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 how-to guide shows how to use Postgres as the backend for persisting checkpoint state using the langgraph-checkpoint-postgres library.
For demonstration purposes we add persistence to the pre-built create react agent.
In general, you can add a checkpointer to any custom graph that you build like this:
from langgraph.graph import StateGraph
builder = StateGraph(....)
# ... define the graph
checkpointer = # postgres checkpointer (see examples below)
graph = builder.compile(checkpointer=checkpointer)
...
Setup¶
You will need access to a postgres instance. There are many resources online that can help you set up a postgres instance.
Next, let's install the required packages and set our API keys
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")
Set up LangSmith for LangGraph development
Sign up for LangSmith to quickly spot issues and improve the performance of your LangGraph projects. LangSmith lets you use trace data to debug, test, and monitor your LLM apps built with LangGraph — read more about how to get started here.
Define model and tools for the graph¶
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.
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
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)
{'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})]}
{'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
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)
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
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))
[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¶
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)
{'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¶
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)
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¶
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)]
[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)]