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## Summary The relay no longer runs database aggregate queries to emit usage gauges. Fleet and per-community counts of users, channels, relay members, workflows, git repos, communities, messages, and active users/channels are no longer relay metrics, and neither are the snapshot health gauges that came with them. ### Removed - **Gauges:** `buzz_total_users`, `buzz_total_channels`, `buzz_total_relay_members`, `buzz_total_workflows`, `buzz_total_git_repos`, `buzz_total_active_users`, `buzz_total_messages`, `buzz_total_active_channels`, `buzz_communities_estimated` / `buzz_communities_total`, and every DB-derived `buzz_community_*` series (users, channels, messages, relay members, workflows, git repos, active users, active channels). - **Per-community mode:** `BUZZ_USAGE_METRICS_PER_COMMUNITY=all` and everything it fed: the per-community in-memory gauges, `buzz_community_storage_bytes` / `buzz_community_storage_objects`, `buzz_storage_unmapped_community_bytes`, the community → host map query, and the emission-scope bookkeeping that cleared series for renamed or removed communities. No deployment set it. If one still does, the relay ignores it. - **Health signals:** `buzz_usage_snapshot_available`, `buzz_usage_snapshot_age_seconds`, `buzz_usage_query_skipped_total`, and the `usage_fleet_*` paths of `buzz_db_route_decision`. - **Code and config:** - `buzz-db/src/store/usage.rs`, including its aggregate queries. - The relay's `FleetUsageSchedule` and its cadence/deadline/retry machinery. - The replica-only telemetry route (`Db::route_usage_read`). - `BUZZ_USAGE_METRICS_REPLICA_MAX_AGE_MS` and `DbConfig::usage_metrics_replica_max_age_ms`. If a deployment still sets the env var, the relay now ignores it; startup doesn't fail. - **Reader maintenance pool operation:** `ReaderOperation::Maintenance` and its `close_on_drop` release path existed only for those telemetry reads, so they're removed too. The pool-acquire contract drops from twelve to eleven valid pairs, which lowers the per-pod series ceiling from 216 to 198. - **Dead code:** `Db::active_community_hosts` had no callers. ### Kept - **Leader:** the usage poller's leader lock, plus the leader's invite reaping and fleet storage-snapshot gauges. The session advisory lock (`SessionLeader`, `Db::try_lock_session_leader`) moves to `buzz-db/src/store/leader_lock.rs`, since storage-usage delivery uses it too and it has nothing to do with usage queries. - **In-memory gauges:** pod-local connection, subscription, and online-user gauges. They read process state, not the database. - **Writer maintenance pool operation:** `WriterOperation::Maintenance` stays. Dozens of writer-side maintenance paths across `buzz-db` use it (reapers, retention, the leader lock). The reader variant only ever served the telemetry reads. - **Storage-usage delivery:** unchanged. It reads the storage snapshot for billing, not for metrics. `docs/usage-metrics.md`, `docs/storage-accounting.md`, `.env.example`, and the Helm chart README are updated to match. ## What got simpler This is net deletion (~3.6k lines). One telemetry subsystem is gone: two collection families with independent cadences, availability and age semantics, relay-side deadlines, a dedicated replica routing policy, two config knobs, a per-community emission mode, and a pool-operation variant. Leader election now does only leader work, and it lives in its own module. ## Operational note Dashboards and monitors that read the removed series will go to no data once this rolls out. ## Testing - `cargo fmt --check`, workspace `cargo clippy --all-targets -D warnings`. - `buzz-db` lib, `observability_source`, and doc tests. - `buzz-relay` lib tests. - The Postgres lane for `buzz-db` (lib + tests) and `buzz-relay` (lib). All of these run on a remote workstation at the PR head. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Signed-off-by: Luke Tornquist <tornquist@squareup.com> Co-authored-by: Elrond <28d6302a099e5225b02c4155ac4236e4912603df2ab08dbfc2f4fef08ce598c8@buzz.block.builderlab.xyz> Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
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Usage metrics operations
The relay runs no database aggregate queries for usage telemetry, and it emits no per-community usage series. Its usage poller emits pod-local in-memory gauges and republishes fleet totals from the stored storage snapshot. Fleet counts of users, channels, members, workflows, repositories, and active users are not relay metrics.
In-memory gauges
Every pod exports its own buzz_total_ws_connections,
buzz_total_users_online_pod, and buzz_total_subscriptions. They come from
live process state, so dashboards aggregate them with sum() across pods.
Storage gauges
Storage totals come from the buzz-admin worker snapshot and carry their own
buzz_storage_snapshot_load_ok and buzz_storage_snapshot_age_seconds health
gauges; see storage-accounting.md. Storage gauges are
leader-only: in a multi-pod deployment, first filter them to the pod where
buzz_usage_poller_is_leader == 1; do not take an unfiltered maximum across
pods.
Leader election
Every relay process attempts the same PostgreSQL session advisory lock. Exactly one live database session owns it. The leader reaps expired relay invites and publishes the storage gauges. If that process or session exits, PostgreSQL releases the lock and another relay acquires it.