mirror of
https://github.com/langchain-ai/langgraph.git
synced 2026-08-20 06:35:46 +02:00
102 lines
2.9 KiB
Markdown
102 lines
2.9 KiB
Markdown
# LangGraph Checkpoint Postgres
|
|
|
|
Implementation of LangGraph CheckpointSaver that uses Postgres.
|
|
|
|
## Usage
|
|
|
|
> [!IMPORTANT]
|
|
> When using Postgres checkpointers for the first time, make sure to call `.setup()` method on them to create required tables. See example below.
|
|
|
|
> [!IMPORTANT]
|
|
> When manually creating Postgres connections and passing them to `PostgresSaver` or `AsyncPostgresSaver`, make sure to include `autocommit=True` and `row_factory=dict_row` (`from psycopg.rows import dict_row`). See a full example in this [how-to guide](https://langchain-ai.github.io/langgraph/how-tos/persistence_postgres/).
|
|
|
|
```python
|
|
from langgraph.checkpoint.postgres import PostgresSaver
|
|
|
|
write_config = {"configurable": {"thread_id": "1", "checkpoint_ns": ""}}
|
|
read_config = {"configurable": {"thread_id": "1"}}
|
|
|
|
DB_URI = "postgres://postgres:postgres@localhost:5432/postgres?sslmode=disable"
|
|
with PostgresSaver.from_conn_string(DB_URI) as checkpointer:
|
|
# call .setup() the first time you're using the checkpointer
|
|
checkpointer.setup()
|
|
checkpoint = {
|
|
"v": 1,
|
|
"ts": "2024-07-31T20:14:19.804150+00:00",
|
|
"id": "1ef4f797-8335-6428-8001-8a1503f9b875",
|
|
"channel_values": {
|
|
"my_key": "meow",
|
|
"node": "node"
|
|
},
|
|
"channel_versions": {
|
|
"__start__": 2,
|
|
"my_key": 3,
|
|
"start:node": 3,
|
|
"node": 3
|
|
},
|
|
"versions_seen": {
|
|
"__input__": {},
|
|
"__start__": {
|
|
"__start__": 1
|
|
},
|
|
"node": {
|
|
"start:node": 2
|
|
}
|
|
},
|
|
"pending_sends": [],
|
|
"current_tasks": {}
|
|
}
|
|
|
|
# store checkpoint
|
|
checkpointer.put(write_config, checkpoint, {}, {})
|
|
|
|
# load checkpoint
|
|
checkpointer.get(read_config)
|
|
|
|
# list checkpoints
|
|
list(checkpointer.list(read_config))
|
|
```
|
|
|
|
### Async
|
|
|
|
```python
|
|
from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
|
|
|
|
async with AsyncPostgresSaver.from_conn_string(DB_URI) as checkpointer:
|
|
checkpoint = {
|
|
"v": 1,
|
|
"ts": "2024-07-31T20:14:19.804150+00:00",
|
|
"id": "1ef4f797-8335-6428-8001-8a1503f9b875",
|
|
"channel_values": {
|
|
"my_key": "meow",
|
|
"node": "node"
|
|
},
|
|
"channel_versions": {
|
|
"__start__": 2,
|
|
"my_key": 3,
|
|
"start:node": 3,
|
|
"node": 3
|
|
},
|
|
"versions_seen": {
|
|
"__input__": {},
|
|
"__start__": {
|
|
"__start__": 1
|
|
},
|
|
"node": {
|
|
"start:node": 2
|
|
}
|
|
},
|
|
"pending_sends": [],
|
|
"current_tasks": {}
|
|
}
|
|
|
|
# store checkpoint
|
|
await checkpointer.aput(write_config, checkpoint, {}, {})
|
|
|
|
# load checkpoint
|
|
await checkpointer.aget(read_config)
|
|
|
|
# list checkpoints
|
|
[c async for c in checkpointer.alist(read_config)]
|
|
```
|