NIP-45 ====== Event Counts ------------ `draft` `optional` Relays may support the verb `COUNT`, which provides a mechanism for obtaining event counts. ## Motivation Some queries a client may want to execute against connected relays are prohibitively expensive, for example, in order to retrieve follower counts for a given pubkey, a client must query all kind-3 events referring to a given pubkey only to count them. The result may be cached, either by a client or by a separate indexing server as an alternative, but both options erode the decentralization of the network by creating a second-layer protocol on top of Nostr. ## Filters and return values This NIP defines the verb `COUNT`, which accepts a subscription id and filters as specified in [NIP 01](01.md) for the verb `REQ`. Multiple filters are OR'd together and aggregated into a single count result. ``` ["COUNT", <subscription_id>, <filters JSON>...] ``` Counts are returned using a `COUNT` response in the form `{"count": <integer>}`. Relays may use probabilistic counts to reduce compute requirements. In case a relay uses probabilistic counts, it MAY indicate it in the response with `approximate` key i.e. `{"count": <integer>, "approximate": <true|false>}`. ``` ["COUNT", <subscription_id>, {"count": <integer>}] ``` Whenever the relay decides to refuse to fulfill the `COUNT` request, it MUST return a `CLOSED` message. ## Examples ### Followers count ``` ["COUNT", <subscription_id>, {"kinds": [3], "#p": [<pubkey>]}] ["COUNT", <subscription_id>, {"count": 238}] ``` ### Count posts and reactions ``` ["COUNT", <subscription_id>, {"kinds": [1, 7], "authors": [<pubkey>]}] ["COUNT", <subscription_id>, {"count": 5}] ``` ### Count posts approximately ``` ["COUNT", <subscription_id>, {"kinds": [1]}] ["COUNT", <subscription_id>, {"count": 93412452, "approximate": true}] ``` ### Relay refuses to count ``` ["COUNT", <subscription_id>, {"kinds": [4], "authors": [<pubkey>], "#p": [<pubkey>]}] ["CLOSED", <subscription_id>, "auth-required: cannot count other people's DMs"] ```