000000000000000000005.', 'messages': '00000000000000000000000000000005.b6fe2a26011590cfe8fd6a39151a9e92', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000004.'}, 'channel_values': {'agent': 'agent', 'messages': [HumanMessage(content="what's the weather in nyc", id='977ddb90-9991-44cb-9f73-361c6dd21396'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'function': {'arguments': '{"city":"nyc"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 15, 'prompt_tokens': 58, 'total_tokens': 73}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-47b10c48-4db3-46d8-b4fa-e021818e01c5-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'nyc'}, 'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'type': 'tool_call'}], usage_metadata={'input_tokens': 58, 'output_tokens': 15, 'total_tokens': 73}), ToolMessage(content='It might be cloudy in nyc', name='get_weather', id='798c520f-4f9a-4f6d-a389-da721eb4d4ce', tool_call_id='call_QIFCuh4zfP9owpjToycJiZf7'), AIMessage(content='The weather in NYC might be cloudy.', response_metadata={'token_usage': {'completion_tokens': 9, 'prompt_tokens': 88, 'total_tokens': 97}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'stop', 'logprobs': None}, id='run-4a34e05d-8bcf-41ad-adc3-715919fde64c-0', usage_metadata={'input_tokens': 88, 'output_tokens': 9, 'total_tokens': 97})]}}, metadata={'step': 3, 'source': 'loop', 'writes': {'agent': {'messages': [AIMessage(content='The weather in NYC might be cloudy.', response_metadata={'logprobs': None, 'model_name': 'gpt-4o-mini-2024-07-18', 'token_usage': {'total_tokens': 97, 'prompt_tokens': 88, 'completion_tokens': 9}, 'finish_reason': 'stop', 'system_fingerprint': 'fp_48196bc67a'}, id='run-4a34e05d-8bcf-41ad-adc3-715919fde64c-0', usage_metadata={'input_tokens': 88, 'output_tokens': 9, 'total_tokens': 97})]}}}, parent_config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-6bf5-63c6-8002-ed990dbbc96e'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-6bf5-63c6-8002-ed990dbbc96e'}}, checkpoint={'v': 1, 'id': '1ef559b7-6bf5-63c6-8002-ed990dbbc96e', 'ts': '2024-08-08T15:32:47.231667+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'tools': {'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0e148ae3debe753278387e84f786e863'}}, 'channel_versions': {'agent': '00000000000000000000000000000004.', 'tools': '00000000000000000000000000000004.022986cd20ae85c77ea298a383f69ba8', 'messages': '00000000000000000000000000000004.c9074f2a41f05486b5efb86353dc75c0', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000004.'}, 'channel_values': {'tools': 'tools', 'messages': [HumanMessage(content="what's the weather in nyc", id='977ddb90-9991-44cb-9f73-361c6dd21396'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'function': {'arguments': '{"city":"nyc"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 15, 'prompt_tokens': 58, 'total_tokens': 73}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-47b10c48-4db3-46d8-b4fa-e021818e01c5-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'nyc'}, 'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'type': 'tool_call'}], usage_metadata={'input_tokens': 58, 'output_tokens': 15, 'total_tokens': 73}), ToolMessage(content='It might be cloudy in nyc', name='get_weather', id='798c520f-4f9a-4f6d-a389-da721eb4d4ce', tool_call_id='call_QIFCuh4zfP9owpjToycJiZf7')]}}, metadata={'step': 2, 'source': 'loop', 'writes': {'tools': {'messages': [ToolMessage(content='It might be cloudy in nyc', name='get_weather', id='798c520f-4f9a-4f6d-a389-da721eb4d4ce', tool_call_id='call_QIFCuh4zfP9owpjToycJiZf7')]}}}, parent_config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-6be0-6926-8001-1a8ce73baf9e'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-6be0-6926-8001-1a8ce73baf9e'}}, checkpoint={'v': 1, 'id': '1ef559b7-6be0-6926-8001-1a8ce73baf9e', 'ts': '2024-08-08T15:32:47.223198+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'agent': {'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, '__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0e148ae3debe753278387e84f786e863'}}, 'channel_versions': {'agent': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af', 'messages': '00000000000000000000000000000003.097b5407d709b297591f1ef5d50c8368', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000003.', 'branch:agent:should_continue:tools': '00000000000000000000000000000003.065d90dd7f7cd091f0233855210bb2af'}, 'channel_values': {'agent': 'agent', 'messages': [HumanMessage(content="what's the weather in nyc", id='977ddb90-9991-44cb-9f73-361c6dd21396'), AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'function': {'arguments': '{"city":"nyc"}', 'name': 'get_weather'}, 'type': 'function'}]}, response_metadata={'token_usage': {'completion_tokens': 15, 'prompt_tokens': 58, 'total_tokens': 73}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_48196bc67a', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run-47b10c48-4db3-46d8-b4fa-e021818e01c5-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'nyc'}, 'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'type': 'tool_call'}], usage_metadata={'input_tokens': 58, 'output_tokens': 15, 'total_tokens': 73})], 'branch:agent:should_continue:tools': 'agent'}}, metadata={'step': 1, 'source': 'loop', 'writes': {'agent': {'messages': [AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'type': 'function', 'function': {'name': 'get_weather', 'arguments': '{"city":"nyc"}'}}]}, response_metadata={'logprobs': None, 'model_name': 'gpt-4o-mini-2024-07-18', 'token_usage': {'total_tokens': 73, 'prompt_tokens': 58, 'completion_tokens': 15}, 'finish_reason': 'tool_calls', 'system_fingerprint': 'fp_48196bc67a'}, id='run-47b10c48-4db3-46d8-b4fa-e021818e01c5-0', tool_calls=[{'name': 'get_weather', 'args': {'city': 'nyc'}, 'id': 'call_QIFCuh4zfP9owpjToycJiZf7', 'type': 'tool_call'}], usage_metadata={'input_tokens': 58, 'output_tokens': 15, 'total_tokens': 73})]}}}, parent_config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-663d-60b4-8000-10a8922bffbf'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-663d-60b4-8000-10a8922bffbf'}}, checkpoint={'v': 1, 'id': '1ef559b7-663d-60b4-8000-10a8922bffbf', 'ts': '2024-08-08T15:32:46.631935+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0e148ae3debe753278387e84f786e863'}}, 'channel_versions': {'messages': '00000000000000000000000000000002.2a79db8da664e437bdb25ea804457ca7', '__start__': '00000000000000000000000000000002.', 'start:agent': '00000000000000000000000000000002.d6f25946c3108fc12f27abbcf9b4cedc'}, 'channel_values': {'messages': [HumanMessage(content="what's the weather in nyc", id='977ddb90-9991-44cb-9f73-361c6dd21396')], 'start:agent': '__start__'}}, metadata={'step': 0, 'source': 'loop', 'writes': None}, parent_config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-6637-6d4e-bfff-6cecf690c3cb'}}, pending_writes=None),
 CheckpointTuple(config={'configurable': {'thread_id': '6', 'checkpoint_ns': '', 'checkpoint_id': '1ef559b7-6637-6d4e-bfff-6cecf690c3cb'}}, checkpoint={'v': 1, 'id': '1ef559b7-6637-6d4e-bfff-6cecf690c3cb', 'ts': '2024-08-08T15:32:46.629806+00:00', 'current_tasks': {}, 'pending_sends': [], 'versions_seen': {'__input__': {}}, 'channel_versions': {'__start__': '00000000000000000000000000000001.0e148ae3debe753278387e84f786e863'}, 'channel_values': {'__start__': {'messages': [['human', "what's the weather in nyc"]]}}}, metadata={'step': -1, 'source': 'input', 'writes': {'messages': [['human', "what's the weather in nyc"]]}}, parent_config=None, pending_writes=None)]
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