Top-K leaderboards: four windows, one config

One firehose, four leaderboards. Sliding (10s and 1min), tumbling (per-minute), and lifetime, all declared in a single live.aggregate({ windows }) block. Crank the speed slider; watch sliding twitch while the minute window resets sharply on the boundary and lifetime drifts up.

Firehose (5 events/sec)

0 = pause 50

Bias

12 items, equal weight

Last 10 seconds

sliding window, 1s hops · bars: share of shown

Connecting to firehose...

Last minute

sliding window, 5s hops · bars: share of shown

Connecting to firehose...

This minute

tumbling, resets each min · bars: share of shown

Connecting to firehose...

Lifetime

never resets · bars: share of shown

Connecting to firehose...

Server: one live.aggregate('demos:topk:event', { counts, top }, { topic, windows }) declares all four windows. Each window slice maintains its own state and publishes to a derived topic at ${topic}:${windowName}. The vite plugin generates a namespace export, so trending.last10s.subscribe(...) Just Works on the client.

Sliding windows partition state into hop buckets (10 buckets of 1s for last10s, 12 of 5s for last1min). Each reduce writes into the current bucket; on each slide tick the oldest drops and a new one starts. The combineCounts built-in merges per-bucket states into the full window state at compute time. Tumbling resets at the wall-clock boundary; lifetime never resets.

With speed=0 the firehose stops publishing; sliding decays over its window length while lifetime stays. With "monopoly" bias one item dominates everywhere; with "uniform" the noise spreads so much that leaderboard positions reshuffle constantly on last10s but stay stable on lifetime.