Postgres backend

PostgresStore persists state to a PostgreSQL table with the same interface as the in-memory Store. Values are stored as msgpack bytes (the same wire format as the Rust core), so state is durable, shared across processes and machines, and readable by any msgpack consumer.

pip install "swarmstate[postgres]"
# or: uv add "swarmstate[postgres]"

Use it like a Store

from swarmstate.backends.postgres import PostgresStore

store = PostgresStore("postgresql://user:pass@host:5432/db")
store.set("workflow", "onboarding", {"step": 3})
store.get("workflow", "onboarding")     # -> {"step": 3}

It implements the full interface (set, get, contains, delete, keys, namespaces, clear, len(store), snapshot() / restore()), plus close().

Durable, shared LangGraph checkpoints

PostgresStore drops straight into SwarmStateSaver, so LangGraph checkpoints live in your existing Postgres, survive restarts, and are shared across workers:

from swarmstate.backends.postgres import PostgresStore
from swarmstate.integrations.langgraph import SwarmStateSaver

saver = SwarmStateSaver(PostgresStore("postgresql://user:pass@host/db"))
graph = builder.compile(checkpointer=saver)

Which backend?

Backend	Persistent	Shared across processes	Needs a server
Store (memory)	no	no	no
DiskStore (SQLite)	yes (a file)	one machine	no
RedisStore	yes	yes (networked)	yes (Redis)
PostgresStore	yes	yes (networked)	yes (Postgres)

Layout & parameters

A single table (ns text, k text, v bytea, primary key (ns, k)) (default name swarmstate_kv); v is msgpack bytes.

Parameter	Default	Description
dsn	postgresql:///swarmstate	libpq connection string
conn	None	pass an existing psycopg connection instead of a DSN
table	"swarmstate_kv"	table name (validated identifier)
codec	"msgpack"	value serialization (stable, cross-language)