What does checkpoint_ns stands for?

[jiwonmik]

I'm using PostgresSaver and I'm curious what checkpoint_ns stands for?

CREATE TABLE IF NOT EXISTS checkpoints (
    thread_id TEXT NOT NULL,
    checkpoint_ns TEXT NOT NULL DEFAULT '',
    checkpoint_id TEXT NOT NULL,
    parent_checkpoint_id TEXT,
    type TEXT,
    checkpoint JSONB NOT NULL,
    metadata JSONB NOT NULL DEFAULT '{}',
    PRIMARY KEY (thread_id, checkpoint_ns, checkpoint_id)

[vbarda]

@jiwonmik checkpoint_ns stands for checkpoint namespace -- it shows which graph the checkpoint originates from. "" means root graph, otherwise it's a "|"-separated path to a subgraph node. for example, if a parent graph has subgraph in a node called child, the checkpoint_ns value for child checkpoints will be child as well. if a child subgraph has a grandchild subgraph node, checkpoint_ns for grandchild checkpoints will be child|grandchild

[jiwonmik]

Thanks for the explanation 🙏🏻