PostgresSaver.list() unnecessarily requires thread_id

[epistoteles]

TL;DR: Feature request for relaxation of the assumptions of _search_where() in BasePostgresSaver, such that queries like this become possible: "Show me all checkpoints with a given user_id in the metadata".

I have a PostgresSaver that automatically saves threads with the following config:
{"configurable": {"thread_id": thread_id, "user_id": user_id}}

I would like to use the PostgresSaver.list() function to list all threads that belong to a given user_id. I believe I can filter by user_id with a metadata filter, but the underying BasePostgresSaver._search_where() requires a thread_id as a where filter from the configurable:

# construct predicate for config filter
if config:
    wheres.append("thread_id = %s ")
    param_values.append(config["configurable"]["thread_id"])
    checkpoint_ns = config["configurable"].get("checkpoint_ns")
    if checkpoint_ns is not None:
        wheres.append("checkpoint_ns = %s")
        param_values.append(checkpoint_ns)
    if checkpoint_id := get_checkpoint_id(config):
        wheres.append("checkpoint_id = %s ")
        param_values.append(checkpoint_id)

In my view this is not necessary. It should be possible to retrieve checkpoints with an emtpy configurable and only metadata filters, like this:

# construct predicate for config filter
if config:
    thread_id = config["configurable"].get("thread_id")
    if thread_id is not None:
        wheres.append("thread_id = %s ")
        param_values.append(config["configurable"]["thread_id"])
    checkpoint_ns = config["configurable"].get("checkpoint_ns")
    if checkpoint_ns is not None:
        wheres.append("checkpoint_ns = %s")
        param_values.append(checkpoint_ns)
    if checkpoint_id := get_checkpoint_id(config):
        wheres.append("checkpoint_id = %s ")
        param_values.append(checkpoint_id)

Please make me aware of cases in which this change would cause trouble.

[vbarda]

@epistoteles this is a good suggestion, thank you! we'll relax this across checkpointers, stay tuned

[epistoteles]

Happy to submit my own PR if you're fine with that :)

[phdd]

Setting config to none works for me at the moment.

saver.list(
    config=None,
    filter={
        "user_id": user_id
    })