Need session storage for NoSQL DB

Hi Team,

I do have Mongo DB and I would like to save sessions events in the MongoDb and need to retrieve, update and delete the sessions.

Currently session storage is only available in relational DB.

Can I store and retrieve sessions using Mongo. If so can you please provide a sample code in python.

Thanks,
Vasanth

@Vasanthan88

@Vasanthan88 Thanks for opening this request. Could you please share more information about your use case? It will help us understand your request better.
Thank you

@klateefa

@klateefa : I have a mongo DB and I need to store the session using DatabaseSessionService. I need to use mongo DB instead of regular relational database

Something like DatabaseSessionService(Mongo_DB_URL) so that all the sessions, events,app are stored in the Mongo DB and it can be retrieved, created, deleted using default goolge adk api's.

@klateefa

@klateefa

I believe this feature is not implemented yet, from what I can see DatabaseSessionService currently supports SQLite, PostgreSQL and MySQL via SQLAlchemy. Please correct me if I'm wrong.

If adding a MongoDBSessionService aligns with your vision I would be happy to contribute, if so please assign the issue to me and I will start working on it.

Based on what I noticed from the source code, this is the approach I would take:

Subclass BaseSessionService and implement all 5 required methods (create_session, get_session, list_sessions, delete_session, append_event) using motor, the official async MongoDB Python driver.
Use two collections: sessions for metadata and state, and events for event JSON indexed by app_name, user_id, session_id and timestamp.
In append_event, call the existing base helpers _trim_temp_delta_state and _update_session_state to stay consistent with how other session services handle state deltas, then persist the event and update the session document.

Happy to discuss any design decisions before starting.

@klateefa

I believe this feature is not implemented yet, from what I can see DatabaseSessionService currently supports SQLite, PostgreSQL and MySQL via SQLAlchemy. Please correct me if I'm wrong.

If adding a MongoDBSessionService aligns with your vision I would be happy to contribute, if so please assign the issue to me and I will start working on it.

Based on what I noticed from the source code, this is the approach I would take:

Subclass BaseSessionService and implement all 5 required methods (create_session, get_session, list_sessions, delete_session, append_event) using motor, the official async MongoDB Python driver.

Use two collections: sessions for metadata and state, and events for event JSON indexed by app_name, user_id, session_id and timestamp.

In append_event, call the existing base helpers _trim_temp_delta_state and _update_session_state to stay consistent with how other session services handle state deltas, then persist the event and update the session document.

Happy to discuss any design decisions before starting.

The motor will no longer be maintained in a few months, and you can use the official import from Pymongo to Asynchronous MongoClient

@Vasanthan88

Temporary use, waiting for official implementation

"""MongoDB session service implementation for Google ADK."""

import copy
import time
import uuid
from typing import Any, Optional

from pymongo import AsyncMongoClient
from google.adk.events.event import Event
from google.adk.sessions.base_session_service import (
    BaseSessionService,
    GetSessionConfig,
    ListSessionsResponse,
)
from google.adk.sessions.session import Session
from google.adk.sessions.state import State


class MongoSessionService(BaseSessionService):

    def __init__(self, mongo_url: str, db_name: Optional[str] = None, **kwargs: Any):
        client = AsyncMongoClient(mongo_url, **kwargs)
        self.db = client[db_name] if db_name else client.get_default_database()
        self.sessions = self.db.sessions
        self.events = self.db.events
        self.app_states = self.db.app_states
        self.user_states = self.db.user_states

    async def create_session(
        self,
        *,
        app_name: str,
        user_id: str,
        state: Optional[dict[str, Any]] = None,
        session_id: Optional[str] = None,
    ) -> Session:
        sid = session_id or uuid.uuid4().hex
        now = time.time()
        session_state = state or {}

        await self.sessions.insert_one(
            {
                "app_name": app_name,
                "user_id": user_id,
                "id": sid,
                "state": session_state,
                "last_update_time": now,
            }
        )

        session = Session(
            id=sid,
            app_name=app_name,
            user_id=user_id,
            state=session_state,
            events=[],
            last_update_time=now,
        )
        return await self._merge_state(app_name, user_id, copy.deepcopy(session))

    async def get_session(
        self,
        *,
        app_name: str,
        user_id: str,
        session_id: str,
        config: Optional[GetSessionConfig] = None,
    ) -> Optional[Session]:
        filt = {"app_name": app_name, "user_id": user_id, "id": session_id}
        doc = await self.sessions.find_one(filt)
        if not doc:
            return None

        # Get all events for this session
        raw_events = (
            await self.events.find(filt).sort("timestamp", 1).to_list(length=None)
        )
        events = [Event.model_validate_json(e["raw"]) for e in raw_events]

        # Apply config filters if provided
        if config:
            if config.after_timestamp is not None:
                events = [e for e in events if e.timestamp >= config.after_timestamp]
            if config.num_recent_events is not None and events:
                events = events[-config.num_recent_events :]

        session = Session(
            id=session_id,
            app_name=app_name,
            user_id=user_id,
            state=doc.get("state", {}),
            events=events,
            last_update_time=doc.get("last_update_time", 0.0),
        )

        return await self._merge_state(app_name, user_id, copy.deepcopy(session))

    async def list_sessions(
        self, *, app_name: str, user_id: str
    ) -> ListSessionsResponse:
        cursor = self.sessions.find({"app_name": app_name, "user_id": user_id})
        sessions: list[Session] = []
        async for doc in cursor:
            sessions.append(
                Session(
                    id=doc["id"],
                    app_name=app_name,
                    user_id=user_id,
                    state={},
                    events=[],
                    last_update_time=doc.get("last_update_time", 0.0),
                )
            )
        return ListSessionsResponse(sessions=sessions)

    async def delete_session(
        self, *, app_name: str, user_id: str, session_id: str
    ) -> None:
        filt = {"app_name": app_name, "user_id": user_id, "id": session_id}
        await self.sessions.delete_one(filt)
        await self.events.delete_many(filt)

    async def _merge_state(
        self, app_name: str, user_id: str, session: Session
    ) -> Session:
        """Merge app and user state into the session."""
        # Merge app state
        app_states = await self.app_states.find({"app_name": app_name}).to_list(
            length=None
        )
        for state in app_states:
            session.state[State.APP_PREFIX + state["key"]] = state["value"]

        # Merge user state
        user_states = await self.user_states.find(
            {"app_name": app_name, "user_id": user_id}
        ).to_list(length=None)
        for state in user_states:
            session.state[State.USER_PREFIX + state["key"]] = state["value"]

        return session

    async def append_event(self, session: Session, event: Event) -> Event:
        if event.partial:
            return event

        filt = {
            "app_name": session.app_name,
            "user_id": session.user_id,
            "id": session.id,
        }
        doc = await self.sessions.find_one(filt)
        if not doc:
            raise ValueError("session not found")

        if doc.get("last_update_time", 0.0) > session.last_update_time:
            raise ValueError("stale session")

        new_event = await super().append_event(session=session, event=event)

        # Store the event
        await self.events.insert_one(
            {
                **filt,
                "raw": new_event.model_dump_json(),
                "timestamp": new_event.timestamp,
            }
        )

        # Update session state and timestamp
        await self.sessions.update_one(
            filt,
            {
                "$set": {
                    "state": session.state,
                    "last_update_time": session.last_update_time,
                }
            },
        )

        # Process state deltas if present
        if event.actions and event.actions.state_delta:
            for key, value in event.actions.state_delta.items():
                if key.startswith(State.APP_PREFIX):
                    # Update app state
                    app_key = key.removeprefix(State.APP_PREFIX)
                    await self.app_states.update_one(
                        {"app_name": session.app_name, "key": app_key},
                        {"$set": {"value": value}},
                        upsert=True,
                    )

                elif key.startswith(State.USER_PREFIX):
                    # Update user state
                    user_key = key.removeprefix(State.USER_PREFIX)
                    await self.user_states.update_one(
                        {
                            "app_name": session.app_name,
                            "user_id": session.user_id,
                            "key": user_key,
                        },
                        {"$set": {"value": value}},
                        upsert=True,
                    )

        return new_event

use

 session_service = MongoSessionService(mongo_url=config.mongo_db_url, db_name=config.mongo_db_name)
    runner = Runner(
        app_name="opencat",
        agent=root_agent,
        session_service=session_service,
        auto_create_session=True,
    )

@Vasanthan88 This is a temporary solution in my project

@JesserHamdaoui

Hi! I just came across this issue and wanted to check in. Is there still interest in getting an official MongoDBSessionService into the codebase? @JesserHamdaoui mentioned being willing to contribute, has there been any movement on that? I'm also interested in helping out.

@atandon2024

Hi @atandon2024
Go ahead! I'd be happy to review and help if needed.

🚨 Automated Spam Detection Alert 🚨
@maintainers, a suspected spam comment was detected in this thread.

Reason:

@impeachmentright posted promotional spam offering services as a 'Live A2A contractor' with a link to an external website (https://a2a.elonsusk.com/).

Thanks everyone for the interest and discussion here! Quick update: we currently have an official MongoDB session integration ongoing and support for it will be landing soon. Stay tuned!

@Vasanthan88

hi @Vasanthan88, thanks for asking for this, and thanks to everyone who weighed in on the thread. mongodb session storage landed in 9833835 (#7511, with thanks to @theshanbhag for building it) and shipped in 2.13.0. you can install it with pip install 'google-adk[mongodb]' and use MongoDbSessionService from google.adk.integrations.mongodb to store sessions, events, and app, user, and session state in mongodb. it's experimental for now, and there's a runner example in docs/guides/integrations/mongodb/session_service to get you started. if anything's missing for your setup, please open a new issue so we can take a look.

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Need session storage for NoSQL DB #4834

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Need session storage for NoSQL DB #4834

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klateefa commented on Mar 16, 2026

Vasanthan88 commented on Mar 16, 2026

JesserHamdaoui commented on Mar 17, 2026

InfernalAzazel commented on Mar 23, 2026

InfernalAzazel commented on Mar 23, 2026

atandon2024 commented on Jun 28, 2026

JesserHamdaoui commented on Jul 1, 2026

adk-bot commented on Jul 21, 2026

DeanChensj commented on Oct 14, 2026

GWeale commented on Oct 26, 2026

github-actions commented on Oct 26, 2026

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