[Bug]: db_name should return when list_connections called

[hasansustcse13]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I have a requirement where I need to connect to different db on same address (host + port) at the same time. And I have to use existing connection if it's alive for this is the code has been written (basically written in langchain codebase)

  if given_address is not None:
            for con in connections.list_connections():
                addr = connections.get_connection_addr(con[0])
                if (
                    con[1]
                    and ("address" in addr)
                    and (addr["address"] == given_address)
                    and ("user" in addr)
                    and (addr["user"] == tmp_user)
                ):
                    logger.debug("Using previous connection: %s", con[0])
                    return con[0]

        # Generate a new connection if one doesn't exist
        alias = uuid4().hex
        try:
            connections.connect(alias=alias, **connection_args)
            logger.debug("Created new connection using: %s", alias)
            return alias
        except MilvusException as e:
            logger.error("Failed to create new connection using: %s", alias)
            raise e

Let's say collection_1 is connected to db_1 and Now I want collection_2 will be connect to db_2. As addr = connections.get_connection_addr(con[0]) don't have the db_name value the if block will be executed and provide db_1 connection which is wrong.

I believe this is single line fix when connect to milvus we should store the db_name instead of popping.
Code from Milvus:

def connect_milvus(**kwargs):
            # rest of the code
            kwargs.pop("password")
            kwargs.pop("token", None)
            kwargs.pop("db_name", "")  # the bug

            self._connected_alias[alias] = gh
            self._alias[alias] = copy.deepcopy(kwargs)

Expected Behavior

No response

Steps/Code To Reproduce behavior

No response

Environment details

- Hardware/Softward conditions (OS, CPU, GPU, Memory):
- Method of installation (Docker, or from source):
- Milvus version (v0.3.1, or v0.4.0):
- Milvus configuration (Settings you made in `server_config.yaml`):

Anything else?

No response

[tvvignesh]

@XuanYang-cn I am facing the same issue where I am unable to switch different databases for collections in langchain. It all goes to default even when db_name is specified in connection_args in langchain_milvus and debugging further it looks like its a related issue to this.

Also, noticed this PR. Would it resolve this issue? #1446

To get it working, I need to call this on every database I am connected to before running the operation so that the registry is clean and then connect back again. This looks like a bug, not a feature.

This works:

connections.disconnect("default")
connections.remove_connection("default")

connections.disconnect("db1")
connections.remove_connection("db1")

vectorstore = Milvus(
            self.embeddings,
            collection_name=collection_name,
            auto_id=True,
            connection_args={
                "user": self.user,
                "password": self.password,
                "host": self.host,
                "port": self.port,
                "db_name": self.db_name,
            },
            index_params={}
        )

If I directly do it without that, it doesn't since the existing connections array is not empty and you are always picking con[0]

[tvvignesh]

Also, the connection object seems global in nature - can that be made local? For eg. lets say I want to have a dict like this:

{
"db1":con1,
"db2":con2
}

This currently doesn't seem possible since all connections seem to go in a global connections object if I am not wrong

Similar stackoverflow thread here: https://stackoverflow.com/a/78144442

[tvvignesh]

@XuanYang-cn Was able to get it working by modifying pymilvus package - requesting to make appropriate changes in the package as well. Thanks

1st change: I had to add this condition to if in pymilvus to reuse connection by comparing db_name as well (line 346 in screenshot) in langchain_milvus package in connections.py

Also, I got rid of popping db_name from connections.py in pymilvus package

[hasansustcse13]

@XuanYang-cn I believe this was just one line fix. Do you have a plan to fix it? Langchain team has made the changes which now make it worst as if I provide db name anything else rather than default it will create new connection every time.
Langchain Merged: https://github.com/langchain-ai/langchain/pull/25627/files

CC: @tvvignesh