Backends

MemState separates logic from storage. You can start with InMemoryStorage for testing and switch to PostgresStorage or RedisStorage for production without changing your agent logic.

Pro Tip: Dependency Injection

MemState fully supports Dependency Injection. For all backends (Postgres, Redis, SQLite), you can pass an existing connection object instead of a connection string.

PostgreSQL

Uses SQLAlchemy + psycopg. It supports JSONB for efficient querying.

Install the requirements

uvpip

uv add memstate[postgres]

pip install memstate[postgres]

Initialize the storage

syncasync

from memstate import MemoryStore
from memstate.backends.postgres import PostgresStorage

url = "postgresql+psycopg://user:pass@localhost:5432/db_name"
storage = PostgresStorage(url)
store = MemoryStore(storage=storage)

import asyncio
from memstate import AsyncMemoryStore
from memstate.backends.postgres import AsyncPostgresStorage

async def main():
    url = "postgresql+psycopg://user:pass@localhost:5432/db_name"
    storage = AsyncPostgresStorage(url)
    # Important: You must create tables explicitly in async mode
    await store.create_tables()

    store = AsyncMemoryStore(storage=storage)

if __name__ == "__main__":
    asyncio.run(main())

Redis

Stores facts as JSON strings and maintains sets for efficient indexing.

Install the requirements

uvpip

uv add memstate[redis]

pip install memstate[redis]

Initialize the storage

syncasync

from memstate import MemoryStore
from memstate.backends.redis import RedisStorage

storage = RedisStorage("redis://localhost:6379/0")
store = MemoryStore(storage=storage)

import asyncio
from memstate import AsyncMemoryStore
from memstate.backends.redis import AsyncRedisStorage

async def main():
    storage = AsyncRedisStorage("redis://localhost:6379/0")
    store = AsyncMemoryStore(storage=storage)

if __name__ == "__main__":
    asyncio.run(main())

SQLite

The default, zero-config backend. Uses the JSON1 extension for querying.

Install the requirements

For synchronous use, SQLite is built-in.

For async use, you need aiosqlite.

uvpip

uv add memstate[sqlite-async]

pip install memstate[sqlite-async]

Initialize the storage

syncasync

from memstate import MemoryStore, SQLiteStorage

storage = SQLiteStorage("memory.db")
store = MemoryStore(storage=storage)

import asyncio
from memstate import AsyncMemoryStore, AsyncSQLiteStorage

async def main():
    storage = AsyncSQLiteStorage("memory.db")
    # Important: Connect explicitly
    await storage.connect()

    store = AsyncMemoryStore(storage=storage)

if __name__ == "__main__":
    asyncio.run(main())

In-memory

Non-persistent storage. Best for testing and prototyping.

Initialize the storage

syncasync

from memstate import MemoryStore, InMemoryStorage

storage = InMemoryStorage()
store = MemoryStore(storage=storage)

import asyncio
from memstate import AsyncMemoryStore, AsyncInMemoryStorage

async def main():
    storage = AsyncInMemoryStorage()
    store = AsyncMemoryStore(storage=storage)

if __name__ == "__main__":
    asyncio.run(main())